[External] Remove external from RT-Thread

1 files changed, 0 insertions, 6144 deletions

diff --git a/components/external/SQLite-3.8.1/src/where.c b/components/external/SQLite-3.8.1/src/where.c
deleted file mode 100644
index d89ce65137..0000000000
--- a/components/external/SQLite-3.8.1/src/where.c
+++ /dev/null
@@ -1,6144 +0,0 @@
-/*
-** 2001 September 15
-**
-** The author disclaims copyright to this source code.  In place of
-** a legal notice, here is a blessing:
-**
-**    May you do good and not evil.
-**    May you find forgiveness for yourself and forgive others.
-**    May you share freely, never taking more than you give.
-**
-*************************************************************************
-** This module contains C code that generates VDBE code used to process
-** the WHERE clause of SQL statements.  This module is responsible for
-** generating the code that loops through a table looking for applicable
-** rows.  Indices are selected and used to speed the search when doing
-** so is applicable.  Because this module is responsible for selecting
-** indices, you might also think of this module as the "query optimizer".
-*/
-#include "sqliteInt.h"
-
-
-/*
-** Trace output macros
-*/
-#if defined(SQLITE_TEST) || defined(SQLITE_DEBUG)
-/***/ int sqlite3WhereTrace = 0;
-#endif
-#if defined(SQLITE_DEBUG) \
-    && (defined(SQLITE_TEST) || defined(SQLITE_ENABLE_WHERETRACE))
-# define WHERETRACE(K,X)  if(sqlite3WhereTrace&(K)) sqlite3DebugPrintf X
-# define WHERETRACE_ENABLED 1
-#else
-# define WHERETRACE(K,X)
-#endif
-
-/* Forward references
-*/
-typedef struct WhereClause WhereClause;
-typedef struct WhereMaskSet WhereMaskSet;
-typedef struct WhereOrInfo WhereOrInfo;
-typedef struct WhereAndInfo WhereAndInfo;
-typedef struct WhereLevel WhereLevel;
-typedef struct WhereLoop WhereLoop;
-typedef struct WherePath WherePath;
-typedef struct WhereTerm WhereTerm;
-typedef struct WhereLoopBuilder WhereLoopBuilder;
-typedef struct WhereScan WhereScan;
-typedef struct WhereOrCost WhereOrCost;
-typedef struct WhereOrSet WhereOrSet;
-
-/*
-** This object contains information needed to implement a single nested
-** loop in WHERE clause.
-**
-** Contrast this object with WhereLoop.  This object describes the
-** implementation of the loop.  WhereLoop describes the algorithm.
-** This object contains a pointer to the WhereLoop algorithm as one of
-** its elements.
-**
-** The WhereInfo object contains a single instance of this object for
-** each term in the FROM clause (which is to say, for each of the
-** nested loops as implemented).  The order of WhereLevel objects determines
-** the loop nested order, with WhereInfo.a[0] being the outer loop and
-** WhereInfo.a[WhereInfo.nLevel-1] being the inner loop.
-*/
-struct WhereLevel {
-  int iLeftJoin;        /* Memory cell used to implement LEFT OUTER JOIN */
-  int iTabCur;          /* The VDBE cursor used to access the table */
-  int iIdxCur;          /* The VDBE cursor used to access pIdx */
-  int addrBrk;          /* Jump here to break out of the loop */
-  int addrNxt;          /* Jump here to start the next IN combination */
-  int addrCont;         /* Jump here to continue with the next loop cycle */
-  int addrFirst;        /* First instruction of interior of the loop */
-  int addrBody;         /* Beginning of the body of this loop */
-  u8 iFrom;             /* Which entry in the FROM clause */
-  u8 op, p5;            /* Opcode and P5 of the opcode that ends the loop */
-  int p1, p2;           /* Operands of the opcode used to ends the loop */
-  union {               /* Information that depends on pWLoop->wsFlags */
-    struct {
-      int nIn;              /* Number of entries in aInLoop[] */
-      struct InLoop {
-        int iCur;              /* The VDBE cursor used by this IN operator */
-        int addrInTop;         /* Top of the IN loop */
-        u8 eEndLoopOp;         /* IN Loop terminator. OP_Next or OP_Prev */
-      } *aInLoop;           /* Information about each nested IN operator */
-    } in;                 /* Used when pWLoop->wsFlags&WHERE_IN_ABLE */
-    Index *pCovidx;       /* Possible covering index for WHERE_MULTI_OR */
-  } u;
-  struct WhereLoop *pWLoop;  /* The selected WhereLoop object */
-  Bitmask notReady;          /* FROM entries not usable at this level */
-};
-
-/*
-** Each instance of this object represents an algorithm for evaluating one
-** term of a join.  Every term of the FROM clause will have at least
-** one corresponding WhereLoop object (unless INDEXED BY constraints
-** prevent a query solution - which is an error) and many terms of the
-** FROM clause will have multiple WhereLoop objects, each describing a
-** potential way of implementing that FROM-clause term, together with
-** dependencies and cost estimates for using the chosen algorithm.
-**
-** Query planning consists of building up a collection of these WhereLoop
-** objects, then computing a particular sequence of WhereLoop objects, with
-** one WhereLoop object per FROM clause term, that satisfy all dependencies
-** and that minimize the overall cost.
-*/
-struct WhereLoop {
-  Bitmask prereq;       /* Bitmask of other loops that must run first */
-  Bitmask maskSelf;     /* Bitmask identifying table iTab */
-#ifdef SQLITE_DEBUG
-  char cId;             /* Symbolic ID of this loop for debugging use */
-#endif
-  u8 iTab;              /* Position in FROM clause of table for this loop */
-  u8 iSortIdx;          /* Sorting index number.  0==None */
-  LogEst rSetup;        /* One-time setup cost (ex: create transient index) */
-  LogEst rRun;          /* Cost of running each loop */
-  LogEst nOut;          /* Estimated number of output rows */
-  union {
-    struct {               /* Information for internal btree tables */
-      int nEq;               /* Number of equality constraints */
-      Index *pIndex;         /* Index used, or NULL */
-    } btree;
-    struct {               /* Information for virtual tables */
-      int idxNum;            /* Index number */
-      u8 needFree;           /* True if sqlite3_free(idxStr) is needed */
-      u8 isOrdered;          /* True if satisfies ORDER BY */
-      u16 omitMask;          /* Terms that may be omitted */
-      char *idxStr;          /* Index identifier string */
-    } vtab;
-  } u;
-  u32 wsFlags;          /* WHERE_* flags describing the plan */
-  u16 nLTerm;           /* Number of entries in aLTerm[] */
-  /**** whereLoopXfer() copies fields above ***********************/
-# define WHERE_LOOP_XFER_SZ offsetof(WhereLoop,nLSlot)
-  u16 nLSlot;           /* Number of slots allocated for aLTerm[] */
-  WhereTerm **aLTerm;   /* WhereTerms used */
-  WhereLoop *pNextLoop; /* Next WhereLoop object in the WhereClause */
-  WhereTerm *aLTermSpace[4];  /* Initial aLTerm[] space */
-};
-
-/* This object holds the prerequisites and the cost of running a
-** subquery on one operand of an OR operator in the WHERE clause.
-** See WhereOrSet for additional information 
-*/
-struct WhereOrCost {
-  Bitmask prereq;     /* Prerequisites */
-  LogEst rRun;        /* Cost of running this subquery */
-  LogEst nOut;        /* Number of outputs for this subquery */
-};
-
-/* The WhereOrSet object holds a set of possible WhereOrCosts that
-** correspond to the subquery(s) of OR-clause processing.  Only the
-** best N_OR_COST elements are retained.
-*/
-#define N_OR_COST 3
-struct WhereOrSet {
-  u16 n;                      /* Number of valid a[] entries */
-  WhereOrCost a[N_OR_COST];   /* Set of best costs */
-};
-
-
-/* Forward declaration of methods */
-static int whereLoopResize(sqlite3*, WhereLoop*, int);
-
-/*
-** Each instance of this object holds a sequence of WhereLoop objects
-** that implement some or all of a query plan.
-**
-** Think of each WhereLoop object as a node in a graph with arcs
-** showing dependencies and costs for travelling between nodes.  (That is
-** not a completely accurate description because WhereLoop costs are a
-** vector, not a scalar, and because dependencies are many-to-one, not
-** one-to-one as are graph nodes.  But it is a useful visualization aid.)
-** Then a WherePath object is a path through the graph that visits some
-** or all of the WhereLoop objects once.
-**
-** The "solver" works by creating the N best WherePath objects of length
-** 1.  Then using those as a basis to compute the N best WherePath objects
-** of length 2.  And so forth until the length of WherePaths equals the
-** number of nodes in the FROM clause.  The best (lowest cost) WherePath
-** at the end is the choosen query plan.
-*/
-struct WherePath {
-  Bitmask maskLoop;     /* Bitmask of all WhereLoop objects in this path */
-  Bitmask revLoop;      /* aLoop[]s that should be reversed for ORDER BY */
-  LogEst nRow;          /* Estimated number of rows generated by this path */
-  LogEst rCost;         /* Total cost of this path */
-  u8 isOrdered;         /* True if this path satisfies ORDER BY */
-  u8 isOrderedValid;    /* True if the isOrdered field is valid */
-  WhereLoop **aLoop;    /* Array of WhereLoop objects implementing this path */
-};
-
-/*
-** The query generator uses an array of instances of this structure to
-** help it analyze the subexpressions of the WHERE clause.  Each WHERE
-** clause subexpression is separated from the others by AND operators,
-** usually, or sometimes subexpressions separated by OR.
-**
-** All WhereTerms are collected into a single WhereClause structure.  
-** The following identity holds:
-**
-**        WhereTerm.pWC->a[WhereTerm.idx] == WhereTerm
-**
-** When a term is of the form:
-**
-**              X <op> <expr>
-**
-** where X is a column name and <op> is one of certain operators,
-** then WhereTerm.leftCursor and WhereTerm.u.leftColumn record the
-** cursor number and column number for X.  WhereTerm.eOperator records
-** the <op> using a bitmask encoding defined by WO_xxx below.  The
-** use of a bitmask encoding for the operator allows us to search
-** quickly for terms that match any of several different operators.
-**
-** A WhereTerm might also be two or more subterms connected by OR:
-**
-**         (t1.X <op> <expr>) OR (t1.Y <op> <expr>) OR ....
-**
-** In this second case, wtFlag has the TERM_ORINFO bit set and eOperator==WO_OR
-** and the WhereTerm.u.pOrInfo field points to auxiliary information that
-** is collected about the OR clause.
-**
-** If a term in the WHERE clause does not match either of the two previous
-** categories, then eOperator==0.  The WhereTerm.pExpr field is still set
-** to the original subexpression content and wtFlags is set up appropriately
-** but no other fields in the WhereTerm object are meaningful.
-**
-** When eOperator!=0, prereqRight and prereqAll record sets of cursor numbers,
-** but they do so indirectly.  A single WhereMaskSet structure translates
-** cursor number into bits and the translated bit is stored in the prereq
-** fields.  The translation is used in order to maximize the number of
-** bits that will fit in a Bitmask.  The VDBE cursor numbers might be
-** spread out over the non-negative integers.  For example, the cursor
-** numbers might be 3, 8, 9, 10, 20, 23, 41, and 45.  The WhereMaskSet
-** translates these sparse cursor numbers into consecutive integers
-** beginning with 0 in order to make the best possible use of the available
-** bits in the Bitmask.  So, in the example above, the cursor numbers
-** would be mapped into integers 0 through 7.
-**
-** The number of terms in a join is limited by the number of bits
-** in prereqRight and prereqAll.  The default is 64 bits, hence SQLite
-** is only able to process joins with 64 or fewer tables.
-*/
-struct WhereTerm {
-  Expr *pExpr;            /* Pointer to the subexpression that is this term */
-  int iParent;            /* Disable pWC->a[iParent] when this term disabled */
-  int leftCursor;         /* Cursor number of X in "X <op> <expr>" */
-  union {
-    int leftColumn;         /* Column number of X in "X <op> <expr>" */
-    WhereOrInfo *pOrInfo;   /* Extra information if (eOperator & WO_OR)!=0 */
-    WhereAndInfo *pAndInfo; /* Extra information if (eOperator& WO_AND)!=0 */
-  } u;
-  LogEst truthProb;       /* Probability of truth for this expression */
-  u16 eOperator;          /* A WO_xx value describing <op> */
-  u8 wtFlags;             /* TERM_xxx bit flags.  See below */
-  u8 nChild;              /* Number of children that must disable us */
-  WhereClause *pWC;       /* The clause this term is part of */
-  Bitmask prereqRight;    /* Bitmask of tables used by pExpr->pRight */
-  Bitmask prereqAll;      /* Bitmask of tables referenced by pExpr */
-};
-
-/*
-** Allowed values of WhereTerm.wtFlags
-*/
-#define TERM_DYNAMIC    0x01   /* Need to call sqlite3ExprDelete(db, pExpr) */
-#define TERM_VIRTUAL    0x02   /* Added by the optimizer.  Do not code */
-#define TERM_CODED      0x04   /* This term is already coded */
-#define TERM_COPIED     0x08   /* Has a child */
-#define TERM_ORINFO     0x10   /* Need to free the WhereTerm.u.pOrInfo object */
-#define TERM_ANDINFO    0x20   /* Need to free the WhereTerm.u.pAndInfo obj */
-#define TERM_OR_OK      0x40   /* Used during OR-clause processing */
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-#  define TERM_VNULL    0x80   /* Manufactured x>NULL or x<=NULL term */
-#else
-#  define TERM_VNULL    0x00   /* Disabled if not using stat3 */
-#endif
-
-/*
-** An instance of the WhereScan object is used as an iterator for locating
-** terms in the WHERE clause that are useful to the query planner.
-*/
-struct WhereScan {
-  WhereClause *pOrigWC;      /* Original, innermost WhereClause */
-  WhereClause *pWC;          /* WhereClause currently being scanned */
-  char *zCollName;           /* Required collating sequence, if not NULL */
-  char idxaff;               /* Must match this affinity, if zCollName!=NULL */
-  unsigned char nEquiv;      /* Number of entries in aEquiv[] */
-  unsigned char iEquiv;      /* Next unused slot in aEquiv[] */
-  u32 opMask;                /* Acceptable operators */
-  int k;                     /* Resume scanning at this->pWC->a[this->k] */
-  int aEquiv[22];            /* Cursor,Column pairs for equivalence classes */
-};
-
-/*
-** An instance of the following structure holds all information about a
-** WHERE clause.  Mostly this is a container for one or more WhereTerms.
-**
-** Explanation of pOuter:  For a WHERE clause of the form
-**
-**           a AND ((b AND c) OR (d AND e)) AND f
-**
-** There are separate WhereClause objects for the whole clause and for
-** the subclauses "(b AND c)" and "(d AND e)".  The pOuter field of the
-** subclauses points to the WhereClause object for the whole clause.
-*/
-struct WhereClause {
-  WhereInfo *pWInfo;       /* WHERE clause processing context */
-  WhereClause *pOuter;     /* Outer conjunction */
-  u8 op;                   /* Split operator.  TK_AND or TK_OR */
-  int nTerm;               /* Number of terms */
-  int nSlot;               /* Number of entries in a[] */
-  WhereTerm *a;            /* Each a[] describes a term of the WHERE cluase */
-#if defined(SQLITE_SMALL_STACK)
-  WhereTerm aStatic[1];    /* Initial static space for a[] */
-#else
-  WhereTerm aStatic[8];    /* Initial static space for a[] */
-#endif
-};
-
-/*
-** A WhereTerm with eOperator==WO_OR has its u.pOrInfo pointer set to
-** a dynamically allocated instance of the following structure.
-*/
-struct WhereOrInfo {
-  WhereClause wc;          /* Decomposition into subterms */
-  Bitmask indexable;       /* Bitmask of all indexable tables in the clause */
-};
-
-/*
-** A WhereTerm with eOperator==WO_AND has its u.pAndInfo pointer set to
-** a dynamically allocated instance of the following structure.
-*/
-struct WhereAndInfo {
-  WhereClause wc;          /* The subexpression broken out */
-};
-
-/*
-** An instance of the following structure keeps track of a mapping
-** between VDBE cursor numbers and bits of the bitmasks in WhereTerm.
-**
-** The VDBE cursor numbers are small integers contained in 
-** SrcList_item.iCursor and Expr.iTable fields.  For any given WHERE 
-** clause, the cursor numbers might not begin with 0 and they might
-** contain gaps in the numbering sequence.  But we want to make maximum
-** use of the bits in our bitmasks.  This structure provides a mapping
-** from the sparse cursor numbers into consecutive integers beginning
-** with 0.
-**
-** If WhereMaskSet.ix[A]==B it means that The A-th bit of a Bitmask
-** corresponds VDBE cursor number B.  The A-th bit of a bitmask is 1<<A.
-**
-** For example, if the WHERE clause expression used these VDBE
-** cursors:  4, 5, 8, 29, 57, 73.  Then the  WhereMaskSet structure
-** would map those cursor numbers into bits 0 through 5.
-**
-** Note that the mapping is not necessarily ordered.  In the example
-** above, the mapping might go like this:  4->3, 5->1, 8->2, 29->0,
-** 57->5, 73->4.  Or one of 719 other combinations might be used. It
-** does not really matter.  What is important is that sparse cursor
-** numbers all get mapped into bit numbers that begin with 0 and contain
-** no gaps.
-*/
-struct WhereMaskSet {
-  int n;                        /* Number of assigned cursor values */
-  int ix[BMS];                  /* Cursor assigned to each bit */
-};
-
-/*
-** This object is a convenience wrapper holding all information needed
-** to construct WhereLoop objects for a particular query.
-*/
-struct WhereLoopBuilder {
-  WhereInfo *pWInfo;        /* Information about this WHERE */
-  WhereClause *pWC;         /* WHERE clause terms */
-  ExprList *pOrderBy;       /* ORDER BY clause */
-  WhereLoop *pNew;          /* Template WhereLoop */
-  WhereOrSet *pOrSet;       /* Record best loops here, if not NULL */
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-  UnpackedRecord *pRec;     /* Probe for stat4 (if required) */
-  int nRecValid;            /* Number of valid fields currently in pRec */
-#endif
-};
-
-/*
-** The WHERE clause processing routine has two halves.  The
-** first part does the start of the WHERE loop and the second
-** half does the tail of the WHERE loop.  An instance of
-** this structure is returned by the first half and passed
-** into the second half to give some continuity.
-**
-** An instance of this object holds the complete state of the query
-** planner.
-*/
-struct WhereInfo {
-  Parse *pParse;            /* Parsing and code generating context */
-  SrcList *pTabList;        /* List of tables in the join */
-  ExprList *pOrderBy;       /* The ORDER BY clause or NULL */
-  ExprList *pResultSet;     /* Result set. DISTINCT operates on these */
-  WhereLoop *pLoops;        /* List of all WhereLoop objects */
-  Bitmask revMask;          /* Mask of ORDER BY terms that need reversing */
-  LogEst nRowOut;           /* Estimated number of output rows */
-  u16 wctrlFlags;           /* Flags originally passed to sqlite3WhereBegin() */
-  u8 bOBSat;                /* ORDER BY satisfied by indices */
-  u8 okOnePass;             /* Ok to use one-pass algorithm for UPDATE/DELETE */
-  u8 untestedTerms;         /* Not all WHERE terms resolved by outer loop */
-  u8 eDistinct;             /* One of the WHERE_DISTINCT_* values below */
-  u8 nLevel;                /* Number of nested loop */
-  int iTop;                 /* The very beginning of the WHERE loop */
-  int iContinue;            /* Jump here to continue with next record */
-  int iBreak;               /* Jump here to break out of the loop */
-  int savedNQueryLoop;      /* pParse->nQueryLoop outside the WHERE loop */
-  WhereMaskSet sMaskSet;    /* Map cursor numbers to bitmasks */
-  WhereClause sWC;          /* Decomposition of the WHERE clause */
-  WhereLevel a[1];          /* Information about each nest loop in WHERE */
-};
-
-/*
-** Bitmasks for the operators on WhereTerm objects.  These are all
-** operators that are of interest to the query planner.  An
-** OR-ed combination of these values can be used when searching for
-** particular WhereTerms within a WhereClause.
-*/
-#define WO_IN     0x001
-#define WO_EQ     0x002
-#define WO_LT     (WO_EQ<<(TK_LT-TK_EQ))
-#define WO_LE     (WO_EQ<<(TK_LE-TK_EQ))
-#define WO_GT     (WO_EQ<<(TK_GT-TK_EQ))
-#define WO_GE     (WO_EQ<<(TK_GE-TK_EQ))
-#define WO_MATCH  0x040
-#define WO_ISNULL 0x080
-#define WO_OR     0x100       /* Two or more OR-connected terms */
-#define WO_AND    0x200       /* Two or more AND-connected terms */
-#define WO_EQUIV  0x400       /* Of the form A==B, both columns */
-#define WO_NOOP   0x800       /* This term does not restrict search space */
-
-#define WO_ALL    0xfff       /* Mask of all possible WO_* values */
-#define WO_SINGLE 0x0ff       /* Mask of all non-compound WO_* values */
-
-/*
-** These are definitions of bits in the WhereLoop.wsFlags field.
-** The particular combination of bits in each WhereLoop help to
-** determine the algorithm that WhereLoop represents.
-*/
-#define WHERE_COLUMN_EQ    0x00000001  /* x=EXPR */
-#define WHERE_COLUMN_RANGE 0x00000002  /* x<EXPR and/or x>EXPR */
-#define WHERE_COLUMN_IN    0x00000004  /* x IN (...) */
-#define WHERE_COLUMN_NULL  0x00000008  /* x IS NULL */
-#define WHERE_CONSTRAINT   0x0000000f  /* Any of the WHERE_COLUMN_xxx values */
-#define WHERE_TOP_LIMIT    0x00000010  /* x<EXPR or x<=EXPR constraint */
-#define WHERE_BTM_LIMIT    0x00000020  /* x>EXPR or x>=EXPR constraint */
-#define WHERE_BOTH_LIMIT   0x00000030  /* Both x>EXPR and x<EXPR */
-#define WHERE_IDX_ONLY     0x00000040  /* Use index only - omit table */
-#define WHERE_IPK          0x00000100  /* x is the INTEGER PRIMARY KEY */
-#define WHERE_INDEXED      0x00000200  /* WhereLoop.u.btree.pIndex is valid */
-#define WHERE_VIRTUALTABLE 0x00000400  /* WhereLoop.u.vtab is valid */
-#define WHERE_IN_ABLE      0x00000800  /* Able to support an IN operator */
-#define WHERE_ONEROW       0x00001000  /* Selects no more than one row */
-#define WHERE_MULTI_OR     0x00002000  /* OR using multiple indices */
-#define WHERE_AUTO_INDEX   0x00004000  /* Uses an ephemeral index */
-
-/*
-** Return the estimated number of output rows from a WHERE clause
-*/
-u64 sqlite3WhereOutputRowCount(WhereInfo *pWInfo){
-  return sqlite3LogEstToInt(pWInfo->nRowOut);
-}
-
-/*
-** Return one of the WHERE_DISTINCT_xxxxx values to indicate how this
-** WHERE clause returns outputs for DISTINCT processing.
-*/
-int sqlite3WhereIsDistinct(WhereInfo *pWInfo){
-  return pWInfo->eDistinct;
-}
-
-/*
-** Return TRUE if the WHERE clause returns rows in ORDER BY order.
-** Return FALSE if the output needs to be sorted.
-*/
-int sqlite3WhereIsOrdered(WhereInfo *pWInfo){
-  return pWInfo->bOBSat!=0;
-}
-
-/*
-** Return the VDBE address or label to jump to in order to continue
-** immediately with the next row of a WHERE clause.
-*/
-int sqlite3WhereContinueLabel(WhereInfo *pWInfo){
-  return pWInfo->iContinue;
-}
-
-/*
-** Return the VDBE address or label to jump to in order to break
-** out of a WHERE loop.
-*/
-int sqlite3WhereBreakLabel(WhereInfo *pWInfo){
-  return pWInfo->iBreak;
-}
-
-/*
-** Return TRUE if an UPDATE or DELETE statement can operate directly on
-** the rowids returned by a WHERE clause.  Return FALSE if doing an
-** UPDATE or DELETE might change subsequent WHERE clause results.
-*/
-int sqlite3WhereOkOnePass(WhereInfo *pWInfo){
-  return pWInfo->okOnePass;
-}
-
-/*
-** Move the content of pSrc into pDest
-*/
-static void whereOrMove(WhereOrSet *pDest, WhereOrSet *pSrc){
-  pDest->n = pSrc->n;
-  memcpy(pDest->a, pSrc->a, pDest->n*sizeof(pDest->a[0]));
-}
-
-/*
-** Try to insert a new prerequisite/cost entry into the WhereOrSet pSet.
-**
-** The new entry might overwrite an existing entry, or it might be
-** appended, or it might be discarded.  Do whatever is the right thing
-** so that pSet keeps the N_OR_COST best entries seen so far.
-*/
-static int whereOrInsert(
-  WhereOrSet *pSet,      /* The WhereOrSet to be updated */
-  Bitmask prereq,        /* Prerequisites of the new entry */
-  LogEst rRun,           /* Run-cost of the new entry */
-  LogEst nOut            /* Number of outputs for the new entry */
-){
-  u16 i;
-  WhereOrCost *p;
-  for(i=pSet->n, p=pSet->a; i>0; i--, p++){
-    if( rRun<=p->rRun && (prereq & p->prereq)==prereq ){
-      goto whereOrInsert_done;
-    }
-    if( p->rRun<=rRun && (p->prereq & prereq)==p->prereq ){
-      return 0;
-    }
-  }
-  if( pSet->n<N_OR_COST ){
-    p = &pSet->a[pSet->n++];
-    p->nOut = nOut;
-  }else{
-    p = pSet->a;
-    for(i=1; i<pSet->n; i++){
-      if( p->rRun>pSet->a[i].rRun ) p = pSet->a + i;
-    }
-    if( p->rRun<=rRun ) return 0;
-  }
-whereOrInsert_done:
-  p->prereq = prereq;
-  p->rRun = rRun;
-  if( p->nOut>nOut ) p->nOut = nOut;
-  return 1;
-}
-
-/*
-** Initialize a preallocated WhereClause structure.
-*/
-static void whereClauseInit(
-  WhereClause *pWC,        /* The WhereClause to be initialized */
-  WhereInfo *pWInfo        /* The WHERE processing context */
-){
-  pWC->pWInfo = pWInfo;
-  pWC->pOuter = 0;
-  pWC->nTerm = 0;
-  pWC->nSlot = ArraySize(pWC->aStatic);
-  pWC->a = pWC->aStatic;
-}
-
-/* Forward reference */
-static void whereClauseClear(WhereClause*);
-
-/*
-** Deallocate all memory associated with a WhereOrInfo object.
-*/
-static void whereOrInfoDelete(sqlite3 *db, WhereOrInfo *p){
-  whereClauseClear(&p->wc);
-  sqlite3DbFree(db, p);
-}
-
-/*
-** Deallocate all memory associated with a WhereAndInfo object.
-*/
-static void whereAndInfoDelete(sqlite3 *db, WhereAndInfo *p){
-  whereClauseClear(&p->wc);
-  sqlite3DbFree(db, p);
-}
-
-/*
-** Deallocate a WhereClause structure.  The WhereClause structure
-** itself is not freed.  This routine is the inverse of whereClauseInit().
-*/
-static void whereClauseClear(WhereClause *pWC){
-  int i;
-  WhereTerm *a;
-  sqlite3 *db = pWC->pWInfo->pParse->db;
-  for(i=pWC->nTerm-1, a=pWC->a; i>=0; i--, a++){
-    if( a->wtFlags & TERM_DYNAMIC ){
-      sqlite3ExprDelete(db, a->pExpr);
-    }
-    if( a->wtFlags & TERM_ORINFO ){
-      whereOrInfoDelete(db, a->u.pOrInfo);
-    }else if( a->wtFlags & TERM_ANDINFO ){
-      whereAndInfoDelete(db, a->u.pAndInfo);
-    }
-  }
-  if( pWC->a!=pWC->aStatic ){
-    sqlite3DbFree(db, pWC->a);
-  }
-}
-
-/*
-** Add a single new WhereTerm entry to the WhereClause object pWC.
-** The new WhereTerm object is constructed from Expr p and with wtFlags.
-** The index in pWC->a[] of the new WhereTerm is returned on success.
-** 0 is returned if the new WhereTerm could not be added due to a memory
-** allocation error.  The memory allocation failure will be recorded in
-** the db->mallocFailed flag so that higher-level functions can detect it.
-**
-** This routine will increase the size of the pWC->a[] array as necessary.
-**
-** If the wtFlags argument includes TERM_DYNAMIC, then responsibility
-** for freeing the expression p is assumed by the WhereClause object pWC.
-** This is true even if this routine fails to allocate a new WhereTerm.
-**
-** WARNING:  This routine might reallocate the space used to store
-** WhereTerms.  All pointers to WhereTerms should be invalidated after
-** calling this routine.  Such pointers may be reinitialized by referencing
-** the pWC->a[] array.
-*/
-static int whereClauseInsert(WhereClause *pWC, Expr *p, u8 wtFlags){
-  WhereTerm *pTerm;
-  int idx;
-  testcase( wtFlags & TERM_VIRTUAL );
-  if( pWC->nTerm>=pWC->nSlot ){
-    WhereTerm *pOld = pWC->a;
-    sqlite3 *db = pWC->pWInfo->pParse->db;
-    pWC->a = sqlite3DbMallocRaw(db, sizeof(pWC->a[0])*pWC->nSlot*2 );
-    if( pWC->a==0 ){
-      if( wtFlags & TERM_DYNAMIC ){
-        sqlite3ExprDelete(db, p);
-      }
-      pWC->a = pOld;
-      return 0;
-    }
-    memcpy(pWC->a, pOld, sizeof(pWC->a[0])*pWC->nTerm);
-    if( pOld!=pWC->aStatic ){
-      sqlite3DbFree(db, pOld);
-    }
-    pWC->nSlot = sqlite3DbMallocSize(db, pWC->a)/sizeof(pWC->a[0]);
-  }
-  pTerm = &pWC->a[idx = pWC->nTerm++];
-  if( p && ExprHasProperty(p, EP_Unlikely) ){
-    pTerm->truthProb = sqlite3LogEst(p->iTable) - 99;
-  }else{
-    pTerm->truthProb = -1;
-  }
-  pTerm->pExpr = sqlite3ExprSkipCollate(p);
-  pTerm->wtFlags = wtFlags;
-  pTerm->pWC = pWC;
-  pTerm->iParent = -1;
-  return idx;
-}
-
-/*
-** This routine identifies subexpressions in the WHERE clause where
-** each subexpression is separated by the AND operator or some other
-** operator specified in the op parameter.  The WhereClause structure
-** is filled with pointers to subexpressions.  For example:
-**
-**    WHERE  a=='hello' AND coalesce(b,11)<10 AND (c+12!=d OR c==22)
-**           \________/     \_______________/     \________________/
-**            slot[0]            slot[1]               slot[2]
-**
-** The original WHERE clause in pExpr is unaltered.  All this routine
-** does is make slot[] entries point to substructure within pExpr.
-**
-** In the previous sentence and in the diagram, "slot[]" refers to
-** the WhereClause.a[] array.  The slot[] array grows as needed to contain
-** all terms of the WHERE clause.
-*/
-static void whereSplit(WhereClause *pWC, Expr *pExpr, u8 op){
-  pWC->op = op;
-  if( pExpr==0 ) return;
-  if( pExpr->op!=op ){
-    whereClauseInsert(pWC, pExpr, 0);
-  }else{
-    whereSplit(pWC, pExpr->pLeft, op);
-    whereSplit(pWC, pExpr->pRight, op);
-  }
-}
-
-/*
-** Initialize a WhereMaskSet object
-*/
-#define initMaskSet(P)  (P)->n=0
-
-/*
-** Return the bitmask for the given cursor number.  Return 0 if
-** iCursor is not in the set.
-*/
-static Bitmask getMask(WhereMaskSet *pMaskSet, int iCursor){
-  int i;
-  assert( pMaskSet->n<=(int)sizeof(Bitmask)*8 );
-  for(i=0; i<pMaskSet->n; i++){
-    if( pMaskSet->ix[i]==iCursor ){
-      return MASKBIT(i);
-    }
-  }
-  return 0;
-}
-
-/*
-** Create a new mask for cursor iCursor.
-**
-** There is one cursor per table in the FROM clause.  The number of
-** tables in the FROM clause is limited by a test early in the
-** sqlite3WhereBegin() routine.  So we know that the pMaskSet->ix[]
-** array will never overflow.
-*/
-static void createMask(WhereMaskSet *pMaskSet, int iCursor){
-  assert( pMaskSet->n < ArraySize(pMaskSet->ix) );
-  pMaskSet->ix[pMaskSet->n++] = iCursor;
-}
-
-/*
-** These routines walk (recursively) an expression tree and generate
-** a bitmask indicating which tables are used in that expression
-** tree.
-*/
-static Bitmask exprListTableUsage(WhereMaskSet*, ExprList*);
-static Bitmask exprSelectTableUsage(WhereMaskSet*, Select*);
-static Bitmask exprTableUsage(WhereMaskSet *pMaskSet, Expr *p){
-  Bitmask mask = 0;
-  if( p==0 ) return 0;
-  if( p->op==TK_COLUMN ){
-    mask = getMask(pMaskSet, p->iTable);
-    return mask;
-  }
-  mask = exprTableUsage(pMaskSet, p->pRight);
-  mask |= exprTableUsage(pMaskSet, p->pLeft);
-  if( ExprHasProperty(p, EP_xIsSelect) ){
-    mask |= exprSelectTableUsage(pMaskSet, p->x.pSelect);
-  }else{
-    mask |= exprListTableUsage(pMaskSet, p->x.pList);
-  }
-  return mask;
-}
-static Bitmask exprListTableUsage(WhereMaskSet *pMaskSet, ExprList *pList){
-  int i;
-  Bitmask mask = 0;
-  if( pList ){
-    for(i=0; i<pList->nExpr; i++){
-      mask |= exprTableUsage(pMaskSet, pList->a[i].pExpr);
-    }
-  }
-  return mask;
-}
-static Bitmask exprSelectTableUsage(WhereMaskSet *pMaskSet, Select *pS){
-  Bitmask mask = 0;
-  while( pS ){
-    SrcList *pSrc = pS->pSrc;
-    mask |= exprListTableUsage(pMaskSet, pS->pEList);
-    mask |= exprListTableUsage(pMaskSet, pS->pGroupBy);
-    mask |= exprListTableUsage(pMaskSet, pS->pOrderBy);
-    mask |= exprTableUsage(pMaskSet, pS->pWhere);
-    mask |= exprTableUsage(pMaskSet, pS->pHaving);
-    if( ALWAYS(pSrc!=0) ){
-      int i;
-      for(i=0; i<pSrc->nSrc; i++){
-        mask |= exprSelectTableUsage(pMaskSet, pSrc->a[i].pSelect);
-        mask |= exprTableUsage(pMaskSet, pSrc->a[i].pOn);
-      }
-    }
-    pS = pS->pPrior;
-  }
-  return mask;
-}
-
-/*
-** Return TRUE if the given operator is one of the operators that is
-** allowed for an indexable WHERE clause term.  The allowed operators are
-** "=", "<", ">", "<=", ">=", "IN", and "IS NULL"
-*/
-static int allowedOp(int op){
-  assert( TK_GT>TK_EQ && TK_GT<TK_GE );
-  assert( TK_LT>TK_EQ && TK_LT<TK_GE );
-  assert( TK_LE>TK_EQ && TK_LE<TK_GE );
-  assert( TK_GE==TK_EQ+4 );
-  return op==TK_IN || (op>=TK_EQ && op<=TK_GE) || op==TK_ISNULL;
-}
-
-/*
-** Swap two objects of type TYPE.
-*/
-#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
-
-/*
-** Commute a comparison operator.  Expressions of the form "X op Y"
-** are converted into "Y op X".
-**
-** If left/right precedence rules come into play when determining the
-** collating sequence, then COLLATE operators are adjusted to ensure
-** that the collating sequence does not change.  For example:
-** "Y collate NOCASE op X" becomes "X op Y" because any collation sequence on
-** the left hand side of a comparison overrides any collation sequence 
-** attached to the right. For the same reason the EP_Collate flag
-** is not commuted.
-*/
-static void exprCommute(Parse *pParse, Expr *pExpr){
-  u16 expRight = (pExpr->pRight->flags & EP_Collate);
-  u16 expLeft = (pExpr->pLeft->flags & EP_Collate);
-  assert( allowedOp(pExpr->op) && pExpr->op!=TK_IN );
-  if( expRight==expLeft ){
-    /* Either X and Y both have COLLATE operator or neither do */
-    if( expRight ){
-      /* Both X and Y have COLLATE operators.  Make sure X is always
-      ** used by clearing the EP_Collate flag from Y. */
-      pExpr->pRight->flags &= ~EP_Collate;
-    }else if( sqlite3ExprCollSeq(pParse, pExpr->pLeft)!=0 ){
-      /* Neither X nor Y have COLLATE operators, but X has a non-default
-      ** collating sequence.  So add the EP_Collate marker on X to cause
-      ** it to be searched first. */
-      pExpr->pLeft->flags |= EP_Collate;
-    }
-  }
-  SWAP(Expr*,pExpr->pRight,pExpr->pLeft);
-  if( pExpr->op>=TK_GT ){
-    assert( TK_LT==TK_GT+2 );
-    assert( TK_GE==TK_LE+2 );
-    assert( TK_GT>TK_EQ );
-    assert( TK_GT<TK_LE );
-    assert( pExpr->op>=TK_GT && pExpr->op<=TK_GE );
-    pExpr->op = ((pExpr->op-TK_GT)^2)+TK_GT;
-  }
-}
-
-/*
-** Translate from TK_xx operator to WO_xx bitmask.
-*/
-static u16 operatorMask(int op){
-  u16 c;
-  assert( allowedOp(op) );
-  if( op==TK_IN ){
-    c = WO_IN;
-  }else if( op==TK_ISNULL ){
-    c = WO_ISNULL;
-  }else{
-    assert( (WO_EQ<<(op-TK_EQ)) < 0x7fff );
-    c = (u16)(WO_EQ<<(op-TK_EQ));
-  }
-  assert( op!=TK_ISNULL || c==WO_ISNULL );
-  assert( op!=TK_IN || c==WO_IN );
-  assert( op!=TK_EQ || c==WO_EQ );
-  assert( op!=TK_LT || c==WO_LT );
-  assert( op!=TK_LE || c==WO_LE );
-  assert( op!=TK_GT || c==WO_GT );
-  assert( op!=TK_GE || c==WO_GE );
-  return c;
-}
-
-/*
-** Advance to the next WhereTerm that matches according to the criteria
-** established when the pScan object was initialized by whereScanInit().
-** Return NULL if there are no more matching WhereTerms.
-*/
-static WhereTerm *whereScanNext(WhereScan *pScan){
-  int iCur;            /* The cursor on the LHS of the term */
-  int iColumn;         /* The column on the LHS of the term.  -1 for IPK */
-  Expr *pX;            /* An expression being tested */
-  WhereClause *pWC;    /* Shorthand for pScan->pWC */
-  WhereTerm *pTerm;    /* The term being tested */
-  int k = pScan->k;    /* Where to start scanning */
-
-  while( pScan->iEquiv<=pScan->nEquiv ){
-    iCur = pScan->aEquiv[pScan->iEquiv-2];
-    iColumn = pScan->aEquiv[pScan->iEquiv-1];
-    while( (pWC = pScan->pWC)!=0 ){
-      for(pTerm=pWC->a+k; k<pWC->nTerm; k++, pTerm++){
-        if( pTerm->leftCursor==iCur && pTerm->u.leftColumn==iColumn ){
-          if( (pTerm->eOperator & WO_EQUIV)!=0
-           && pScan->nEquiv<ArraySize(pScan->aEquiv)
-          ){
-            int j;
-            pX = sqlite3ExprSkipCollate(pTerm->pExpr->pRight);
-            assert( pX->op==TK_COLUMN );
-            for(j=0; j<pScan->nEquiv; j+=2){
-              if( pScan->aEquiv[j]==pX->iTable
-               && pScan->aEquiv[j+1]==pX->iColumn ){
-                  break;
-              }
-            }
-            if( j==pScan->nEquiv ){
-              pScan->aEquiv[j] = pX->iTable;
-              pScan->aEquiv[j+1] = pX->iColumn;
-              pScan->nEquiv += 2;
-            }
-          }
-          if( (pTerm->eOperator & pScan->opMask)!=0 ){
-            /* Verify the affinity and collating sequence match */
-            if( pScan->zCollName && (pTerm->eOperator & WO_ISNULL)==0 ){
-              CollSeq *pColl;
-              Parse *pParse = pWC->pWInfo->pParse;
-              pX = pTerm->pExpr;
-              if( !sqlite3IndexAffinityOk(pX, pScan->idxaff) ){
-                continue;
-              }
-              assert(pX->pLeft);
-              pColl = sqlite3BinaryCompareCollSeq(pParse,
-                                                  pX->pLeft, pX->pRight);
-              if( pColl==0 ) pColl = pParse->db->pDfltColl;
-              if( sqlite3StrICmp(pColl->zName, pScan->zCollName) ){
-                continue;
-              }
-            }
-            if( (pTerm->eOperator & WO_EQ)!=0
-             && (pX = pTerm->pExpr->pRight)->op==TK_COLUMN
-             && pX->iTable==pScan->aEquiv[0]
-             && pX->iColumn==pScan->aEquiv[1]
-            ){
-              continue;
-            }
-            pScan->k = k+1;
-            return pTerm;
-          }
-        }
-      }
-      pScan->pWC = pScan->pWC->pOuter;
-      k = 0;
-    }
-    pScan->pWC = pScan->pOrigWC;
-    k = 0;
-    pScan->iEquiv += 2;
-  }
-  return 0;
-}
-
-/*
-** Initialize a WHERE clause scanner object.  Return a pointer to the
-** first match.  Return NULL if there are no matches.
-**
-** The scanner will be searching the WHERE clause pWC.  It will look
-** for terms of the form "X <op> <expr>" where X is column iColumn of table
-** iCur.  The <op> must be one of the operators described by opMask.
-**
-** If the search is for X and the WHERE clause contains terms of the
-** form X=Y then this routine might also return terms of the form
-** "Y <op> <expr>".  The number of levels of transitivity is limited,
-** but is enough to handle most commonly occurring SQL statements.
-**
-** If X is not the INTEGER PRIMARY KEY then X must be compatible with
-** index pIdx.
-*/
-static WhereTerm *whereScanInit(
-  WhereScan *pScan,       /* The WhereScan object being initialized */
-  WhereClause *pWC,       /* The WHERE clause to be scanned */
-  int iCur,               /* Cursor to scan for */
-  int iColumn,            /* Column to scan for */
-  u32 opMask,             /* Operator(s) to scan for */
-  Index *pIdx             /* Must be compatible with this index */
-){
-  int j;
-
-  /* memset(pScan, 0, sizeof(*pScan)); */
-  pScan->pOrigWC = pWC;
-  pScan->pWC = pWC;
-  if( pIdx && iColumn>=0 ){
-    pScan->idxaff = pIdx->pTable->aCol[iColumn].affinity;
-    for(j=0; pIdx->aiColumn[j]!=iColumn; j++){
-      if( NEVER(j>=pIdx->nColumn) ) return 0;
-    }
-    pScan->zCollName = pIdx->azColl[j];
-  }else{
-    pScan->idxaff = 0;
-    pScan->zCollName = 0;
-  }
-  pScan->opMask = opMask;
-  pScan->k = 0;
-  pScan->aEquiv[0] = iCur;
-  pScan->aEquiv[1] = iColumn;
-  pScan->nEquiv = 2;
-  pScan->iEquiv = 2;
-  return whereScanNext(pScan);
-}
-
-/*
-** Search for a term in the WHERE clause that is of the form "X <op> <expr>"
-** where X is a reference to the iColumn of table iCur and <op> is one of
-** the WO_xx operator codes specified by the op parameter.
-** Return a pointer to the term.  Return 0 if not found.
-**
-** The term returned might by Y=<expr> if there is another constraint in
-** the WHERE clause that specifies that X=Y.  Any such constraints will be
-** identified by the WO_EQUIV bit in the pTerm->eOperator field.  The
-** aEquiv[] array holds X and all its equivalents, with each SQL variable
-** taking up two slots in aEquiv[].  The first slot is for the cursor number
-** and the second is for the column number.  There are 22 slots in aEquiv[]
-** so that means we can look for X plus up to 10 other equivalent values.
-** Hence a search for X will return <expr> if X=A1 and A1=A2 and A2=A3
-** and ... and A9=A10 and A10=<expr>.
-**
-** If there are multiple terms in the WHERE clause of the form "X <op> <expr>"
-** then try for the one with no dependencies on <expr> - in other words where
-** <expr> is a constant expression of some kind.  Only return entries of
-** the form "X <op> Y" where Y is a column in another table if no terms of
-** the form "X <op> <const-expr>" exist.   If no terms with a constant RHS
-** exist, try to return a term that does not use WO_EQUIV.
-*/
-static WhereTerm *findTerm(
-  WhereClause *pWC,     /* The WHERE clause to be searched */
-  int iCur,             /* Cursor number of LHS */
-  int iColumn,          /* Column number of LHS */
-  Bitmask notReady,     /* RHS must not overlap with this mask */
-  u32 op,               /* Mask of WO_xx values describing operator */
-  Index *pIdx           /* Must be compatible with this index, if not NULL */
-){
-  WhereTerm *pResult = 0;
-  WhereTerm *p;
-  WhereScan scan;
-
-  p = whereScanInit(&scan, pWC, iCur, iColumn, op, pIdx);
-  while( p ){
-    if( (p->prereqRight & notReady)==0 ){
-      if( p->prereqRight==0 && (p->eOperator&WO_EQ)!=0 ){
-        return p;
-      }
-      if( pResult==0 ) pResult = p;
-    }
-    p = whereScanNext(&scan);
-  }
-  return pResult;
-}
-
-/* Forward reference */
-static void exprAnalyze(SrcList*, WhereClause*, int);
-
-/*
-** Call exprAnalyze on all terms in a WHERE clause.  
-*/
-static void exprAnalyzeAll(
-  SrcList *pTabList,       /* the FROM clause */
-  WhereClause *pWC         /* the WHERE clause to be analyzed */
-){
-  int i;
-  for(i=pWC->nTerm-1; i>=0; i--){
-    exprAnalyze(pTabList, pWC, i);
-  }
-}
-
-#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
-/*
-** Check to see if the given expression is a LIKE or GLOB operator that
-** can be optimized using inequality constraints.  Return TRUE if it is
-** so and false if not.
-**
-** In order for the operator to be optimizible, the RHS must be a string
-** literal that does not begin with a wildcard.  
-*/
-static int isLikeOrGlob(
-  Parse *pParse,    /* Parsing and code generating context */
-  Expr *pExpr,      /* Test this expression */
-  Expr **ppPrefix,  /* Pointer to TK_STRING expression with pattern prefix */
-  int *pisComplete, /* True if the only wildcard is % in the last character */
-  int *pnoCase      /* True if uppercase is equivalent to lowercase */
-){
-  const char *z = 0;         /* String on RHS of LIKE operator */
-  Expr *pRight, *pLeft;      /* Right and left size of LIKE operator */
-  ExprList *pList;           /* List of operands to the LIKE operator */
-  int c;                     /* One character in z[] */
-  int cnt;                   /* Number of non-wildcard prefix characters */
-  char wc[3];                /* Wildcard characters */
-  sqlite3 *db = pParse->db;  /* Database connection */
-  sqlite3_value *pVal = 0;
-  int op;                    /* Opcode of pRight */
-
-  if( !sqlite3IsLikeFunction(db, pExpr, pnoCase, wc) ){
-    return 0;
-  }
-#ifdef SQLITE_EBCDIC
-  if( *pnoCase ) return 0;
-#endif
-  pList = pExpr->x.pList;
-  pLeft = pList->a[1].pExpr;
-  if( pLeft->op!=TK_COLUMN 
-   || sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT 
-   || IsVirtual(pLeft->pTab)
-  ){
-    /* IMP: R-02065-49465 The left-hand side of the LIKE or GLOB operator must
-    ** be the name of an indexed column with TEXT affinity. */
-    return 0;
-  }
-  assert( pLeft->iColumn!=(-1) ); /* Because IPK never has AFF_TEXT */
-
-  pRight = pList->a[0].pExpr;
-  op = pRight->op;
-  if( op==TK_REGISTER ){
-    op = pRight->op2;
-  }
-  if( op==TK_VARIABLE ){
-    Vdbe *pReprepare = pParse->pReprepare;
-    int iCol = pRight->iColumn;
-    pVal = sqlite3VdbeGetBoundValue(pReprepare, iCol, SQLITE_AFF_NONE);
-    if( pVal && sqlite3_value_type(pVal)==SQLITE_TEXT ){
-      z = (char *)sqlite3_value_text(pVal);
-    }
-    sqlite3VdbeSetVarmask(pParse->pVdbe, iCol);
-    assert( pRight->op==TK_VARIABLE || pRight->op==TK_REGISTER );
-  }else if( op==TK_STRING ){
-    z = pRight->u.zToken;
-  }
-  if( z ){
-    cnt = 0;
-    while( (c=z[cnt])!=0 && c!=wc[0] && c!=wc[1] && c!=wc[2] ){
-      cnt++;
-    }
-    if( cnt!=0 && 255!=(u8)z[cnt-1] ){
-      Expr *pPrefix;
-      *pisComplete = c==wc[0] && z[cnt+1]==0;
-      pPrefix = sqlite3Expr(db, TK_STRING, z);
-      if( pPrefix ) pPrefix->u.zToken[cnt] = 0;
-      *ppPrefix = pPrefix;
-      if( op==TK_VARIABLE ){
-        Vdbe *v = pParse->pVdbe;
-        sqlite3VdbeSetVarmask(v, pRight->iColumn);
-        if( *pisComplete && pRight->u.zToken[1] ){
-          /* If the rhs of the LIKE expression is a variable, and the current
-          ** value of the variable means there is no need to invoke the LIKE
-          ** function, then no OP_Variable will be added to the program.
-          ** This causes problems for the sqlite3_bind_parameter_name()
-          ** API. To workaround them, add a dummy OP_Variable here.
-          */ 
-          int r1 = sqlite3GetTempReg(pParse);
-          sqlite3ExprCodeTarget(pParse, pRight, r1);
-          sqlite3VdbeChangeP3(v, sqlite3VdbeCurrentAddr(v)-1, 0);
-          sqlite3ReleaseTempReg(pParse, r1);
-        }
-      }
-    }else{
-      z = 0;
-    }
-  }
-
-  sqlite3ValueFree(pVal);
-  return (z!=0);
-}
-#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
-
-
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-/*
-** Check to see if the given expression is of the form
-**
-**         column MATCH expr
-**
-** If it is then return TRUE.  If not, return FALSE.
-*/
-static int isMatchOfColumn(
-  Expr *pExpr      /* Test this expression */
-){
-  ExprList *pList;
-
-  if( pExpr->op!=TK_FUNCTION ){
-    return 0;
-  }
-  if( sqlite3StrICmp(pExpr->u.zToken,"match")!=0 ){
-    return 0;
-  }
-  pList = pExpr->x.pList;
-  if( pList->nExpr!=2 ){
-    return 0;
-  }
-  if( pList->a[1].pExpr->op != TK_COLUMN ){
-    return 0;
-  }
-  return 1;
-}
-#endif /* SQLITE_OMIT_VIRTUALTABLE */
-
-/*
-** If the pBase expression originated in the ON or USING clause of
-** a join, then transfer the appropriate markings over to derived.
-*/
-static void transferJoinMarkings(Expr *pDerived, Expr *pBase){
-  if( pDerived ){
-    pDerived->flags |= pBase->flags & EP_FromJoin;
-    pDerived->iRightJoinTable = pBase->iRightJoinTable;
-  }
-}
-
-#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
-/*
-** Analyze a term that consists of two or more OR-connected
-** subterms.  So in:
-**
-**     ... WHERE  (a=5) AND (b=7 OR c=9 OR d=13) AND (d=13)
-**                          ^^^^^^^^^^^^^^^^^^^^
-**
-** This routine analyzes terms such as the middle term in the above example.
-** A WhereOrTerm object is computed and attached to the term under
-** analysis, regardless of the outcome of the analysis.  Hence:
-**
-**     WhereTerm.wtFlags   |=  TERM_ORINFO
-**     WhereTerm.u.pOrInfo  =  a dynamically allocated WhereOrTerm object
-**
-** The term being analyzed must have two or more of OR-connected subterms.
-** A single subterm might be a set of AND-connected sub-subterms.
-** Examples of terms under analysis:
-**
-**     (A)     t1.x=t2.y OR t1.x=t2.z OR t1.y=15 OR t1.z=t3.a+5
-**     (B)     x=expr1 OR expr2=x OR x=expr3
-**     (C)     t1.x=t2.y OR (t1.x=t2.z AND t1.y=15)
-**     (D)     x=expr1 OR (y>11 AND y<22 AND z LIKE '*hello*')
-**     (E)     (p.a=1 AND q.b=2 AND r.c=3) OR (p.x=4 AND q.y=5 AND r.z=6)
-**
-** CASE 1:
-**
-** If all subterms are of the form T.C=expr for some single column of C and
-** a single table T (as shown in example B above) then create a new virtual
-** term that is an equivalent IN expression.  In other words, if the term
-** being analyzed is:
-**
-**      x = expr1  OR  expr2 = x  OR  x = expr3
-**
-** then create a new virtual term like this:
-**
-**      x IN (expr1,expr2,expr3)
-**
-** CASE 2:
-**
-** If all subterms are indexable by a single table T, then set
-**
-**     WhereTerm.eOperator              =  WO_OR
-**     WhereTerm.u.pOrInfo->indexable  |=  the cursor number for table T
-**
-** A subterm is "indexable" if it is of the form
-** "T.C <op> <expr>" where C is any column of table T and 
-** <op> is one of "=", "<", "<=", ">", ">=", "IS NULL", or "IN".
-** A subterm is also indexable if it is an AND of two or more
-** subsubterms at least one of which is indexable.  Indexable AND 
-** subterms have their eOperator set to WO_AND and they have
-** u.pAndInfo set to a dynamically allocated WhereAndTerm object.
-**
-** From another point of view, "indexable" means that the subterm could
-** potentially be used with an index if an appropriate index exists.
-** This analysis does not consider whether or not the index exists; that
-** is decided elsewhere.  This analysis only looks at whether subterms
-** appropriate for indexing exist.
-**
-** All examples A through E above satisfy case 2.  But if a term
-** also statisfies case 1 (such as B) we know that the optimizer will
-** always prefer case 1, so in that case we pretend that case 2 is not
-** satisfied.
-**
-** It might be the case that multiple tables are indexable.  For example,
-** (E) above is indexable on tables P, Q, and R.
-**
-** Terms that satisfy case 2 are candidates for lookup by using
-** separate indices to find rowids for each subterm and composing
-** the union of all rowids using a RowSet object.  This is similar
-** to "bitmap indices" in other database engines.
-**
-** OTHERWISE:
-**
-** If neither case 1 nor case 2 apply, then leave the eOperator set to
-** zero.  This term is not useful for search.
-*/
-static void exprAnalyzeOrTerm(
-  SrcList *pSrc,            /* the FROM clause */
-  WhereClause *pWC,         /* the complete WHERE clause */
-  int idxTerm               /* Index of the OR-term to be analyzed */
-){
-  WhereInfo *pWInfo = pWC->pWInfo;        /* WHERE clause processing context */
-  Parse *pParse = pWInfo->pParse;         /* Parser context */
-  sqlite3 *db = pParse->db;               /* Database connection */
-  WhereTerm *pTerm = &pWC->a[idxTerm];    /* The term to be analyzed */
-  Expr *pExpr = pTerm->pExpr;             /* The expression of the term */
-  int i;                                  /* Loop counters */
-  WhereClause *pOrWc;       /* Breakup of pTerm into subterms */
-  WhereTerm *pOrTerm;       /* A Sub-term within the pOrWc */
-  WhereOrInfo *pOrInfo;     /* Additional information associated with pTerm */
-  Bitmask chngToIN;         /* Tables that might satisfy case 1 */
-  Bitmask indexable;        /* Tables that are indexable, satisfying case 2 */
-
-  /*
-  ** Break the OR clause into its separate subterms.  The subterms are
-  ** stored in a WhereClause structure containing within the WhereOrInfo
-  ** object that is attached to the original OR clause term.
-  */
-  assert( (pTerm->wtFlags & (TERM_DYNAMIC|TERM_ORINFO|TERM_ANDINFO))==0 );
-  assert( pExpr->op==TK_OR );
-  pTerm->u.pOrInfo = pOrInfo = sqlite3DbMallocZero(db, sizeof(*pOrInfo));
-  if( pOrInfo==0 ) return;
-  pTerm->wtFlags |= TERM_ORINFO;
-  pOrWc = &pOrInfo->wc;
-  whereClauseInit(pOrWc, pWInfo);
-  whereSplit(pOrWc, pExpr, TK_OR);
-  exprAnalyzeAll(pSrc, pOrWc);
-  if( db->mallocFailed ) return;
-  assert( pOrWc->nTerm>=2 );
-
-  /*
-  ** Compute the set of tables that might satisfy cases 1 or 2.
-  */
-  indexable = ~(Bitmask)0;
-  chngToIN = ~(Bitmask)0;
-  for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0 && indexable; i--, pOrTerm++){
-    if( (pOrTerm->eOperator & WO_SINGLE)==0 ){
-      WhereAndInfo *pAndInfo;
-      assert( (pOrTerm->wtFlags & (TERM_ANDINFO|TERM_ORINFO))==0 );
-      chngToIN = 0;
-      pAndInfo = sqlite3DbMallocRaw(db, sizeof(*pAndInfo));
-      if( pAndInfo ){
-        WhereClause *pAndWC;
-        WhereTerm *pAndTerm;
-        int j;
-        Bitmask b = 0;
-        pOrTerm->u.pAndInfo = pAndInfo;
-        pOrTerm->wtFlags |= TERM_ANDINFO;
-        pOrTerm->eOperator = WO_AND;
-        pAndWC = &pAndInfo->wc;
-        whereClauseInit(pAndWC, pWC->pWInfo);
-        whereSplit(pAndWC, pOrTerm->pExpr, TK_AND);
-        exprAnalyzeAll(pSrc, pAndWC);
-        pAndWC->pOuter = pWC;
-        testcase( db->mallocFailed );
-        if( !db->mallocFailed ){
-          for(j=0, pAndTerm=pAndWC->a; j<pAndWC->nTerm; j++, pAndTerm++){
-            assert( pAndTerm->pExpr );
-            if( allowedOp(pAndTerm->pExpr->op) ){
-              b |= getMask(&pWInfo->sMaskSet, pAndTerm->leftCursor);
-            }
-          }
-        }
-        indexable &= b;
-      }
-    }else if( pOrTerm->wtFlags & TERM_COPIED ){
-      /* Skip this term for now.  We revisit it when we process the
-      ** corresponding TERM_VIRTUAL term */
-    }else{
-      Bitmask b;
-      b = getMask(&pWInfo->sMaskSet, pOrTerm->leftCursor);
-      if( pOrTerm->wtFlags & TERM_VIRTUAL ){
-        WhereTerm *pOther = &pOrWc->a[pOrTerm->iParent];
-        b |= getMask(&pWInfo->sMaskSet, pOther->leftCursor);
-      }
-      indexable &= b;
-      if( (pOrTerm->eOperator & WO_EQ)==0 ){
-        chngToIN = 0;
-      }else{
-        chngToIN &= b;
-      }
-    }
-  }
-
-  /*
-  ** Record the set of tables that satisfy case 2.  The set might be
-  ** empty.
-  */
-  pOrInfo->indexable = indexable;
-  pTerm->eOperator = indexable==0 ? 0 : WO_OR;
-
-  /*
-  ** chngToIN holds a set of tables that *might* satisfy case 1.  But
-  ** we have to do some additional checking to see if case 1 really
-  ** is satisfied.
-  **
-  ** chngToIN will hold either 0, 1, or 2 bits.  The 0-bit case means
-  ** that there is no possibility of transforming the OR clause into an
-  ** IN operator because one or more terms in the OR clause contain
-  ** something other than == on a column in the single table.  The 1-bit
-  ** case means that every term of the OR clause is of the form
-  ** "table.column=expr" for some single table.  The one bit that is set
-  ** will correspond to the common table.  We still need to check to make
-  ** sure the same column is used on all terms.  The 2-bit case is when
-  ** the all terms are of the form "table1.column=table2.column".  It
-  ** might be possible to form an IN operator with either table1.column
-  ** or table2.column as the LHS if either is common to every term of
-  ** the OR clause.
-  **
-  ** Note that terms of the form "table.column1=table.column2" (the
-  ** same table on both sizes of the ==) cannot be optimized.
-  */
-  if( chngToIN ){
-    int okToChngToIN = 0;     /* True if the conversion to IN is valid */
-    int iColumn = -1;         /* Column index on lhs of IN operator */
-    int iCursor = -1;         /* Table cursor common to all terms */
-    int j = 0;                /* Loop counter */
-
-    /* Search for a table and column that appears on one side or the
-    ** other of the == operator in every subterm.  That table and column
-    ** will be recorded in iCursor and iColumn.  There might not be any
-    ** such table and column.  Set okToChngToIN if an appropriate table
-    ** and column is found but leave okToChngToIN false if not found.
-    */
-    for(j=0; j<2 && !okToChngToIN; j++){
-      pOrTerm = pOrWc->a;
-      for(i=pOrWc->nTerm-1; i>=0; i--, pOrTerm++){
-        assert( pOrTerm->eOperator & WO_EQ );
-        pOrTerm->wtFlags &= ~TERM_OR_OK;
-        if( pOrTerm->leftCursor==iCursor ){
-          /* This is the 2-bit case and we are on the second iteration and
-          ** current term is from the first iteration.  So skip this term. */
-          assert( j==1 );
-          continue;
-        }
-        if( (chngToIN & getMask(&pWInfo->sMaskSet, pOrTerm->leftCursor))==0 ){
-          /* This term must be of the form t1.a==t2.b where t2 is in the
-          ** chngToIN set but t1 is not.  This term will be either preceeded
-          ** or follwed by an inverted copy (t2.b==t1.a).  Skip this term 
-          ** and use its inversion. */
-          testcase( pOrTerm->wtFlags & TERM_COPIED );
-          testcase( pOrTerm->wtFlags & TERM_VIRTUAL );
-          assert( pOrTerm->wtFlags & (TERM_COPIED|TERM_VIRTUAL) );
-          continue;
-        }
-        iColumn = pOrTerm->u.leftColumn;
-        iCursor = pOrTerm->leftCursor;
-        break;
-      }
-      if( i<0 ){
-        /* No candidate table+column was found.  This can only occur
-        ** on the second iteration */
-        assert( j==1 );
-        assert( IsPowerOfTwo(chngToIN) );
-        assert( chngToIN==getMask(&pWInfo->sMaskSet, iCursor) );
-        break;
-      }
-      testcase( j==1 );
-
-      /* We have found a candidate table and column.  Check to see if that
-      ** table and column is common to every term in the OR clause */
-      okToChngToIN = 1;
-      for(; i>=0 && okToChngToIN; i--, pOrTerm++){
-        assert( pOrTerm->eOperator & WO_EQ );
-        if( pOrTerm->leftCursor!=iCursor ){
-          pOrTerm->wtFlags &= ~TERM_OR_OK;
-        }else if( pOrTerm->u.leftColumn!=iColumn ){
-          okToChngToIN = 0;
-        }else{
-          int affLeft, affRight;
-          /* If the right-hand side is also a column, then the affinities
-          ** of both right and left sides must be such that no type
-          ** conversions are required on the right.  (Ticket #2249)
-          */
-          affRight = sqlite3ExprAffinity(pOrTerm->pExpr->pRight);
-          affLeft = sqlite3ExprAffinity(pOrTerm->pExpr->pLeft);
-          if( affRight!=0 && affRight!=affLeft ){
-            okToChngToIN = 0;
-          }else{
-            pOrTerm->wtFlags |= TERM_OR_OK;
-          }
-        }
-      }
-    }
-
-    /* At this point, okToChngToIN is true if original pTerm satisfies
-    ** case 1.  In that case, construct a new virtual term that is 
-    ** pTerm converted into an IN operator.
-    */
-    if( okToChngToIN ){
-      Expr *pDup;            /* A transient duplicate expression */
-      ExprList *pList = 0;   /* The RHS of the IN operator */
-      Expr *pLeft = 0;       /* The LHS of the IN operator */
-      Expr *pNew;            /* The complete IN operator */
-
-      for(i=pOrWc->nTerm-1, pOrTerm=pOrWc->a; i>=0; i--, pOrTerm++){
-        if( (pOrTerm->wtFlags & TERM_OR_OK)==0 ) continue;
-        assert( pOrTerm->eOperator & WO_EQ );
-        assert( pOrTerm->leftCursor==iCursor );
-        assert( pOrTerm->u.leftColumn==iColumn );
-        pDup = sqlite3ExprDup(db, pOrTerm->pExpr->pRight, 0);
-        pList = sqlite3ExprListAppend(pWInfo->pParse, pList, pDup);
-        pLeft = pOrTerm->pExpr->pLeft;
-      }
-      assert( pLeft!=0 );
-      pDup = sqlite3ExprDup(db, pLeft, 0);
-      pNew = sqlite3PExpr(pParse, TK_IN, pDup, 0, 0);
-      if( pNew ){
-        int idxNew;
-        transferJoinMarkings(pNew, pExpr);
-        assert( !ExprHasProperty(pNew, EP_xIsSelect) );
-        pNew->x.pList = pList;
-        idxNew = whereClauseInsert(pWC, pNew, TERM_VIRTUAL|TERM_DYNAMIC);
-        testcase( idxNew==0 );
-        exprAnalyze(pSrc, pWC, idxNew);
-        pTerm = &pWC->a[idxTerm];
-        pWC->a[idxNew].iParent = idxTerm;
-        pTerm->nChild = 1;
-      }else{
-        sqlite3ExprListDelete(db, pList);
-      }
-      pTerm->eOperator = WO_NOOP;  /* case 1 trumps case 2 */
-    }
-  }
-}
-#endif /* !SQLITE_OMIT_OR_OPTIMIZATION && !SQLITE_OMIT_SUBQUERY */
-
-/*
-** The input to this routine is an WhereTerm structure with only the
-** "pExpr" field filled in.  The job of this routine is to analyze the
-** subexpression and populate all the other fields of the WhereTerm
-** structure.
-**
-** If the expression is of the form "<expr> <op> X" it gets commuted
-** to the standard form of "X <op> <expr>".
-**
-** If the expression is of the form "X <op> Y" where both X and Y are
-** columns, then the original expression is unchanged and a new virtual
-** term of the form "Y <op> X" is added to the WHERE clause and
-** analyzed separately.  The original term is marked with TERM_COPIED
-** and the new term is marked with TERM_DYNAMIC (because it's pExpr
-** needs to be freed with the WhereClause) and TERM_VIRTUAL (because it
-** is a commuted copy of a prior term.)  The original term has nChild=1
-** and the copy has idxParent set to the index of the original term.
-*/
-static void exprAnalyze(
-  SrcList *pSrc,            /* the FROM clause */
-  WhereClause *pWC,         /* the WHERE clause */
-  int idxTerm               /* Index of the term to be analyzed */
-){
-  WhereInfo *pWInfo = pWC->pWInfo; /* WHERE clause processing context */
-  WhereTerm *pTerm;                /* The term to be analyzed */
-  WhereMaskSet *pMaskSet;          /* Set of table index masks */
-  Expr *pExpr;                     /* The expression to be analyzed */
-  Bitmask prereqLeft;              /* Prerequesites of the pExpr->pLeft */
-  Bitmask prereqAll;               /* Prerequesites of pExpr */
-  Bitmask extraRight = 0;          /* Extra dependencies on LEFT JOIN */
-  Expr *pStr1 = 0;                 /* RHS of LIKE/GLOB operator */
-  int isComplete = 0;              /* RHS of LIKE/GLOB ends with wildcard */
-  int noCase = 0;                  /* LIKE/GLOB distinguishes case */
-  int op;                          /* Top-level operator.  pExpr->op */
-  Parse *pParse = pWInfo->pParse;  /* Parsing context */
-  sqlite3 *db = pParse->db;        /* Database connection */
-
-  if( db->mallocFailed ){
-    return;
-  }
-  pTerm = &pWC->a[idxTerm];
-  pMaskSet = &pWInfo->sMaskSet;
-  pExpr = pTerm->pExpr;
-  assert( pExpr->op!=TK_AS && pExpr->op!=TK_COLLATE );
-  prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft);
-  op = pExpr->op;
-  if( op==TK_IN ){
-    assert( pExpr->pRight==0 );
-    if( ExprHasProperty(pExpr, EP_xIsSelect) ){
-      pTerm->prereqRight = exprSelectTableUsage(pMaskSet, pExpr->x.pSelect);
-    }else{
-      pTerm->prereqRight = exprListTableUsage(pMaskSet, pExpr->x.pList);
-    }
-  }else if( op==TK_ISNULL ){
-    pTerm->prereqRight = 0;
-  }else{
-    pTerm->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight);
-  }
-  prereqAll = exprTableUsage(pMaskSet, pExpr);
-  if( ExprHasProperty(pExpr, EP_FromJoin) ){
-    Bitmask x = getMask(pMaskSet, pExpr->iRightJoinTable);
-    prereqAll |= x;
-    extraRight = x-1;  /* ON clause terms may not be used with an index
-                       ** on left table of a LEFT JOIN.  Ticket #3015 */
-  }
-  pTerm->prereqAll = prereqAll;
-  pTerm->leftCursor = -1;
-  pTerm->iParent = -1;
-  pTerm->eOperator = 0;
-  if( allowedOp(op) ){
-    Expr *pLeft = sqlite3ExprSkipCollate(pExpr->pLeft);
-    Expr *pRight = sqlite3ExprSkipCollate(pExpr->pRight);
-    u16 opMask = (pTerm->prereqRight & prereqLeft)==0 ? WO_ALL : WO_EQUIV;
-    if( pLeft->op==TK_COLUMN ){
-      pTerm->leftCursor = pLeft->iTable;
-      pTerm->u.leftColumn = pLeft->iColumn;
-      pTerm->eOperator = operatorMask(op) & opMask;
-    }
-    if( pRight && pRight->op==TK_COLUMN ){
-      WhereTerm *pNew;
-      Expr *pDup;
-      u16 eExtraOp = 0;        /* Extra bits for pNew->eOperator */
-      if( pTerm->leftCursor>=0 ){
-        int idxNew;
-        pDup = sqlite3ExprDup(db, pExpr, 0);
-        if( db->mallocFailed ){
-          sqlite3ExprDelete(db, pDup);
-          return;
-        }
-        idxNew = whereClauseInsert(pWC, pDup, TERM_VIRTUAL|TERM_DYNAMIC);
-        if( idxNew==0 ) return;
-        pNew = &pWC->a[idxNew];
-        pNew->iParent = idxTerm;
-        pTerm = &pWC->a[idxTerm];
-        pTerm->nChild = 1;
-        pTerm->wtFlags |= TERM_COPIED;
-        if( pExpr->op==TK_EQ
-         && !ExprHasProperty(pExpr, EP_FromJoin)
-         && OptimizationEnabled(db, SQLITE_Transitive)
-        ){
-          pTerm->eOperator |= WO_EQUIV;
-          eExtraOp = WO_EQUIV;
-        }
-      }else{
-        pDup = pExpr;
-        pNew = pTerm;
-      }
-      exprCommute(pParse, pDup);
-      pLeft = sqlite3ExprSkipCollate(pDup->pLeft);
-      pNew->leftCursor = pLeft->iTable;
-      pNew->u.leftColumn = pLeft->iColumn;
-      testcase( (prereqLeft | extraRight) != prereqLeft );
-      pNew->prereqRight = prereqLeft | extraRight;
-      pNew->prereqAll = prereqAll;
-      pNew->eOperator = (operatorMask(pDup->op) + eExtraOp) & opMask;
-    }
-  }
-
-#ifndef SQLITE_OMIT_BETWEEN_OPTIMIZATION
-  /* If a term is the BETWEEN operator, create two new virtual terms
-  ** that define the range that the BETWEEN implements.  For example:
-  **
-  **      a BETWEEN b AND c
-  **
-  ** is converted into:
-  **
-  **      (a BETWEEN b AND c) AND (a>=b) AND (a<=c)
-  **
-  ** The two new terms are added onto the end of the WhereClause object.
-  ** The new terms are "dynamic" and are children of the original BETWEEN
-  ** term.  That means that if the BETWEEN term is coded, the children are
-  ** skipped.  Or, if the children are satisfied by an index, the original
-  ** BETWEEN term is skipped.
-  */
-  else if( pExpr->op==TK_BETWEEN && pWC->op==TK_AND ){
-    ExprList *pList = pExpr->x.pList;
-    int i;
-    static const u8 ops[] = {TK_GE, TK_LE};
-    assert( pList!=0 );
-    assert( pList->nExpr==2 );
-    for(i=0; i<2; i++){
-      Expr *pNewExpr;
-      int idxNew;
-      pNewExpr = sqlite3PExpr(pParse, ops[i], 
-                             sqlite3ExprDup(db, pExpr->pLeft, 0),
-                             sqlite3ExprDup(db, pList->a[i].pExpr, 0), 0);
-      transferJoinMarkings(pNewExpr, pExpr);
-      idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
-      testcase( idxNew==0 );
-      exprAnalyze(pSrc, pWC, idxNew);
-      pTerm = &pWC->a[idxTerm];
-      pWC->a[idxNew].iParent = idxTerm;
-    }
-    pTerm->nChild = 2;
-  }
-#endif /* SQLITE_OMIT_BETWEEN_OPTIMIZATION */
-
-#if !defined(SQLITE_OMIT_OR_OPTIMIZATION) && !defined(SQLITE_OMIT_SUBQUERY)
-  /* Analyze a term that is composed of two or more subterms connected by
-  ** an OR operator.
-  */
-  else if( pExpr->op==TK_OR ){
-    assert( pWC->op==TK_AND );
-    exprAnalyzeOrTerm(pSrc, pWC, idxTerm);
-    pTerm = &pWC->a[idxTerm];
-  }
-#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
-
-#ifndef SQLITE_OMIT_LIKE_OPTIMIZATION
-  /* Add constraints to reduce the search space on a LIKE or GLOB
-  ** operator.
-  **
-  ** A like pattern of the form "x LIKE 'abc%'" is changed into constraints
-  **
-  **          x>='abc' AND x<'abd' AND x LIKE 'abc%'
-  **
-  ** The last character of the prefix "abc" is incremented to form the
-  ** termination condition "abd".
-  */
-  if( pWC->op==TK_AND 
-   && isLikeOrGlob(pParse, pExpr, &pStr1, &isComplete, &noCase)
-  ){
-    Expr *pLeft;       /* LHS of LIKE/GLOB operator */
-    Expr *pStr2;       /* Copy of pStr1 - RHS of LIKE/GLOB operator */
-    Expr *pNewExpr1;
-    Expr *pNewExpr2;
-    int idxNew1;
-    int idxNew2;
-    Token sCollSeqName;  /* Name of collating sequence */
-
-    pLeft = pExpr->x.pList->a[1].pExpr;
-    pStr2 = sqlite3ExprDup(db, pStr1, 0);
-    if( !db->mallocFailed ){
-      u8 c, *pC;       /* Last character before the first wildcard */
-      pC = (u8*)&pStr2->u.zToken[sqlite3Strlen30(pStr2->u.zToken)-1];
-      c = *pC;
-      if( noCase ){
-        /* The point is to increment the last character before the first
-        ** wildcard.  But if we increment '@', that will push it into the
-        ** alphabetic range where case conversions will mess up the 
-        ** inequality.  To avoid this, make sure to also run the full
-        ** LIKE on all candidate expressions by clearing the isComplete flag
-        */
-        if( c=='A'-1 ) isComplete = 0;
-        c = sqlite3UpperToLower[c];
-      }
-      *pC = c + 1;
-    }
-    sCollSeqName.z = noCase ? "NOCASE" : "BINARY";
-    sCollSeqName.n = 6;
-    pNewExpr1 = sqlite3ExprDup(db, pLeft, 0);
-    pNewExpr1 = sqlite3PExpr(pParse, TK_GE, 
-           sqlite3ExprAddCollateToken(pParse,pNewExpr1,&sCollSeqName),
-           pStr1, 0);
-    transferJoinMarkings(pNewExpr1, pExpr);
-    idxNew1 = whereClauseInsert(pWC, pNewExpr1, TERM_VIRTUAL|TERM_DYNAMIC);
-    testcase( idxNew1==0 );
-    exprAnalyze(pSrc, pWC, idxNew1);
-    pNewExpr2 = sqlite3ExprDup(db, pLeft, 0);
-    pNewExpr2 = sqlite3PExpr(pParse, TK_LT,
-           sqlite3ExprAddCollateToken(pParse,pNewExpr2,&sCollSeqName),
-           pStr2, 0);
-    transferJoinMarkings(pNewExpr2, pExpr);
-    idxNew2 = whereClauseInsert(pWC, pNewExpr2, TERM_VIRTUAL|TERM_DYNAMIC);
-    testcase( idxNew2==0 );
-    exprAnalyze(pSrc, pWC, idxNew2);
-    pTerm = &pWC->a[idxTerm];
-    if( isComplete ){
-      pWC->a[idxNew1].iParent = idxTerm;
-      pWC->a[idxNew2].iParent = idxTerm;
-      pTerm->nChild = 2;
-    }
-  }
-#endif /* SQLITE_OMIT_LIKE_OPTIMIZATION */
-
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-  /* Add a WO_MATCH auxiliary term to the constraint set if the
-  ** current expression is of the form:  column MATCH expr.
-  ** This information is used by the xBestIndex methods of
-  ** virtual tables.  The native query optimizer does not attempt
-  ** to do anything with MATCH functions.
-  */
-  if( isMatchOfColumn(pExpr) ){
-    int idxNew;
-    Expr *pRight, *pLeft;
-    WhereTerm *pNewTerm;
-    Bitmask prereqColumn, prereqExpr;
-
-    pRight = pExpr->x.pList->a[0].pExpr;
-    pLeft = pExpr->x.pList->a[1].pExpr;
-    prereqExpr = exprTableUsage(pMaskSet, pRight);
-    prereqColumn = exprTableUsage(pMaskSet, pLeft);
-    if( (prereqExpr & prereqColumn)==0 ){
-      Expr *pNewExpr;
-      pNewExpr = sqlite3PExpr(pParse, TK_MATCH, 
-                              0, sqlite3ExprDup(db, pRight, 0), 0);
-      idxNew = whereClauseInsert(pWC, pNewExpr, TERM_VIRTUAL|TERM_DYNAMIC);
-      testcase( idxNew==0 );
-      pNewTerm = &pWC->a[idxNew];
-      pNewTerm->prereqRight = prereqExpr;
-      pNewTerm->leftCursor = pLeft->iTable;
-      pNewTerm->u.leftColumn = pLeft->iColumn;
-      pNewTerm->eOperator = WO_MATCH;
-      pNewTerm->iParent = idxTerm;
-      pTerm = &pWC->a[idxTerm];
-      pTerm->nChild = 1;
-      pTerm->wtFlags |= TERM_COPIED;
-      pNewTerm->prereqAll = pTerm->prereqAll;
-    }
-  }
-#endif /* SQLITE_OMIT_VIRTUALTABLE */
-
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-  /* When sqlite_stat3 histogram data is available an operator of the
-  ** form "x IS NOT NULL" can sometimes be evaluated more efficiently
-  ** as "x>NULL" if x is not an INTEGER PRIMARY KEY.  So construct a
-  ** virtual term of that form.
-  **
-  ** Note that the virtual term must be tagged with TERM_VNULL.  This
-  ** TERM_VNULL tag will suppress the not-null check at the beginning
-  ** of the loop.  Without the TERM_VNULL flag, the not-null check at
-  ** the start of the loop will prevent any results from being returned.
-  */
-  if( pExpr->op==TK_NOTNULL
-   && pExpr->pLeft->op==TK_COLUMN
-   && pExpr->pLeft->iColumn>=0
-   && OptimizationEnabled(db, SQLITE_Stat3)
-  ){
-    Expr *pNewExpr;
-    Expr *pLeft = pExpr->pLeft;
-    int idxNew;
-    WhereTerm *pNewTerm;
-
-    pNewExpr = sqlite3PExpr(pParse, TK_GT,
-                            sqlite3ExprDup(db, pLeft, 0),
-                            sqlite3PExpr(pParse, TK_NULL, 0, 0, 0), 0);
-
-    idxNew = whereClauseInsert(pWC, pNewExpr,
-                              TERM_VIRTUAL|TERM_DYNAMIC|TERM_VNULL);
-    if( idxNew ){
-      pNewTerm = &pWC->a[idxNew];
-      pNewTerm->prereqRight = 0;
-      pNewTerm->leftCursor = pLeft->iTable;
-      pNewTerm->u.leftColumn = pLeft->iColumn;
-      pNewTerm->eOperator = WO_GT;
-      pNewTerm->iParent = idxTerm;
-      pTerm = &pWC->a[idxTerm];
-      pTerm->nChild = 1;
-      pTerm->wtFlags |= TERM_COPIED;
-      pNewTerm->prereqAll = pTerm->prereqAll;
-    }
-  }
-#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
-
-  /* Prevent ON clause terms of a LEFT JOIN from being used to drive
-  ** an index for tables to the left of the join.
-  */
-  pTerm->prereqRight |= extraRight;
-}
-
-/*
-** This function searches pList for a entry that matches the iCol-th column
-** of index pIdx.
-**
-** If such an expression is found, its index in pList->a[] is returned. If
-** no expression is found, -1 is returned.
-*/
-static int findIndexCol(
-  Parse *pParse,                  /* Parse context */
-  ExprList *pList,                /* Expression list to search */
-  int iBase,                      /* Cursor for table associated with pIdx */
-  Index *pIdx,                    /* Index to match column of */
-  int iCol                        /* Column of index to match */
-){
-  int i;
-  const char *zColl = pIdx->azColl[iCol];
-
-  for(i=0; i<pList->nExpr; i++){
-    Expr *p = sqlite3ExprSkipCollate(pList->a[i].pExpr);
-    if( p->op==TK_COLUMN
-     && p->iColumn==pIdx->aiColumn[iCol]
-     && p->iTable==iBase
-    ){
-      CollSeq *pColl = sqlite3ExprCollSeq(pParse, pList->a[i].pExpr);
-      if( ALWAYS(pColl) && 0==sqlite3StrICmp(pColl->zName, zColl) ){
-        return i;
-      }
-    }
-  }
-
-  return -1;
-}
-
-/*
-** Return true if the DISTINCT expression-list passed as the third argument
-** is redundant.
-**
-** A DISTINCT list is redundant if the database contains some subset of
-** columns that are unique and non-null.
-*/
-static int isDistinctRedundant(
-  Parse *pParse,            /* Parsing context */
-  SrcList *pTabList,        /* The FROM clause */
-  WhereClause *pWC,         /* The WHERE clause */
-  ExprList *pDistinct       /* The result set that needs to be DISTINCT */
-){
-  Table *pTab;
-  Index *pIdx;
-  int i;                          
-  int iBase;
-
-  /* If there is more than one table or sub-select in the FROM clause of
-  ** this query, then it will not be possible to show that the DISTINCT 
-  ** clause is redundant. */
-  if( pTabList->nSrc!=1 ) return 0;
-  iBase = pTabList->a[0].iCursor;
-  pTab = pTabList->a[0].pTab;
-
-  /* If any of the expressions is an IPK column on table iBase, then return 
-  ** true. Note: The (p->iTable==iBase) part of this test may be false if the
-  ** current SELECT is a correlated sub-query.
-  */
-  for(i=0; i<pDistinct->nExpr; i++){
-    Expr *p = sqlite3ExprSkipCollate(pDistinct->a[i].pExpr);
-    if( p->op==TK_COLUMN && p->iTable==iBase && p->iColumn<0 ) return 1;
-  }
-
-  /* Loop through all indices on the table, checking each to see if it makes
-  ** the DISTINCT qualifier redundant. It does so if:
-  **
-  **   1. The index is itself UNIQUE, and
-  **
-  **   2. All of the columns in the index are either part of the pDistinct
-  **      list, or else the WHERE clause contains a term of the form "col=X",
-  **      where X is a constant value. The collation sequences of the
-  **      comparison and select-list expressions must match those of the index.
-  **
-  **   3. All of those index columns for which the WHERE clause does not
-  **      contain a "col=X" term are subject to a NOT NULL constraint.
-  */
-  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
-    if( pIdx->onError==OE_None ) continue;
-    for(i=0; i<pIdx->nColumn; i++){
-      int iCol = pIdx->aiColumn[i];
-      if( 0==findTerm(pWC, iBase, iCol, ~(Bitmask)0, WO_EQ, pIdx) ){
-        int iIdxCol = findIndexCol(pParse, pDistinct, iBase, pIdx, i);
-        if( iIdxCol<0 || pTab->aCol[pIdx->aiColumn[i]].notNull==0 ){
-          break;
-        }
-      }
-    }
-    if( i==pIdx->nColumn ){
-      /* This index implies that the DISTINCT qualifier is redundant. */
-      return 1;
-    }
-  }
-
-  return 0;
-}
-
-
-/*
-** Estimate the logarithm of the input value to base 2.
-*/
-static LogEst estLog(LogEst N){
-  LogEst x = sqlite3LogEst(N);
-  return x>33 ? x - 33 : 0;
-}
-
-/*
-** Two routines for printing the content of an sqlite3_index_info
-** structure.  Used for testing and debugging only.  If neither
-** SQLITE_TEST or SQLITE_DEBUG are defined, then these routines
-** are no-ops.
-*/
-#if !defined(SQLITE_OMIT_VIRTUALTABLE) && defined(WHERETRACE_ENABLED)
-static void TRACE_IDX_INPUTS(sqlite3_index_info *p){
-  int i;
-  if( !sqlite3WhereTrace ) return;
-  for(i=0; i<p->nConstraint; i++){
-    sqlite3DebugPrintf("  constraint[%d]: col=%d termid=%d op=%d usabled=%d\n",
-       i,
-       p->aConstraint[i].iColumn,
-       p->aConstraint[i].iTermOffset,
-       p->aConstraint[i].op,
-       p->aConstraint[i].usable);
-  }
-  for(i=0; i<p->nOrderBy; i++){
-    sqlite3DebugPrintf("  orderby[%d]: col=%d desc=%d\n",
-       i,
-       p->aOrderBy[i].iColumn,
-       p->aOrderBy[i].desc);
-  }
-}
-static void TRACE_IDX_OUTPUTS(sqlite3_index_info *p){
-  int i;
-  if( !sqlite3WhereTrace ) return;
-  for(i=0; i<p->nConstraint; i++){
-    sqlite3DebugPrintf("  usage[%d]: argvIdx=%d omit=%d\n",
-       i,
-       p->aConstraintUsage[i].argvIndex,
-       p->aConstraintUsage[i].omit);
-  }
-  sqlite3DebugPrintf("  idxNum=%d\n", p->idxNum);
-  sqlite3DebugPrintf("  idxStr=%s\n", p->idxStr);
-  sqlite3DebugPrintf("  orderByConsumed=%d\n", p->orderByConsumed);
-  sqlite3DebugPrintf("  estimatedCost=%g\n", p->estimatedCost);
-}
-#else
-#define TRACE_IDX_INPUTS(A)
-#define TRACE_IDX_OUTPUTS(A)
-#endif
-
-#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
-/*
-** Return TRUE if the WHERE clause term pTerm is of a form where it
-** could be used with an index to access pSrc, assuming an appropriate
-** index existed.
-*/
-static int termCanDriveIndex(
-  WhereTerm *pTerm,              /* WHERE clause term to check */
-  struct SrcList_item *pSrc,     /* Table we are trying to access */
-  Bitmask notReady               /* Tables in outer loops of the join */
-){
-  char aff;
-  if( pTerm->leftCursor!=pSrc->iCursor ) return 0;
-  if( (pTerm->eOperator & WO_EQ)==0 ) return 0;
-  if( (pTerm->prereqRight & notReady)!=0 ) return 0;
-  if( pTerm->u.leftColumn<0 ) return 0;
-  aff = pSrc->pTab->aCol[pTerm->u.leftColumn].affinity;
-  if( !sqlite3IndexAffinityOk(pTerm->pExpr, aff) ) return 0;
-  return 1;
-}
-#endif
-
-
-#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
-/*
-** Generate code to construct the Index object for an automatic index
-** and to set up the WhereLevel object pLevel so that the code generator
-** makes use of the automatic index.
-*/
-static void constructAutomaticIndex(
-  Parse *pParse,              /* The parsing context */
-  WhereClause *pWC,           /* The WHERE clause */
-  struct SrcList_item *pSrc,  /* The FROM clause term to get the next index */
-  Bitmask notReady,           /* Mask of cursors that are not available */
-  WhereLevel *pLevel          /* Write new index here */
-){
-  int nColumn;                /* Number of columns in the constructed index */
-  WhereTerm *pTerm;           /* A single term of the WHERE clause */
-  WhereTerm *pWCEnd;          /* End of pWC->a[] */
-  int nByte;                  /* Byte of memory needed for pIdx */
-  Index *pIdx;                /* Object describing the transient index */
-  Vdbe *v;                    /* Prepared statement under construction */
-  int addrInit;               /* Address of the initialization bypass jump */
-  Table *pTable;              /* The table being indexed */
-  KeyInfo *pKeyinfo;          /* Key information for the index */   
-  int addrTop;                /* Top of the index fill loop */
-  int regRecord;              /* Register holding an index record */
-  int n;                      /* Column counter */
-  int i;                      /* Loop counter */
-  int mxBitCol;               /* Maximum column in pSrc->colUsed */
-  CollSeq *pColl;             /* Collating sequence to on a column */
-  WhereLoop *pLoop;           /* The Loop object */
-  Bitmask idxCols;            /* Bitmap of columns used for indexing */
-  Bitmask extraCols;          /* Bitmap of additional columns */
-  u8 sentWarning = 0;         /* True if a warnning has been issued */
-
-  /* Generate code to skip over the creation and initialization of the
-  ** transient index on 2nd and subsequent iterations of the loop. */
-  v = pParse->pVdbe;
-  assert( v!=0 );
-  addrInit = sqlite3CodeOnce(pParse);
-
-  /* Count the number of columns that will be added to the index
-  ** and used to match WHERE clause constraints */
-  nColumn = 0;
-  pTable = pSrc->pTab;
-  pWCEnd = &pWC->a[pWC->nTerm];
-  pLoop = pLevel->pWLoop;
-  idxCols = 0;
-  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
-    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
-      int iCol = pTerm->u.leftColumn;
-      Bitmask cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol);
-      testcase( iCol==BMS );
-      testcase( iCol==BMS-1 );
-      if( !sentWarning ){
-        sqlite3_log(SQLITE_WARNING_AUTOINDEX,
-            "automatic index on %s(%s)", pTable->zName,
-            pTable->aCol[iCol].zName);
-        sentWarning = 1;
-      }
-      if( (idxCols & cMask)==0 ){
-        if( whereLoopResize(pParse->db, pLoop, nColumn+1) ) return;
-        pLoop->aLTerm[nColumn++] = pTerm;
-        idxCols |= cMask;
-      }
-    }
-  }
-  assert( nColumn>0 );
-  pLoop->u.btree.nEq = pLoop->nLTerm = nColumn;
-  pLoop->wsFlags = WHERE_COLUMN_EQ | WHERE_IDX_ONLY | WHERE_INDEXED
-                     | WHERE_AUTO_INDEX;
-
-  /* Count the number of additional columns needed to create a
-  ** covering index.  A "covering index" is an index that contains all
-  ** columns that are needed by the query.  With a covering index, the
-  ** original table never needs to be accessed.  Automatic indices must
-  ** be a covering index because the index will not be updated if the
-  ** original table changes and the index and table cannot both be used
-  ** if they go out of sync.
-  */
-  extraCols = pSrc->colUsed & (~idxCols | MASKBIT(BMS-1));
-  mxBitCol = (pTable->nCol >= BMS-1) ? BMS-1 : pTable->nCol;
-  testcase( pTable->nCol==BMS-1 );
-  testcase( pTable->nCol==BMS-2 );
-  for(i=0; i<mxBitCol; i++){
-    if( extraCols & MASKBIT(i) ) nColumn++;
-  }
-  if( pSrc->colUsed & MASKBIT(BMS-1) ){
-    nColumn += pTable->nCol - BMS + 1;
-  }
-  pLoop->wsFlags |= WHERE_COLUMN_EQ | WHERE_IDX_ONLY;
-
-  /* Construct the Index object to describe this index */
-  nByte = sizeof(Index);
-  nByte += nColumn*sizeof(int);     /* Index.aiColumn */
-  nByte += nColumn*sizeof(char*);   /* Index.azColl */
-  nByte += nColumn;                 /* Index.aSortOrder */
-  pIdx = sqlite3DbMallocZero(pParse->db, nByte);
-  if( pIdx==0 ) return;
-  pLoop->u.btree.pIndex = pIdx;
-  pIdx->azColl = (char**)&pIdx[1];
-  pIdx->aiColumn = (int*)&pIdx->azColl[nColumn];
-  pIdx->aSortOrder = (u8*)&pIdx->aiColumn[nColumn];
-  pIdx->zName = "auto-index";
-  pIdx->nColumn = nColumn;
-  pIdx->pTable = pTable;
-  n = 0;
-  idxCols = 0;
-  for(pTerm=pWC->a; pTerm<pWCEnd; pTerm++){
-    if( termCanDriveIndex(pTerm, pSrc, notReady) ){
-      int iCol = pTerm->u.leftColumn;
-      Bitmask cMask = iCol>=BMS ? MASKBIT(BMS-1) : MASKBIT(iCol);
-      testcase( iCol==BMS-1 );
-      testcase( iCol==BMS );
-      if( (idxCols & cMask)==0 ){
-        Expr *pX = pTerm->pExpr;
-        idxCols |= cMask;
-        pIdx->aiColumn[n] = pTerm->u.leftColumn;
-        pColl = sqlite3BinaryCompareCollSeq(pParse, pX->pLeft, pX->pRight);
-        pIdx->azColl[n] = ALWAYS(pColl) ? pColl->zName : "BINARY";
-        n++;
-      }
-    }
-  }
-  assert( (u32)n==pLoop->u.btree.nEq );
-
-  /* Add additional columns needed to make the automatic index into
-  ** a covering index */
-  for(i=0; i<mxBitCol; i++){
-    if( extraCols & MASKBIT(i) ){
-      pIdx->aiColumn[n] = i;
-      pIdx->azColl[n] = "BINARY";
-      n++;
-    }
-  }
-  if( pSrc->colUsed & MASKBIT(BMS-1) ){
-    for(i=BMS-1; i<pTable->nCol; i++){
-      pIdx->aiColumn[n] = i;
-      pIdx->azColl[n] = "BINARY";
-      n++;
-    }
-  }
-  assert( n==nColumn );
-
-  /* Create the automatic index */
-  pKeyinfo = sqlite3IndexKeyinfo(pParse, pIdx);
-  assert( pLevel->iIdxCur>=0 );
-  pLevel->iIdxCur = pParse->nTab++;
-  sqlite3VdbeAddOp4(v, OP_OpenAutoindex, pLevel->iIdxCur, nColumn+1, 0,
-                    (char*)pKeyinfo, P4_KEYINFO_HANDOFF);
-  VdbeComment((v, "for %s", pTable->zName));
-
-  /* Fill the automatic index with content */
-  addrTop = sqlite3VdbeAddOp1(v, OP_Rewind, pLevel->iTabCur);
-  regRecord = sqlite3GetTempReg(pParse);
-  sqlite3GenerateIndexKey(pParse, pIdx, pLevel->iTabCur, regRecord, 1, 0);
-  sqlite3VdbeAddOp2(v, OP_IdxInsert, pLevel->iIdxCur, regRecord);
-  sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
-  sqlite3VdbeAddOp2(v, OP_Next, pLevel->iTabCur, addrTop+1);
-  sqlite3VdbeChangeP5(v, SQLITE_STMTSTATUS_AUTOINDEX);
-  sqlite3VdbeJumpHere(v, addrTop);
-  sqlite3ReleaseTempReg(pParse, regRecord);
-  
-  /* Jump here when skipping the initialization */
-  sqlite3VdbeJumpHere(v, addrInit);
-}
-#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
-
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-/*
-** Allocate and populate an sqlite3_index_info structure. It is the 
-** responsibility of the caller to eventually release the structure
-** by passing the pointer returned by this function to sqlite3_free().
-*/
-static sqlite3_index_info *allocateIndexInfo(
-  Parse *pParse,
-  WhereClause *pWC,
-  struct SrcList_item *pSrc,
-  ExprList *pOrderBy
-){
-  int i, j;
-  int nTerm;
-  struct sqlite3_index_constraint *pIdxCons;
-  struct sqlite3_index_orderby *pIdxOrderBy;
-  struct sqlite3_index_constraint_usage *pUsage;
-  WhereTerm *pTerm;
-  int nOrderBy;
-  sqlite3_index_info *pIdxInfo;
-
-  /* Count the number of possible WHERE clause constraints referring
-  ** to this virtual table */
-  for(i=nTerm=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
-    if( pTerm->leftCursor != pSrc->iCursor ) continue;
-    assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
-    testcase( pTerm->eOperator & WO_IN );
-    testcase( pTerm->eOperator & WO_ISNULL );
-    if( pTerm->eOperator & (WO_ISNULL) ) continue;
-    if( pTerm->wtFlags & TERM_VNULL ) continue;
-    nTerm++;
-  }
-
-  /* If the ORDER BY clause contains only columns in the current 
-  ** virtual table then allocate space for the aOrderBy part of
-  ** the sqlite3_index_info structure.
-  */
-  nOrderBy = 0;
-  if( pOrderBy ){
-    int n = pOrderBy->nExpr;
-    for(i=0; i<n; i++){
-      Expr *pExpr = pOrderBy->a[i].pExpr;
-      if( pExpr->op!=TK_COLUMN || pExpr->iTable!=pSrc->iCursor ) break;
-    }
-    if( i==n){
-      nOrderBy = n;
-    }
-  }
-
-  /* Allocate the sqlite3_index_info structure
-  */
-  pIdxInfo = sqlite3DbMallocZero(pParse->db, sizeof(*pIdxInfo)
-                           + (sizeof(*pIdxCons) + sizeof(*pUsage))*nTerm
-                           + sizeof(*pIdxOrderBy)*nOrderBy );
-  if( pIdxInfo==0 ){
-    sqlite3ErrorMsg(pParse, "out of memory");
-    return 0;
-  }
-
-  /* Initialize the structure.  The sqlite3_index_info structure contains
-  ** many fields that are declared "const" to prevent xBestIndex from
-  ** changing them.  We have to do some funky casting in order to
-  ** initialize those fields.
-  */
-  pIdxCons = (struct sqlite3_index_constraint*)&pIdxInfo[1];
-  pIdxOrderBy = (struct sqlite3_index_orderby*)&pIdxCons[nTerm];
-  pUsage = (struct sqlite3_index_constraint_usage*)&pIdxOrderBy[nOrderBy];
-  *(int*)&pIdxInfo->nConstraint = nTerm;
-  *(int*)&pIdxInfo->nOrderBy = nOrderBy;
-  *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint = pIdxCons;
-  *(struct sqlite3_index_orderby**)&pIdxInfo->aOrderBy = pIdxOrderBy;
-  *(struct sqlite3_index_constraint_usage**)&pIdxInfo->aConstraintUsage =
-                                                                   pUsage;
-
-  for(i=j=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
-    u8 op;
-    if( pTerm->leftCursor != pSrc->iCursor ) continue;
-    assert( IsPowerOfTwo(pTerm->eOperator & ~WO_EQUIV) );
-    testcase( pTerm->eOperator & WO_IN );
-    testcase( pTerm->eOperator & WO_ISNULL );
-    if( pTerm->eOperator & (WO_ISNULL) ) continue;
-    if( pTerm->wtFlags & TERM_VNULL ) continue;
-    pIdxCons[j].iColumn = pTerm->u.leftColumn;
-    pIdxCons[j].iTermOffset = i;
-    op = (u8)pTerm->eOperator & WO_ALL;
-    if( op==WO_IN ) op = WO_EQ;
-    pIdxCons[j].op = op;
-    /* The direct assignment in the previous line is possible only because
-    ** the WO_ and SQLITE_INDEX_CONSTRAINT_ codes are identical.  The
-    ** following asserts verify this fact. */
-    assert( WO_EQ==SQLITE_INDEX_CONSTRAINT_EQ );
-    assert( WO_LT==SQLITE_INDEX_CONSTRAINT_LT );
-    assert( WO_LE==SQLITE_INDEX_CONSTRAINT_LE );
-    assert( WO_GT==SQLITE_INDEX_CONSTRAINT_GT );
-    assert( WO_GE==SQLITE_INDEX_CONSTRAINT_GE );
-    assert( WO_MATCH==SQLITE_INDEX_CONSTRAINT_MATCH );
-    assert( pTerm->eOperator & (WO_IN|WO_EQ|WO_LT|WO_LE|WO_GT|WO_GE|WO_MATCH) );
-    j++;
-  }
-  for(i=0; i<nOrderBy; i++){
-    Expr *pExpr = pOrderBy->a[i].pExpr;
-    pIdxOrderBy[i].iColumn = pExpr->iColumn;
-    pIdxOrderBy[i].desc = pOrderBy->a[i].sortOrder;
-  }
-
-  return pIdxInfo;
-}
-
-/*
-** The table object reference passed as the second argument to this function
-** must represent a virtual table. This function invokes the xBestIndex()
-** method of the virtual table with the sqlite3_index_info object that
-** comes in as the 3rd argument to this function.
-**
-** If an error occurs, pParse is populated with an error message and a
-** non-zero value is returned. Otherwise, 0 is returned and the output
-** part of the sqlite3_index_info structure is left populated.
-**
-** Whether or not an error is returned, it is the responsibility of the
-** caller to eventually free p->idxStr if p->needToFreeIdxStr indicates
-** that this is required.
-*/
-static int vtabBestIndex(Parse *pParse, Table *pTab, sqlite3_index_info *p){
-  sqlite3_vtab *pVtab = sqlite3GetVTable(pParse->db, pTab)->pVtab;
-  int i;
-  int rc;
-
-  TRACE_IDX_INPUTS(p);
-  rc = pVtab->pModule->xBestIndex(pVtab, p);
-  TRACE_IDX_OUTPUTS(p);
-
-  if( rc!=SQLITE_OK ){
-    if( rc==SQLITE_NOMEM ){
-      pParse->db->mallocFailed = 1;
-    }else if( !pVtab->zErrMsg ){
-      sqlite3ErrorMsg(pParse, "%s", sqlite3ErrStr(rc));
-    }else{
-      sqlite3ErrorMsg(pParse, "%s", pVtab->zErrMsg);
-    }
-  }
-  sqlite3_free(pVtab->zErrMsg);
-  pVtab->zErrMsg = 0;
-
-  for(i=0; i<p->nConstraint; i++){
-    if( !p->aConstraint[i].usable && p->aConstraintUsage[i].argvIndex>0 ){
-      sqlite3ErrorMsg(pParse, 
-          "table %s: xBestIndex returned an invalid plan", pTab->zName);
-    }
-  }
-
-  return pParse->nErr;
-}
-#endif /* !defined(SQLITE_OMIT_VIRTUALTABLE) */
-
-
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-/*
-** Estimate the location of a particular key among all keys in an
-** index.  Store the results in aStat as follows:
-**
-**    aStat[0]      Est. number of rows less than pVal
-**    aStat[1]      Est. number of rows equal to pVal
-**
-** Return SQLITE_OK on success.
-*/
-static void whereKeyStats(
-  Parse *pParse,              /* Database connection */
-  Index *pIdx,                /* Index to consider domain of */
-  UnpackedRecord *pRec,       /* Vector of values to consider */
-  int roundUp,                /* Round up if true.  Round down if false */
-  tRowcnt *aStat              /* OUT: stats written here */
-){
-  IndexSample *aSample = pIdx->aSample;
-  int iCol;                   /* Index of required stats in anEq[] etc. */
-  int iMin = 0;               /* Smallest sample not yet tested */
-  int i = pIdx->nSample;      /* Smallest sample larger than or equal to pRec */
-  int iTest;                  /* Next sample to test */
-  int res;                    /* Result of comparison operation */
-
-#ifndef SQLITE_DEBUG
-  UNUSED_PARAMETER( pParse );
-#endif
-  assert( pRec!=0 || pParse->db->mallocFailed );
-  if( pRec==0 ) return;
-  iCol = pRec->nField - 1;
-  assert( pIdx->nSample>0 );
-  assert( pRec->nField>0 && iCol<pIdx->nSampleCol );
-  do{
-    iTest = (iMin+i)/2;
-    res = sqlite3VdbeRecordCompare(aSample[iTest].n, aSample[iTest].p, pRec);
-    if( res<0 ){
-      iMin = iTest+1;
-    }else{
-      i = iTest;
-    }
-  }while( res && iMin<i );
-
-#ifdef SQLITE_DEBUG
-  /* The following assert statements check that the binary search code
-  ** above found the right answer. This block serves no purpose other
-  ** than to invoke the asserts.  */
-  if( res==0 ){
-    /* If (res==0) is true, then sample $i must be equal to pRec */
-    assert( i<pIdx->nSample );
-    assert( 0==sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)
-         || pParse->db->mallocFailed );
-  }else{
-    /* Otherwise, pRec must be smaller than sample $i and larger than
-    ** sample ($i-1).  */
-    assert( i==pIdx->nSample 
-         || sqlite3VdbeRecordCompare(aSample[i].n, aSample[i].p, pRec)>0
-         || pParse->db->mallocFailed );
-    assert( i==0
-         || sqlite3VdbeRecordCompare(aSample[i-1].n, aSample[i-1].p, pRec)<0
-         || pParse->db->mallocFailed );
-  }
-#endif /* ifdef SQLITE_DEBUG */
-
-  /* At this point, aSample[i] is the first sample that is greater than
-  ** or equal to pVal.  Or if i==pIdx->nSample, then all samples are less
-  ** than pVal.  If aSample[i]==pVal, then res==0.
-  */
-  if( res==0 ){
-    aStat[0] = aSample[i].anLt[iCol];
-    aStat[1] = aSample[i].anEq[iCol];
-  }else{
-    tRowcnt iLower, iUpper, iGap;
-    if( i==0 ){
-      iLower = 0;
-      iUpper = aSample[0].anLt[iCol];
-    }else{
-      iUpper = i>=pIdx->nSample ? pIdx->aiRowEst[0] : aSample[i].anLt[iCol];
-      iLower = aSample[i-1].anEq[iCol] + aSample[i-1].anLt[iCol];
-    }
-    aStat[1] = (pIdx->nColumn>iCol ? pIdx->aAvgEq[iCol] : 1);
-    if( iLower>=iUpper ){
-      iGap = 0;
-    }else{
-      iGap = iUpper - iLower;
-    }
-    if( roundUp ){
-      iGap = (iGap*2)/3;
-    }else{
-      iGap = iGap/3;
-    }
-    aStat[0] = iLower + iGap;
-  }
-}
-#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
-
-/*
-** This function is used to estimate the number of rows that will be visited
-** by scanning an index for a range of values. The range may have an upper
-** bound, a lower bound, or both. The WHERE clause terms that set the upper
-** and lower bounds are represented by pLower and pUpper respectively. For
-** example, assuming that index p is on t1(a):
-**
-**   ... FROM t1 WHERE a > ? AND a < ? ...
-**                    |_____|   |_____|
-**                       |         |
-**                     pLower    pUpper
-**
-** If either of the upper or lower bound is not present, then NULL is passed in
-** place of the corresponding WhereTerm.
-**
-** The value in (pBuilder->pNew->u.btree.nEq) is the index of the index
-** column subject to the range constraint. Or, equivalently, the number of
-** equality constraints optimized by the proposed index scan. For example,
-** assuming index p is on t1(a, b), and the SQL query is:
-**
-**   ... FROM t1 WHERE a = ? AND b > ? AND b < ? ...
-**
-** then nEq is set to 1 (as the range restricted column, b, is the second 
-** left-most column of the index). Or, if the query is:
-**
-**   ... FROM t1 WHERE a > ? AND a < ? ...
-**
-** then nEq is set to 0.
-**
-** When this function is called, *pnOut is set to the sqlite3LogEst() of the
-** number of rows that the index scan is expected to visit without 
-** considering the range constraints. If nEq is 0, this is the number of 
-** rows in the index. Assuming no error occurs, *pnOut is adjusted (reduced)
-** to account for the range contraints pLower and pUpper.
-** 
-** In the absence of sqlite_stat4 ANALYZE data, or if such data cannot be
-** used, each range inequality reduces the search space by a factor of 4. 
-** Hence a pair of constraints (x>? AND x<?) reduces the expected number of
-** rows visited by a factor of 16.
-*/
-static int whereRangeScanEst(
-  Parse *pParse,       /* Parsing & code generating context */
-  WhereLoopBuilder *pBuilder,
-  WhereTerm *pLower,   /* Lower bound on the range. ex: "x>123" Might be NULL */
-  WhereTerm *pUpper,   /* Upper bound on the range. ex: "x<455" Might be NULL */
-  WhereLoop *pLoop     /* Modify the .nOut and maybe .rRun fields */
-){
-  int rc = SQLITE_OK;
-  int nOut = pLoop->nOut;
-  LogEst nNew;
-
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-  Index *p = pLoop->u.btree.pIndex;
-  int nEq = pLoop->u.btree.nEq;
-
-  if( p->nSample>0
-   && nEq==pBuilder->nRecValid
-   && nEq<p->nSampleCol
-   && OptimizationEnabled(pParse->db, SQLITE_Stat3) 
-  ){
-    UnpackedRecord *pRec = pBuilder->pRec;
-    tRowcnt a[2];
-    u8 aff;
-
-    /* Variable iLower will be set to the estimate of the number of rows in 
-    ** the index that are less than the lower bound of the range query. The
-    ** lower bound being the concatenation of $P and $L, where $P is the
-    ** key-prefix formed by the nEq values matched against the nEq left-most
-    ** columns of the index, and $L is the value in pLower.
-    **
-    ** Or, if pLower is NULL or $L cannot be extracted from it (because it
-    ** is not a simple variable or literal value), the lower bound of the
-    ** range is $P. Due to a quirk in the way whereKeyStats() works, even
-    ** if $L is available, whereKeyStats() is called for both ($P) and 
-    ** ($P:$L) and the larger of the two returned values used.
-    **
-    ** Similarly, iUpper is to be set to the estimate of the number of rows
-    ** less than the upper bound of the range query. Where the upper bound
-    ** is either ($P) or ($P:$U). Again, even if $U is available, both values
-    ** of iUpper are requested of whereKeyStats() and the smaller used.
-    */
-    tRowcnt iLower;
-    tRowcnt iUpper;
-
-    if( nEq==p->nColumn ){
-      aff = SQLITE_AFF_INTEGER;
-    }else{
-      aff = p->pTable->aCol[p->aiColumn[nEq]].affinity;
-    }
-    /* Determine iLower and iUpper using ($P) only. */
-    if( nEq==0 ){
-      iLower = 0;
-      iUpper = p->aiRowEst[0];
-    }else{
-      /* Note: this call could be optimized away - since the same values must 
-      ** have been requested when testing key $P in whereEqualScanEst().  */
-      whereKeyStats(pParse, p, pRec, 0, a);
-      iLower = a[0];
-      iUpper = a[0] + a[1];
-    }
-
-    /* If possible, improve on the iLower estimate using ($P:$L). */
-    if( pLower ){
-      int bOk;                    /* True if value is extracted from pExpr */
-      Expr *pExpr = pLower->pExpr->pRight;
-      assert( (pLower->eOperator & (WO_GT|WO_GE))!=0 );
-      rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
-      if( rc==SQLITE_OK && bOk ){
-        tRowcnt iNew;
-        whereKeyStats(pParse, p, pRec, 0, a);
-        iNew = a[0] + ((pLower->eOperator & WO_GT) ? a[1] : 0);
-        if( iNew>iLower ) iLower = iNew;
-        nOut--;
-      }
-    }
-
-    /* If possible, improve on the iUpper estimate using ($P:$U). */
-    if( pUpper ){
-      int bOk;                    /* True if value is extracted from pExpr */
-      Expr *pExpr = pUpper->pExpr->pRight;
-      assert( (pUpper->eOperator & (WO_LT|WO_LE))!=0 );
-      rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq, &bOk);
-      if( rc==SQLITE_OK && bOk ){
-        tRowcnt iNew;
-        whereKeyStats(pParse, p, pRec, 1, a);
-        iNew = a[0] + ((pUpper->eOperator & WO_LE) ? a[1] : 0);
-        if( iNew<iUpper ) iUpper = iNew;
-        nOut--;
-      }
-    }
-
-    pBuilder->pRec = pRec;
-    if( rc==SQLITE_OK ){
-      if( iUpper>iLower ){
-        nNew = sqlite3LogEst(iUpper - iLower);
-      }else{
-        nNew = 10;        assert( 10==sqlite3LogEst(2) );
-      }
-      if( nNew<nOut ){
-        nOut = nNew;
-      }
-      pLoop->nOut = (LogEst)nOut;
-      WHERETRACE(0x100, ("range scan regions: %u..%u  est=%d\n",
-                         (u32)iLower, (u32)iUpper, nOut));
-      return SQLITE_OK;
-    }
-  }
-#else
-  UNUSED_PARAMETER(pParse);
-  UNUSED_PARAMETER(pBuilder);
-#endif
-  assert( pLower || pUpper );
-  /* TUNING:  Each inequality constraint reduces the search space 4-fold.
-  ** A BETWEEN operator, therefore, reduces the search space 16-fold */
-  nNew = nOut;
-  if( pLower && (pLower->wtFlags & TERM_VNULL)==0 ){
-    nNew -= 20;        assert( 20==sqlite3LogEst(4) );
-    nOut--;
-  }
-  if( pUpper ){
-    nNew -= 20;        assert( 20==sqlite3LogEst(4) );
-    nOut--;
-  }
-  if( nNew<10 ) nNew = 10;
-  if( nNew<nOut ) nOut = nNew;
-  pLoop->nOut = (LogEst)nOut;
-  return rc;
-}
-
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-/*
-** Estimate the number of rows that will be returned based on
-** an equality constraint x=VALUE and where that VALUE occurs in
-** the histogram data.  This only works when x is the left-most
-** column of an index and sqlite_stat3 histogram data is available
-** for that index.  When pExpr==NULL that means the constraint is
-** "x IS NULL" instead of "x=VALUE".
-**
-** Write the estimated row count into *pnRow and return SQLITE_OK. 
-** If unable to make an estimate, leave *pnRow unchanged and return
-** non-zero.
-**
-** This routine can fail if it is unable to load a collating sequence
-** required for string comparison, or if unable to allocate memory
-** for a UTF conversion required for comparison.  The error is stored
-** in the pParse structure.
-*/
-static int whereEqualScanEst(
-  Parse *pParse,       /* Parsing & code generating context */
-  WhereLoopBuilder *pBuilder,
-  Expr *pExpr,         /* Expression for VALUE in the x=VALUE constraint */
-  tRowcnt *pnRow       /* Write the revised row estimate here */
-){
-  Index *p = pBuilder->pNew->u.btree.pIndex;
-  int nEq = pBuilder->pNew->u.btree.nEq;
-  UnpackedRecord *pRec = pBuilder->pRec;
-  u8 aff;                   /* Column affinity */
-  int rc;                   /* Subfunction return code */
-  tRowcnt a[2];             /* Statistics */
-  int bOk;
-
-  assert( nEq>=1 );
-  assert( nEq<=(p->nColumn+1) );
-  assert( p->aSample!=0 );
-  assert( p->nSample>0 );
-  assert( pBuilder->nRecValid<nEq );
-
-  /* If values are not available for all fields of the index to the left
-  ** of this one, no estimate can be made. Return SQLITE_NOTFOUND. */
-  if( pBuilder->nRecValid<(nEq-1) ){
-    return SQLITE_NOTFOUND;
-  }
-
-  /* This is an optimization only. The call to sqlite3Stat4ProbeSetValue()
-  ** below would return the same value.  */
-  if( nEq>p->nColumn ){
-    *pnRow = 1;
-    return SQLITE_OK;
-  }
-
-  aff = p->pTable->aCol[p->aiColumn[nEq-1]].affinity;
-  rc = sqlite3Stat4ProbeSetValue(pParse, p, &pRec, pExpr, aff, nEq-1, &bOk);
-  pBuilder->pRec = pRec;
-  if( rc!=SQLITE_OK ) return rc;
-  if( bOk==0 ) return SQLITE_NOTFOUND;
-  pBuilder->nRecValid = nEq;
-
-  whereKeyStats(pParse, p, pRec, 0, a);
-  WHERETRACE(0x100,("equality scan regions: %d\n", (int)a[1]));
-  *pnRow = a[1];
-  
-  return rc;
-}
-#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
-
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-/*
-** Estimate the number of rows that will be returned based on
-** an IN constraint where the right-hand side of the IN operator
-** is a list of values.  Example:
-**
-**        WHERE x IN (1,2,3,4)
-**
-** Write the estimated row count into *pnRow and return SQLITE_OK. 
-** If unable to make an estimate, leave *pnRow unchanged and return
-** non-zero.
-**
-** This routine can fail if it is unable to load a collating sequence
-** required for string comparison, or if unable to allocate memory
-** for a UTF conversion required for comparison.  The error is stored
-** in the pParse structure.
-*/
-static int whereInScanEst(
-  Parse *pParse,       /* Parsing & code generating context */
-  WhereLoopBuilder *pBuilder,
-  ExprList *pList,     /* The value list on the RHS of "x IN (v1,v2,v3,...)" */
-  tRowcnt *pnRow       /* Write the revised row estimate here */
-){
-  Index *p = pBuilder->pNew->u.btree.pIndex;
-  int nRecValid = pBuilder->nRecValid;
-  int rc = SQLITE_OK;     /* Subfunction return code */
-  tRowcnt nEst;           /* Number of rows for a single term */
-  tRowcnt nRowEst = 0;    /* New estimate of the number of rows */
-  int i;                  /* Loop counter */
-
-  assert( p->aSample!=0 );
-  for(i=0; rc==SQLITE_OK && i<pList->nExpr; i++){
-    nEst = p->aiRowEst[0];
-    rc = whereEqualScanEst(pParse, pBuilder, pList->a[i].pExpr, &nEst);
-    nRowEst += nEst;
-    pBuilder->nRecValid = nRecValid;
-  }
-
-  if( rc==SQLITE_OK ){
-    if( nRowEst > p->aiRowEst[0] ) nRowEst = p->aiRowEst[0];
-    *pnRow = nRowEst;
-    WHERETRACE(0x100,("IN row estimate: est=%g\n", nRowEst));
-  }
-  assert( pBuilder->nRecValid==nRecValid );
-  return rc;
-}
-#endif /* SQLITE_ENABLE_STAT3_OR_STAT4 */
-
-/*
-** Disable a term in the WHERE clause.  Except, do not disable the term
-** if it controls a LEFT OUTER JOIN and it did not originate in the ON
-** or USING clause of that join.
-**
-** Consider the term t2.z='ok' in the following queries:
-**
-**   (1)  SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x WHERE t2.z='ok'
-**   (2)  SELECT * FROM t1 LEFT JOIN t2 ON t1.a=t2.x AND t2.z='ok'
-**   (3)  SELECT * FROM t1, t2 WHERE t1.a=t2.x AND t2.z='ok'
-**
-** The t2.z='ok' is disabled in the in (2) because it originates
-** in the ON clause.  The term is disabled in (3) because it is not part
-** of a LEFT OUTER JOIN.  In (1), the term is not disabled.
-**
-** Disabling a term causes that term to not be tested in the inner loop
-** of the join.  Disabling is an optimization.  When terms are satisfied
-** by indices, we disable them to prevent redundant tests in the inner
-** loop.  We would get the correct results if nothing were ever disabled,
-** but joins might run a little slower.  The trick is to disable as much
-** as we can without disabling too much.  If we disabled in (1), we'd get
-** the wrong answer.  See ticket #813.
-*/
-static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
-  if( pTerm
-      && (pTerm->wtFlags & TERM_CODED)==0
-      && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_FromJoin))
-      && (pLevel->notReady & pTerm->prereqAll)==0
-  ){
-    pTerm->wtFlags |= TERM_CODED;
-    if( pTerm->iParent>=0 ){
-      WhereTerm *pOther = &pTerm->pWC->a[pTerm->iParent];
-      if( (--pOther->nChild)==0 ){
-        disableTerm(pLevel, pOther);
-      }
-    }
-  }
-}
-
-/*
-** Code an OP_Affinity opcode to apply the column affinity string zAff
-** to the n registers starting at base. 
-**
-** As an optimization, SQLITE_AFF_NONE entries (which are no-ops) at the
-** beginning and end of zAff are ignored.  If all entries in zAff are
-** SQLITE_AFF_NONE, then no code gets generated.
-**
-** This routine makes its own copy of zAff so that the caller is free
-** to modify zAff after this routine returns.
-*/
-static void codeApplyAffinity(Parse *pParse, int base, int n, char *zAff){
-  Vdbe *v = pParse->pVdbe;
-  if( zAff==0 ){
-    assert( pParse->db->mallocFailed );
-    return;
-  }
-  assert( v!=0 );
-
-  /* Adjust base and n to skip over SQLITE_AFF_NONE entries at the beginning
-  ** and end of the affinity string.
-  */
-  while( n>0 && zAff[0]==SQLITE_AFF_NONE ){
-    n--;
-    base++;
-    zAff++;
-  }
-  while( n>1 && zAff[n-1]==SQLITE_AFF_NONE ){
-    n--;
-  }
-
-  /* Code the OP_Affinity opcode if there is anything left to do. */
-  if( n>0 ){
-    sqlite3VdbeAddOp2(v, OP_Affinity, base, n);
-    sqlite3VdbeChangeP4(v, -1, zAff, n);
-    sqlite3ExprCacheAffinityChange(pParse, base, n);
-  }
-}
-
-
-/*
-** Generate code for a single equality term of the WHERE clause.  An equality
-** term can be either X=expr or X IN (...).   pTerm is the term to be 
-** coded.
-**
-** The current value for the constraint is left in register iReg.
-**
-** For a constraint of the form X=expr, the expression is evaluated and its
-** result is left on the stack.  For constraints of the form X IN (...)
-** this routine sets up a loop that will iterate over all values of X.
-*/
-static int codeEqualityTerm(
-  Parse *pParse,      /* The parsing context */
-  WhereTerm *pTerm,   /* The term of the WHERE clause to be coded */
-  WhereLevel *pLevel, /* The level of the FROM clause we are working on */
-  int iEq,            /* Index of the equality term within this level */
-  int bRev,           /* True for reverse-order IN operations */
-  int iTarget         /* Attempt to leave results in this register */
-){
-  Expr *pX = pTerm->pExpr;
-  Vdbe *v = pParse->pVdbe;
-  int iReg;                  /* Register holding results */
-
-  assert( iTarget>0 );
-  if( pX->op==TK_EQ ){
-    iReg = sqlite3ExprCodeTarget(pParse, pX->pRight, iTarget);
-  }else if( pX->op==TK_ISNULL ){
-    iReg = iTarget;
-    sqlite3VdbeAddOp2(v, OP_Null, 0, iReg);
-#ifndef SQLITE_OMIT_SUBQUERY
-  }else{
-    int eType;
-    int iTab;
-    struct InLoop *pIn;
-    WhereLoop *pLoop = pLevel->pWLoop;
-
-    if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0
-      && pLoop->u.btree.pIndex!=0
-      && pLoop->u.btree.pIndex->aSortOrder[iEq]
-    ){
-      testcase( iEq==0 );
-      testcase( bRev );
-      bRev = !bRev;
-    }
-    assert( pX->op==TK_IN );
-    iReg = iTarget;
-    eType = sqlite3FindInIndex(pParse, pX, 0);
-    if( eType==IN_INDEX_INDEX_DESC ){
-      testcase( bRev );
-      bRev = !bRev;
-    }
-    iTab = pX->iTable;
-    sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iTab, 0);
-    assert( (pLoop->wsFlags & WHERE_MULTI_OR)==0 );
-    pLoop->wsFlags |= WHERE_IN_ABLE;
-    if( pLevel->u.in.nIn==0 ){
-      pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
-    }
-    pLevel->u.in.nIn++;
-    pLevel->u.in.aInLoop =
-       sqlite3DbReallocOrFree(pParse->db, pLevel->u.in.aInLoop,
-                              sizeof(pLevel->u.in.aInLoop[0])*pLevel->u.in.nIn);
-    pIn = pLevel->u.in.aInLoop;
-    if( pIn ){
-      pIn += pLevel->u.in.nIn - 1;
-      pIn->iCur = iTab;
-      if( eType==IN_INDEX_ROWID ){
-        pIn->addrInTop = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iReg);
-      }else{
-        pIn->addrInTop = sqlite3VdbeAddOp3(v, OP_Column, iTab, 0, iReg);
-      }
-      pIn->eEndLoopOp = bRev ? OP_Prev : OP_Next;
-      sqlite3VdbeAddOp1(v, OP_IsNull, iReg);
-    }else{
-      pLevel->u.in.nIn = 0;
-    }
-#endif
-  }
-  disableTerm(pLevel, pTerm);
-  return iReg;
-}
-
-/*
-** Generate code that will evaluate all == and IN constraints for an
-** index.
-**
-** For example, consider table t1(a,b,c,d,e,f) with index i1(a,b,c).
-** Suppose the WHERE clause is this:  a==5 AND b IN (1,2,3) AND c>5 AND c<10
-** The index has as many as three equality constraints, but in this
-** example, the third "c" value is an inequality.  So only two 
-** constraints are coded.  This routine will generate code to evaluate
-** a==5 and b IN (1,2,3).  The current values for a and b will be stored
-** in consecutive registers and the index of the first register is returned.
-**
-** In the example above nEq==2.  But this subroutine works for any value
-** of nEq including 0.  If nEq==0, this routine is nearly a no-op.
-** The only thing it does is allocate the pLevel->iMem memory cell and
-** compute the affinity string.
-**
-** This routine always allocates at least one memory cell and returns
-** the index of that memory cell. The code that
-** calls this routine will use that memory cell to store the termination
-** key value of the loop.  If one or more IN operators appear, then
-** this routine allocates an additional nEq memory cells for internal
-** use.
-**
-** Before returning, *pzAff is set to point to a buffer containing a
-** copy of the column affinity string of the index allocated using
-** sqlite3DbMalloc(). Except, entries in the copy of the string associated
-** with equality constraints that use NONE affinity are set to
-** SQLITE_AFF_NONE. This is to deal with SQL such as the following:
-**
-**   CREATE TABLE t1(a TEXT PRIMARY KEY, b);
-**   SELECT ... FROM t1 AS t2, t1 WHERE t1.a = t2.b;
-**
-** In the example above, the index on t1(a) has TEXT affinity. But since
-** the right hand side of the equality constraint (t2.b) has NONE affinity,
-** no conversion should be attempted before using a t2.b value as part of
-** a key to search the index. Hence the first byte in the returned affinity
-** string in this example would be set to SQLITE_AFF_NONE.
-*/
-static int codeAllEqualityTerms(
-  Parse *pParse,        /* Parsing context */
-  WhereLevel *pLevel,   /* Which nested loop of the FROM we are coding */
-  int bRev,             /* Reverse the order of IN operators */
-  int nExtraReg,        /* Number of extra registers to allocate */
-  char **pzAff          /* OUT: Set to point to affinity string */
-){
-  int nEq;                      /* The number of == or IN constraints to code */
-  Vdbe *v = pParse->pVdbe;      /* The vm under construction */
-  Index *pIdx;                  /* The index being used for this loop */
-  WhereTerm *pTerm;             /* A single constraint term */
-  WhereLoop *pLoop;             /* The WhereLoop object */
-  int j;                        /* Loop counter */
-  int regBase;                  /* Base register */
-  int nReg;                     /* Number of registers to allocate */
-  char *zAff;                   /* Affinity string to return */
-
-  /* This module is only called on query plans that use an index. */
-  pLoop = pLevel->pWLoop;
-  assert( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 );
-  nEq = pLoop->u.btree.nEq;
-  pIdx = pLoop->u.btree.pIndex;
-  assert( pIdx!=0 );
-
-  /* Figure out how many memory cells we will need then allocate them.
-  */
-  regBase = pParse->nMem + 1;
-  nReg = pLoop->u.btree.nEq + nExtraReg;
-  pParse->nMem += nReg;
-
-  zAff = sqlite3DbStrDup(pParse->db, sqlite3IndexAffinityStr(v, pIdx));
-  if( !zAff ){
-    pParse->db->mallocFailed = 1;
-  }
-
-  /* Evaluate the equality constraints
-  */
-  assert( zAff==0 || (int)strlen(zAff)>=nEq );
-  for(j=0; j<nEq; j++){
-    int r1;
-    pTerm = pLoop->aLTerm[j];
-    assert( pTerm!=0 );
-    /* The following true for indices with redundant columns. 
-    ** Ex: CREATE INDEX i1 ON t1(a,b,a); SELECT * FROM t1 WHERE a=0 AND b=0; */
-    testcase( (pTerm->wtFlags & TERM_CODED)!=0 );
-    testcase( pTerm->wtFlags & TERM_VIRTUAL );
-    r1 = codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, regBase+j);
-    if( r1!=regBase+j ){
-      if( nReg==1 ){
-        sqlite3ReleaseTempReg(pParse, regBase);
-        regBase = r1;
-      }else{
-        sqlite3VdbeAddOp2(v, OP_SCopy, r1, regBase+j);
-      }
-    }
-    testcase( pTerm->eOperator & WO_ISNULL );
-    testcase( pTerm->eOperator & WO_IN );
-    if( (pTerm->eOperator & (WO_ISNULL|WO_IN))==0 ){
-      Expr *pRight = pTerm->pExpr->pRight;
-      sqlite3ExprCodeIsNullJump(v, pRight, regBase+j, pLevel->addrBrk);
-      if( zAff ){
-        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_NONE ){
-          zAff[j] = SQLITE_AFF_NONE;
-        }
-        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){
-          zAff[j] = SQLITE_AFF_NONE;
-        }
-      }
-    }
-  }
-  *pzAff = zAff;
-  return regBase;
-}
-
-#ifndef SQLITE_OMIT_EXPLAIN
-/*
-** This routine is a helper for explainIndexRange() below
-**
-** pStr holds the text of an expression that we are building up one term
-** at a time.  This routine adds a new term to the end of the expression.
-** Terms are separated by AND so add the "AND" text for second and subsequent
-** terms only.
-*/
-static void explainAppendTerm(
-  StrAccum *pStr,             /* The text expression being built */
-  int iTerm,                  /* Index of this term.  First is zero */
-  const char *zColumn,        /* Name of the column */
-  const char *zOp             /* Name of the operator */
-){
-  if( iTerm ) sqlite3StrAccumAppend(pStr, " AND ", 5);
-  sqlite3StrAccumAppend(pStr, zColumn, -1);
-  sqlite3StrAccumAppend(pStr, zOp, 1);
-  sqlite3StrAccumAppend(pStr, "?", 1);
-}
-
-/*
-** Argument pLevel describes a strategy for scanning table pTab. This 
-** function returns a pointer to a string buffer containing a description
-** of the subset of table rows scanned by the strategy in the form of an
-** SQL expression. Or, if all rows are scanned, NULL is returned.
-**
-** For example, if the query:
-**
-**   SELECT * FROM t1 WHERE a=1 AND b>2;
-**
-** is run and there is an index on (a, b), then this function returns a
-** string similar to:
-**
-**   "a=? AND b>?"
-**
-** The returned pointer points to memory obtained from sqlite3DbMalloc().
-** It is the responsibility of the caller to free the buffer when it is
-** no longer required.
-*/
-static char *explainIndexRange(sqlite3 *db, WhereLoop *pLoop, Table *pTab){
-  Index *pIndex = pLoop->u.btree.pIndex;
-  int nEq = pLoop->u.btree.nEq;
-  int i, j;
-  Column *aCol = pTab->aCol;
-  int *aiColumn = pIndex->aiColumn;
-  StrAccum txt;
-
-  if( nEq==0 && (pLoop->wsFlags & (WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))==0 ){
-    return 0;
-  }
-  sqlite3StrAccumInit(&txt, 0, 0, SQLITE_MAX_LENGTH);
-  txt.db = db;
-  sqlite3StrAccumAppend(&txt, " (", 2);
-  for(i=0; i<nEq; i++){
-    char *z = (i==pIndex->nColumn ) ? "rowid" : aCol[aiColumn[i]].zName;
-    explainAppendTerm(&txt, i, z, "=");
-  }
-
-  j = i;
-  if( pLoop->wsFlags&WHERE_BTM_LIMIT ){
-    char *z = (j==pIndex->nColumn ) ? "rowid" : aCol[aiColumn[j]].zName;
-    explainAppendTerm(&txt, i++, z, ">");
-  }
-  if( pLoop->wsFlags&WHERE_TOP_LIMIT ){
-    char *z = (j==pIndex->nColumn ) ? "rowid" : aCol[aiColumn[j]].zName;
-    explainAppendTerm(&txt, i, z, "<");
-  }
-  sqlite3StrAccumAppend(&txt, ")", 1);
-  return sqlite3StrAccumFinish(&txt);
-}
-
-/*
-** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN
-** command. If the query being compiled is an EXPLAIN QUERY PLAN, a single
-** record is added to the output to describe the table scan strategy in 
-** pLevel.
-*/
-static void explainOneScan(
-  Parse *pParse,                  /* Parse context */
-  SrcList *pTabList,              /* Table list this loop refers to */
-  WhereLevel *pLevel,             /* Scan to write OP_Explain opcode for */
-  int iLevel,                     /* Value for "level" column of output */
-  int iFrom,                      /* Value for "from" column of output */
-  u16 wctrlFlags                  /* Flags passed to sqlite3WhereBegin() */
-){
-  if( pParse->explain==2 ){
-    struct SrcList_item *pItem = &pTabList->a[pLevel->iFrom];
-    Vdbe *v = pParse->pVdbe;      /* VM being constructed */
-    sqlite3 *db = pParse->db;     /* Database handle */
-    char *zMsg;                   /* Text to add to EQP output */
-    int iId = pParse->iSelectId;  /* Select id (left-most output column) */
-    int isSearch;                 /* True for a SEARCH. False for SCAN. */
-    WhereLoop *pLoop;             /* The controlling WhereLoop object */
-    u32 flags;                    /* Flags that describe this loop */
-
-    pLoop = pLevel->pWLoop;
-    flags = pLoop->wsFlags;
-    if( (flags&WHERE_MULTI_OR) || (wctrlFlags&WHERE_ONETABLE_ONLY) ) return;
-
-    isSearch = (flags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0
-            || ((flags&WHERE_VIRTUALTABLE)==0 && (pLoop->u.btree.nEq>0))
-            || (wctrlFlags&(WHERE_ORDERBY_MIN|WHERE_ORDERBY_MAX));
-
-    zMsg = sqlite3MPrintf(db, "%s", isSearch?"SEARCH":"SCAN");
-    if( pItem->pSelect ){
-      zMsg = sqlite3MAppendf(db, zMsg, "%s SUBQUERY %d", zMsg,pItem->iSelectId);
-    }else{
-      zMsg = sqlite3MAppendf(db, zMsg, "%s TABLE %s", zMsg, pItem->zName);
-    }
-
-    if( pItem->zAlias ){
-      zMsg = sqlite3MAppendf(db, zMsg, "%s AS %s", zMsg, pItem->zAlias);
-    }
-    if( (flags & (WHERE_IPK|WHERE_VIRTUALTABLE))==0
-     && ALWAYS(pLoop->u.btree.pIndex!=0)
-    ){
-      char *zWhere = explainIndexRange(db, pLoop, pItem->pTab);
-      zMsg = sqlite3MAppendf(db, zMsg,
-               ((flags & WHERE_AUTO_INDEX) ? 
-                   "%s USING AUTOMATIC %sINDEX%.0s%s" :
-                   "%s USING %sINDEX %s%s"), 
-               zMsg, ((flags & WHERE_IDX_ONLY) ? "COVERING " : ""),
-               pLoop->u.btree.pIndex->zName, zWhere);
-      sqlite3DbFree(db, zWhere);
-    }else if( (flags & WHERE_IPK)!=0 && (flags & WHERE_CONSTRAINT)!=0 ){
-      zMsg = sqlite3MAppendf(db, zMsg, "%s USING INTEGER PRIMARY KEY", zMsg);
-
-      if( flags&(WHERE_COLUMN_EQ|WHERE_COLUMN_IN) ){
-        zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid=?)", zMsg);
-      }else if( (flags&WHERE_BOTH_LIMIT)==WHERE_BOTH_LIMIT ){
-        zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid>? AND rowid<?)", zMsg);
-      }else if( flags&WHERE_BTM_LIMIT ){
-        zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid>?)", zMsg);
-      }else if( ALWAYS(flags&WHERE_TOP_LIMIT) ){
-        zMsg = sqlite3MAppendf(db, zMsg, "%s (rowid<?)", zMsg);
-      }
-    }
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-    else if( (flags & WHERE_VIRTUALTABLE)!=0 ){
-      zMsg = sqlite3MAppendf(db, zMsg, "%s VIRTUAL TABLE INDEX %d:%s", zMsg,
-                  pLoop->u.vtab.idxNum, pLoop->u.vtab.idxStr);
-    }
-#endif
-    zMsg = sqlite3MAppendf(db, zMsg, "%s", zMsg);
-    sqlite3VdbeAddOp4(v, OP_Explain, iId, iLevel, iFrom, zMsg, P4_DYNAMIC);
-  }
-}
-#else
-# define explainOneScan(u,v,w,x,y,z)
-#endif /* SQLITE_OMIT_EXPLAIN */
-
-
-/*
-** Generate code for the start of the iLevel-th loop in the WHERE clause
-** implementation described by pWInfo.
-*/
-static Bitmask codeOneLoopStart(
-  WhereInfo *pWInfo,   /* Complete information about the WHERE clause */
-  int iLevel,          /* Which level of pWInfo->a[] should be coded */
-  Bitmask notReady     /* Which tables are currently available */
-){
-  int j, k;            /* Loop counters */
-  int iCur;            /* The VDBE cursor for the table */
-  int addrNxt;         /* Where to jump to continue with the next IN case */
-  int omitTable;       /* True if we use the index only */
-  int bRev;            /* True if we need to scan in reverse order */
-  WhereLevel *pLevel;  /* The where level to be coded */
-  WhereLoop *pLoop;    /* The WhereLoop object being coded */
-  WhereClause *pWC;    /* Decomposition of the entire WHERE clause */
-  WhereTerm *pTerm;               /* A WHERE clause term */
-  Parse *pParse;                  /* Parsing context */
-  sqlite3 *db;                    /* Database connection */
-  Vdbe *v;                        /* The prepared stmt under constructions */
-  struct SrcList_item *pTabItem;  /* FROM clause term being coded */
-  int addrBrk;                    /* Jump here to break out of the loop */
-  int addrCont;                   /* Jump here to continue with next cycle */
-  int iRowidReg = 0;        /* Rowid is stored in this register, if not zero */
-  int iReleaseReg = 0;      /* Temp register to free before returning */
-
-  pParse = pWInfo->pParse;
-  v = pParse->pVdbe;
-  pWC = &pWInfo->sWC;
-  db = pParse->db;
-  pLevel = &pWInfo->a[iLevel];
-  pLoop = pLevel->pWLoop;
-  pTabItem = &pWInfo->pTabList->a[pLevel->iFrom];
-  iCur = pTabItem->iCursor;
-  pLevel->notReady = notReady & ~getMask(&pWInfo->sMaskSet, iCur);
-  bRev = (pWInfo->revMask>>iLevel)&1;
-  omitTable = (pLoop->wsFlags & WHERE_IDX_ONLY)!=0 
-           && (pWInfo->wctrlFlags & WHERE_FORCE_TABLE)==0;
-  VdbeNoopComment((v, "Begin Join Loop %d", iLevel));
-
-  /* Create labels for the "break" and "continue" instructions
-  ** for the current loop.  Jump to addrBrk to break out of a loop.
-  ** Jump to cont to go immediately to the next iteration of the
-  ** loop.
-  **
-  ** When there is an IN operator, we also have a "addrNxt" label that
-  ** means to continue with the next IN value combination.  When
-  ** there are no IN operators in the constraints, the "addrNxt" label
-  ** is the same as "addrBrk".
-  */
-  addrBrk = pLevel->addrBrk = pLevel->addrNxt = sqlite3VdbeMakeLabel(v);
-  addrCont = pLevel->addrCont = sqlite3VdbeMakeLabel(v);
-
-  /* If this is the right table of a LEFT OUTER JOIN, allocate and
-  ** initialize a memory cell that records if this table matches any
-  ** row of the left table of the join.
-  */
-  if( pLevel->iFrom>0 && (pTabItem[0].jointype & JT_LEFT)!=0 ){
-    pLevel->iLeftJoin = ++pParse->nMem;
-    sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin);
-    VdbeComment((v, "init LEFT JOIN no-match flag"));
-  }
-
-  /* Special case of a FROM clause subquery implemented as a co-routine */
-  if( pTabItem->viaCoroutine ){
-    int regYield = pTabItem->regReturn;
-    sqlite3VdbeAddOp2(v, OP_Integer, pTabItem->addrFillSub-1, regYield);
-    pLevel->p2 =  sqlite3VdbeAddOp1(v, OP_Yield, regYield);
-    VdbeComment((v, "next row of co-routine %s", pTabItem->pTab->zName));
-    sqlite3VdbeAddOp2(v, OP_If, regYield+1, addrBrk);
-    pLevel->op = OP_Goto;
-  }else
-
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-  if(  (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){
-    /* Case 1:  The table is a virtual-table.  Use the VFilter and VNext
-    **          to access the data.
-    */
-    int iReg;   /* P3 Value for OP_VFilter */
-    int addrNotFound;
-    int nConstraint = pLoop->nLTerm;
-
-    sqlite3ExprCachePush(pParse);
-    iReg = sqlite3GetTempRange(pParse, nConstraint+2);
-    addrNotFound = pLevel->addrBrk;
-    for(j=0; j<nConstraint; j++){
-      int iTarget = iReg+j+2;
-      pTerm = pLoop->aLTerm[j];
-      if( pTerm==0 ) continue;
-      if( pTerm->eOperator & WO_IN ){
-        codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, iTarget);
-        addrNotFound = pLevel->addrNxt;
-      }else{
-        sqlite3ExprCode(pParse, pTerm->pExpr->pRight, iTarget);
-      }
-    }
-    sqlite3VdbeAddOp2(v, OP_Integer, pLoop->u.vtab.idxNum, iReg);
-    sqlite3VdbeAddOp2(v, OP_Integer, nConstraint, iReg+1);
-    sqlite3VdbeAddOp4(v, OP_VFilter, iCur, addrNotFound, iReg,
-                      pLoop->u.vtab.idxStr,
-                      pLoop->u.vtab.needFree ? P4_MPRINTF : P4_STATIC);
-    pLoop->u.vtab.needFree = 0;
-    for(j=0; j<nConstraint && j<16; j++){
-      if( (pLoop->u.vtab.omitMask>>j)&1 ){
-        disableTerm(pLevel, pLoop->aLTerm[j]);
-      }
-    }
-    pLevel->op = OP_VNext;
-    pLevel->p1 = iCur;
-    pLevel->p2 = sqlite3VdbeCurrentAddr(v);
-    sqlite3ReleaseTempRange(pParse, iReg, nConstraint+2);
-    sqlite3ExprCachePop(pParse, 1);
-  }else
-#endif /* SQLITE_OMIT_VIRTUALTABLE */
-
-  if( (pLoop->wsFlags & WHERE_IPK)!=0
-   && (pLoop->wsFlags & (WHERE_COLUMN_IN|WHERE_COLUMN_EQ))!=0
-  ){
-    /* Case 2:  We can directly reference a single row using an
-    **          equality comparison against the ROWID field.  Or
-    **          we reference multiple rows using a "rowid IN (...)"
-    **          construct.
-    */
-    assert( pLoop->u.btree.nEq==1 );
-    iReleaseReg = sqlite3GetTempReg(pParse);
-    pTerm = pLoop->aLTerm[0];
-    assert( pTerm!=0 );
-    assert( pTerm->pExpr!=0 );
-    assert( omitTable==0 );
-    testcase( pTerm->wtFlags & TERM_VIRTUAL );
-    iRowidReg = codeEqualityTerm(pParse, pTerm, pLevel, 0, bRev, iReleaseReg);
-    addrNxt = pLevel->addrNxt;
-    sqlite3VdbeAddOp2(v, OP_MustBeInt, iRowidReg, addrNxt);
-    sqlite3VdbeAddOp3(v, OP_NotExists, iCur, addrNxt, iRowidReg);
-    sqlite3ExprCacheAffinityChange(pParse, iRowidReg, 1);
-    sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
-    VdbeComment((v, "pk"));
-    pLevel->op = OP_Noop;
-  }else if( (pLoop->wsFlags & WHERE_IPK)!=0
-         && (pLoop->wsFlags & WHERE_COLUMN_RANGE)!=0
-  ){
-    /* Case 3:  We have an inequality comparison against the ROWID field.
-    */
-    int testOp = OP_Noop;
-    int start;
-    int memEndValue = 0;
-    WhereTerm *pStart, *pEnd;
-
-    assert( omitTable==0 );
-    j = 0;
-    pStart = pEnd = 0;
-    if( pLoop->wsFlags & WHERE_BTM_LIMIT ) pStart = pLoop->aLTerm[j++];
-    if( pLoop->wsFlags & WHERE_TOP_LIMIT ) pEnd = pLoop->aLTerm[j++];
-    assert( pStart!=0 || pEnd!=0 );
-    if( bRev ){
-      pTerm = pStart;
-      pStart = pEnd;
-      pEnd = pTerm;
-    }
-    if( pStart ){
-      Expr *pX;             /* The expression that defines the start bound */
-      int r1, rTemp;        /* Registers for holding the start boundary */
-
-      /* The following constant maps TK_xx codes into corresponding 
-      ** seek opcodes.  It depends on a particular ordering of TK_xx
-      */
-      const u8 aMoveOp[] = {
-           /* TK_GT */  OP_SeekGt,
-           /* TK_LE */  OP_SeekLe,
-           /* TK_LT */  OP_SeekLt,
-           /* TK_GE */  OP_SeekGe
-      };
-      assert( TK_LE==TK_GT+1 );      /* Make sure the ordering.. */
-      assert( TK_LT==TK_GT+2 );      /*  ... of the TK_xx values... */
-      assert( TK_GE==TK_GT+3 );      /*  ... is correcct. */
-
-      assert( (pStart->wtFlags & TERM_VNULL)==0 );
-      testcase( pStart->wtFlags & TERM_VIRTUAL );
-      pX = pStart->pExpr;
-      assert( pX!=0 );
-      testcase( pStart->leftCursor!=iCur ); /* transitive constraints */
-      r1 = sqlite3ExprCodeTemp(pParse, pX->pRight, &rTemp);
-      sqlite3VdbeAddOp3(v, aMoveOp[pX->op-TK_GT], iCur, addrBrk, r1);
-      VdbeComment((v, "pk"));
-      sqlite3ExprCacheAffinityChange(pParse, r1, 1);
-      sqlite3ReleaseTempReg(pParse, rTemp);
-      disableTerm(pLevel, pStart);
-    }else{
-      sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, addrBrk);
-    }
-    if( pEnd ){
-      Expr *pX;
-      pX = pEnd->pExpr;
-      assert( pX!=0 );
-      assert( (pEnd->wtFlags & TERM_VNULL)==0 );
-      testcase( pEnd->leftCursor!=iCur ); /* Transitive constraints */
-      testcase( pEnd->wtFlags & TERM_VIRTUAL );
-      memEndValue = ++pParse->nMem;
-      sqlite3ExprCode(pParse, pX->pRight, memEndValue);
-      if( pX->op==TK_LT || pX->op==TK_GT ){
-        testOp = bRev ? OP_Le : OP_Ge;
-      }else{
-        testOp = bRev ? OP_Lt : OP_Gt;
-      }
-      disableTerm(pLevel, pEnd);
-    }
-    start = sqlite3VdbeCurrentAddr(v);
-    pLevel->op = bRev ? OP_Prev : OP_Next;
-    pLevel->p1 = iCur;
-    pLevel->p2 = start;
-    assert( pLevel->p5==0 );
-    if( testOp!=OP_Noop ){
-      iRowidReg = iReleaseReg = sqlite3GetTempReg(pParse);
-      sqlite3VdbeAddOp2(v, OP_Rowid, iCur, iRowidReg);
-      sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
-      sqlite3VdbeAddOp3(v, testOp, memEndValue, addrBrk, iRowidReg);
-      sqlite3VdbeChangeP5(v, SQLITE_AFF_NUMERIC | SQLITE_JUMPIFNULL);
-    }
-  }else if( pLoop->wsFlags & WHERE_INDEXED ){
-    /* Case 4: A scan using an index.
-    **
-    **         The WHERE clause may contain zero or more equality 
-    **         terms ("==" or "IN" operators) that refer to the N
-    **         left-most columns of the index. It may also contain
-    **         inequality constraints (>, <, >= or <=) on the indexed
-    **         column that immediately follows the N equalities. Only 
-    **         the right-most column can be an inequality - the rest must
-    **         use the "==" and "IN" operators. For example, if the 
-    **         index is on (x,y,z), then the following clauses are all 
-    **         optimized:
-    **
-    **            x=5
-    **            x=5 AND y=10
-    **            x=5 AND y<10
-    **            x=5 AND y>5 AND y<10
-    **            x=5 AND y=5 AND z<=10
-    **
-    **         The z<10 term of the following cannot be used, only
-    **         the x=5 term:
-    **
-    **            x=5 AND z<10
-    **
-    **         N may be zero if there are inequality constraints.
-    **         If there are no inequality constraints, then N is at
-    **         least one.
-    **
-    **         This case is also used when there are no WHERE clause
-    **         constraints but an index is selected anyway, in order
-    **         to force the output order to conform to an ORDER BY.
-    */  
-    static const u8 aStartOp[] = {
-      0,
-      0,
-      OP_Rewind,           /* 2: (!start_constraints && startEq &&  !bRev) */
-      OP_Last,             /* 3: (!start_constraints && startEq &&   bRev) */
-      OP_SeekGt,           /* 4: (start_constraints  && !startEq && !bRev) */
-      OP_SeekLt,           /* 5: (start_constraints  && !startEq &&  bRev) */
-      OP_SeekGe,           /* 6: (start_constraints  &&  startEq && !bRev) */
-      OP_SeekLe            /* 7: (start_constraints  &&  startEq &&  bRev) */
-    };
-    static const u8 aEndOp[] = {
-      OP_Noop,             /* 0: (!end_constraints) */
-      OP_IdxGE,            /* 1: (end_constraints && !bRev) */
-      OP_IdxLT             /* 2: (end_constraints && bRev) */
-    };
-    int nEq = pLoop->u.btree.nEq;  /* Number of == or IN terms */
-    int isMinQuery = 0;            /* If this is an optimized SELECT min(x).. */
-    int regBase;                 /* Base register holding constraint values */
-    int r1;                      /* Temp register */
-    WhereTerm *pRangeStart = 0;  /* Inequality constraint at range start */
-    WhereTerm *pRangeEnd = 0;    /* Inequality constraint at range end */
-    int startEq;                 /* True if range start uses ==, >= or <= */
-    int endEq;                   /* True if range end uses ==, >= or <= */
-    int start_constraints;       /* Start of range is constrained */
-    int nConstraint;             /* Number of constraint terms */
-    Index *pIdx;                 /* The index we will be using */
-    int iIdxCur;                 /* The VDBE cursor for the index */
-    int nExtraReg = 0;           /* Number of extra registers needed */
-    int op;                      /* Instruction opcode */
-    char *zStartAff;             /* Affinity for start of range constraint */
-    char *zEndAff;               /* Affinity for end of range constraint */
-
-    pIdx = pLoop->u.btree.pIndex;
-    iIdxCur = pLevel->iIdxCur;
-
-    /* If this loop satisfies a sort order (pOrderBy) request that 
-    ** was passed to this function to implement a "SELECT min(x) ..." 
-    ** query, then the caller will only allow the loop to run for
-    ** a single iteration. This means that the first row returned
-    ** should not have a NULL value stored in 'x'. If column 'x' is
-    ** the first one after the nEq equality constraints in the index,
-    ** this requires some special handling.
-    */
-    if( (pWInfo->wctrlFlags&WHERE_ORDERBY_MIN)!=0
-     && (pWInfo->bOBSat!=0)
-     && (pIdx->nColumn>nEq)
-    ){
-      /* assert( pOrderBy->nExpr==1 ); */
-      /* assert( pOrderBy->a[0].pExpr->iColumn==pIdx->aiColumn[nEq] ); */
-      isMinQuery = 1;
-      nExtraReg = 1;
-    }
-
-    /* Find any inequality constraint terms for the start and end 
-    ** of the range. 
-    */
-    j = nEq;
-    if( pLoop->wsFlags & WHERE_BTM_LIMIT ){
-      pRangeStart = pLoop->aLTerm[j++];
-      nExtraReg = 1;
-    }
-    if( pLoop->wsFlags & WHERE_TOP_LIMIT ){
-      pRangeEnd = pLoop->aLTerm[j++];
-      nExtraReg = 1;
-    }
-
-    /* Generate code to evaluate all constraint terms using == or IN
-    ** and store the values of those terms in an array of registers
-    ** starting at regBase.
-    */
-    regBase = codeAllEqualityTerms(pParse,pLevel,bRev,nExtraReg,&zStartAff);
-    zEndAff = sqlite3DbStrDup(db, zStartAff);
-    addrNxt = pLevel->addrNxt;
-
-    /* If we are doing a reverse order scan on an ascending index, or
-    ** a forward order scan on a descending index, interchange the 
-    ** start and end terms (pRangeStart and pRangeEnd).
-    */
-    if( (nEq<pIdx->nColumn && bRev==(pIdx->aSortOrder[nEq]==SQLITE_SO_ASC))
-     || (bRev && pIdx->nColumn==nEq)
-    ){
-      SWAP(WhereTerm *, pRangeEnd, pRangeStart);
-    }
-
-    testcase( pRangeStart && (pRangeStart->eOperator & WO_LE)!=0 );
-    testcase( pRangeStart && (pRangeStart->eOperator & WO_GE)!=0 );
-    testcase( pRangeEnd && (pRangeEnd->eOperator & WO_LE)!=0 );
-    testcase( pRangeEnd && (pRangeEnd->eOperator & WO_GE)!=0 );
-    startEq = !pRangeStart || pRangeStart->eOperator & (WO_LE|WO_GE);
-    endEq =   !pRangeEnd || pRangeEnd->eOperator & (WO_LE|WO_GE);
-    start_constraints = pRangeStart || nEq>0;
-
-    /* Seek the index cursor to the start of the range. */
-    nConstraint = nEq;
-    if( pRangeStart ){
-      Expr *pRight = pRangeStart->pExpr->pRight;
-      sqlite3ExprCode(pParse, pRight, regBase+nEq);
-      if( (pRangeStart->wtFlags & TERM_VNULL)==0 ){
-        sqlite3ExprCodeIsNullJump(v, pRight, regBase+nEq, addrNxt);
-      }
-      if( zStartAff ){
-        if( sqlite3CompareAffinity(pRight, zStartAff[nEq])==SQLITE_AFF_NONE){
-          /* Since the comparison is to be performed with no conversions
-          ** applied to the operands, set the affinity to apply to pRight to 
-          ** SQLITE_AFF_NONE.  */
-          zStartAff[nEq] = SQLITE_AFF_NONE;
-        }
-        if( sqlite3ExprNeedsNoAffinityChange(pRight, zStartAff[nEq]) ){
-          zStartAff[nEq] = SQLITE_AFF_NONE;
-        }
-      }  
-      nConstraint++;
-      testcase( pRangeStart->wtFlags & TERM_VIRTUAL );
-    }else if( isMinQuery ){
-      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
-      nConstraint++;
-      startEq = 0;
-      start_constraints = 1;
-    }
-    codeApplyAffinity(pParse, regBase, nConstraint, zStartAff);
-    op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
-    assert( op!=0 );
-    testcase( op==OP_Rewind );
-    testcase( op==OP_Last );
-    testcase( op==OP_SeekGt );
-    testcase( op==OP_SeekGe );
-    testcase( op==OP_SeekLe );
-    testcase( op==OP_SeekLt );
-    sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
-
-    /* Load the value for the inequality constraint at the end of the
-    ** range (if any).
-    */
-    nConstraint = nEq;
-    if( pRangeEnd ){
-      Expr *pRight = pRangeEnd->pExpr->pRight;
-      sqlite3ExprCacheRemove(pParse, regBase+nEq, 1);
-      sqlite3ExprCode(pParse, pRight, regBase+nEq);
-      if( (pRangeEnd->wtFlags & TERM_VNULL)==0 ){
-        sqlite3ExprCodeIsNullJump(v, pRight, regBase+nEq, addrNxt);
-      }
-      if( zEndAff ){
-        if( sqlite3CompareAffinity(pRight, zEndAff[nEq])==SQLITE_AFF_NONE){
-          /* Since the comparison is to be performed with no conversions
-          ** applied to the operands, set the affinity to apply to pRight to 
-          ** SQLITE_AFF_NONE.  */
-          zEndAff[nEq] = SQLITE_AFF_NONE;
-        }
-        if( sqlite3ExprNeedsNoAffinityChange(pRight, zEndAff[nEq]) ){
-          zEndAff[nEq] = SQLITE_AFF_NONE;
-        }
-      }  
-      codeApplyAffinity(pParse, regBase, nEq+1, zEndAff);
-      nConstraint++;
-      testcase( pRangeEnd->wtFlags & TERM_VIRTUAL );
-    }
-    sqlite3DbFree(db, zStartAff);
-    sqlite3DbFree(db, zEndAff);
-
-    /* Top of the loop body */
-    pLevel->p2 = sqlite3VdbeCurrentAddr(v);
-
-    /* Check if the index cursor is past the end of the range. */
-    op = aEndOp[(pRangeEnd || nEq) * (1 + bRev)];
-    testcase( op==OP_Noop );
-    testcase( op==OP_IdxGE );
-    testcase( op==OP_IdxLT );
-    if( op!=OP_Noop ){
-      sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
-      sqlite3VdbeChangeP5(v, endEq!=bRev ?1:0);
-    }
-
-    /* If there are inequality constraints, check that the value
-    ** of the table column that the inequality contrains is not NULL.
-    ** If it is, jump to the next iteration of the loop.
-    */
-    r1 = sqlite3GetTempReg(pParse);
-    testcase( pLoop->wsFlags & WHERE_BTM_LIMIT );
-    testcase( pLoop->wsFlags & WHERE_TOP_LIMIT );
-    if( (pLoop->wsFlags & (WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))!=0 ){
-      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, nEq, r1);
-      sqlite3VdbeAddOp2(v, OP_IsNull, r1, addrCont);
-    }
-    sqlite3ReleaseTempReg(pParse, r1);
-
-    /* Seek the table cursor, if required */
-    disableTerm(pLevel, pRangeStart);
-    disableTerm(pLevel, pRangeEnd);
-    if( !omitTable ){
-      iRowidReg = iReleaseReg = sqlite3GetTempReg(pParse);
-      sqlite3VdbeAddOp2(v, OP_IdxRowid, iIdxCur, iRowidReg);
-      sqlite3ExprCacheStore(pParse, iCur, -1, iRowidReg);
-      sqlite3VdbeAddOp2(v, OP_Seek, iCur, iRowidReg);  /* Deferred seek */
-    }
-
-    /* Record the instruction used to terminate the loop. Disable 
-    ** WHERE clause terms made redundant by the index range scan.
-    */
-    if( pLoop->wsFlags & WHERE_ONEROW ){
-      pLevel->op = OP_Noop;
-    }else if( bRev ){
-      pLevel->op = OP_Prev;
-    }else{
-      pLevel->op = OP_Next;
-    }
-    pLevel->p1 = iIdxCur;
-    if( (pLoop->wsFlags & WHERE_CONSTRAINT)==0 ){
-      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
-    }else{
-      assert( pLevel->p5==0 );
-    }
-  }else
-
-#ifndef SQLITE_OMIT_OR_OPTIMIZATION
-  if( pLoop->wsFlags & WHERE_MULTI_OR ){
-    /* Case 5:  Two or more separately indexed terms connected by OR
-    **
-    ** Example:
-    **
-    **   CREATE TABLE t1(a,b,c,d);
-    **   CREATE INDEX i1 ON t1(a);
-    **   CREATE INDEX i2 ON t1(b);
-    **   CREATE INDEX i3 ON t1(c);
-    **
-    **   SELECT * FROM t1 WHERE a=5 OR b=7 OR (c=11 AND d=13)
-    **
-    ** In the example, there are three indexed terms connected by OR.
-    ** The top of the loop looks like this:
-    **
-    **          Null       1                # Zero the rowset in reg 1
-    **
-    ** Then, for each indexed term, the following. The arguments to
-    ** RowSetTest are such that the rowid of the current row is inserted
-    ** into the RowSet. If it is already present, control skips the
-    ** Gosub opcode and jumps straight to the code generated by WhereEnd().
-    **
-    **        sqlite3WhereBegin(<term>)
-    **          RowSetTest                  # Insert rowid into rowset
-    **          Gosub      2 A
-    **        sqlite3WhereEnd()
-    **
-    ** Following the above, code to terminate the loop. Label A, the target
-    ** of the Gosub above, jumps to the instruction right after the Goto.
-    **
-    **          Null       1                # Zero the rowset in reg 1
-    **          Goto       B                # The loop is finished.
-    **
-    **       A: <loop body>                 # Return data, whatever.
-    **
-    **          Return     2                # Jump back to the Gosub
-    **
-    **       B: <after the loop>
-    **
-    */
-    WhereClause *pOrWc;    /* The OR-clause broken out into subterms */
-    SrcList *pOrTab;       /* Shortened table list or OR-clause generation */
-    Index *pCov = 0;             /* Potential covering index (or NULL) */
-    int iCovCur = pParse->nTab++;  /* Cursor used for index scans (if any) */
-
-    int regReturn = ++pParse->nMem;           /* Register used with OP_Gosub */
-    int regRowset = 0;                        /* Register for RowSet object */
-    int regRowid = 0;                         /* Register holding rowid */
-    int iLoopBody = sqlite3VdbeMakeLabel(v);  /* Start of loop body */
-    int iRetInit;                             /* Address of regReturn init */
-    int untestedTerms = 0;             /* Some terms not completely tested */
-    int ii;                            /* Loop counter */
-    Expr *pAndExpr = 0;                /* An ".. AND (...)" expression */
-   
-    pTerm = pLoop->aLTerm[0];
-    assert( pTerm!=0 );
-    assert( pTerm->eOperator & WO_OR );
-    assert( (pTerm->wtFlags & TERM_ORINFO)!=0 );
-    pOrWc = &pTerm->u.pOrInfo->wc;
-    pLevel->op = OP_Return;
-    pLevel->p1 = regReturn;
-
-    /* Set up a new SrcList in pOrTab containing the table being scanned
-    ** by this loop in the a[0] slot and all notReady tables in a[1..] slots.
-    ** This becomes the SrcList in the recursive call to sqlite3WhereBegin().
-    */
-    if( pWInfo->nLevel>1 ){
-      int nNotReady;                 /* The number of notReady tables */
-      struct SrcList_item *origSrc;     /* Original list of tables */
-      nNotReady = pWInfo->nLevel - iLevel - 1;
-      pOrTab = sqlite3StackAllocRaw(db,
-                            sizeof(*pOrTab)+ nNotReady*sizeof(pOrTab->a[0]));
-      if( pOrTab==0 ) return notReady;
-      pOrTab->nAlloc = (u8)(nNotReady + 1);
-      pOrTab->nSrc = pOrTab->nAlloc;
-      memcpy(pOrTab->a, pTabItem, sizeof(*pTabItem));
-      origSrc = pWInfo->pTabList->a;
-      for(k=1; k<=nNotReady; k++){
-        memcpy(&pOrTab->a[k], &origSrc[pLevel[k].iFrom], sizeof(pOrTab->a[k]));
-      }
-    }else{
-      pOrTab = pWInfo->pTabList;
-    }
-
-    /* Initialize the rowset register to contain NULL. An SQL NULL is 
-    ** equivalent to an empty rowset.
-    **
-    ** Also initialize regReturn to contain the address of the instruction 
-    ** immediately following the OP_Return at the bottom of the loop. This
-    ** is required in a few obscure LEFT JOIN cases where control jumps
-    ** over the top of the loop into the body of it. In this case the 
-    ** correct response for the end-of-loop code (the OP_Return) is to 
-    ** fall through to the next instruction, just as an OP_Next does if
-    ** called on an uninitialized cursor.
-    */
-    if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
-      regRowset = ++pParse->nMem;
-      regRowid = ++pParse->nMem;
-      sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset);
-    }
-    iRetInit = sqlite3VdbeAddOp2(v, OP_Integer, 0, regReturn);
-
-    /* If the original WHERE clause is z of the form:  (x1 OR x2 OR ...) AND y
-    ** Then for every term xN, evaluate as the subexpression: xN AND z
-    ** That way, terms in y that are factored into the disjunction will
-    ** be picked up by the recursive calls to sqlite3WhereBegin() below.
-    **
-    ** Actually, each subexpression is converted to "xN AND w" where w is
-    ** the "interesting" terms of z - terms that did not originate in the
-    ** ON or USING clause of a LEFT JOIN, and terms that are usable as 
-    ** indices.
-    **
-    ** This optimization also only applies if the (x1 OR x2 OR ...) term
-    ** is not contained in the ON clause of a LEFT JOIN.
-    ** See ticket http://www.sqlite.org/src/info/f2369304e4
-    */
-    if( pWC->nTerm>1 ){
-      int iTerm;
-      for(iTerm=0; iTerm<pWC->nTerm; iTerm++){
-        Expr *pExpr = pWC->a[iTerm].pExpr;
-        if( &pWC->a[iTerm] == pTerm ) continue;
-        if( ExprHasProperty(pExpr, EP_FromJoin) ) continue;
-        if( pWC->a[iTerm].wtFlags & (TERM_ORINFO) ) continue;
-        if( (pWC->a[iTerm].eOperator & WO_ALL)==0 ) continue;
-        pExpr = sqlite3ExprDup(db, pExpr, 0);
-        pAndExpr = sqlite3ExprAnd(db, pAndExpr, pExpr);
-      }
-      if( pAndExpr ){
-        pAndExpr = sqlite3PExpr(pParse, TK_AND, 0, pAndExpr, 0);
-      }
-    }
-
-    for(ii=0; ii<pOrWc->nTerm; ii++){
-      WhereTerm *pOrTerm = &pOrWc->a[ii];
-      if( pOrTerm->leftCursor==iCur || (pOrTerm->eOperator & WO_AND)!=0 ){
-        WhereInfo *pSubWInfo;          /* Info for single OR-term scan */
-        Expr *pOrExpr = pOrTerm->pExpr;
-        if( pAndExpr && !ExprHasProperty(pOrExpr, EP_FromJoin) ){
-          pAndExpr->pLeft = pOrExpr;
-          pOrExpr = pAndExpr;
-        }
-        /* Loop through table entries that match term pOrTerm. */
-        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0,
-                        WHERE_OMIT_OPEN_CLOSE | WHERE_AND_ONLY |
-                        WHERE_FORCE_TABLE | WHERE_ONETABLE_ONLY, iCovCur);
-        assert( pSubWInfo || pParse->nErr || db->mallocFailed );
-        if( pSubWInfo ){
-          WhereLoop *pSubLoop;
-          explainOneScan(
-              pParse, pOrTab, &pSubWInfo->a[0], iLevel, pLevel->iFrom, 0
-          );
-          if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
-            int iSet = ((ii==pOrWc->nTerm-1)?-1:ii);
-            int r;
-            r = sqlite3ExprCodeGetColumn(pParse, pTabItem->pTab, -1, iCur, 
-                                         regRowid, 0);
-            sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset,
-                                 sqlite3VdbeCurrentAddr(v)+2, r, iSet);
-          }
-          sqlite3VdbeAddOp2(v, OP_Gosub, regReturn, iLoopBody);
-
-          /* The pSubWInfo->untestedTerms flag means that this OR term
-          ** contained one or more AND term from a notReady table.  The
-          ** terms from the notReady table could not be tested and will
-          ** need to be tested later.
-          */
-          if( pSubWInfo->untestedTerms ) untestedTerms = 1;
-
-          /* If all of the OR-connected terms are optimized using the same
-          ** index, and the index is opened using the same cursor number
-          ** by each call to sqlite3WhereBegin() made by this loop, it may
-          ** be possible to use that index as a covering index.
-          **
-          ** If the call to sqlite3WhereBegin() above resulted in a scan that
-          ** uses an index, and this is either the first OR-connected term
-          ** processed or the index is the same as that used by all previous
-          ** terms, set pCov to the candidate covering index. Otherwise, set 
-          ** pCov to NULL to indicate that no candidate covering index will 
-          ** be available.
-          */
-          pSubLoop = pSubWInfo->a[0].pWLoop;
-          assert( (pSubLoop->wsFlags & WHERE_AUTO_INDEX)==0 );
-          if( (pSubLoop->wsFlags & WHERE_INDEXED)!=0
-           && (ii==0 || pSubLoop->u.btree.pIndex==pCov)
-          ){
-            assert( pSubWInfo->a[0].iIdxCur==iCovCur );
-            pCov = pSubLoop->u.btree.pIndex;
-          }else{
-            pCov = 0;
-          }
-
-          /* Finish the loop through table entries that match term pOrTerm. */
-          sqlite3WhereEnd(pSubWInfo);
-        }
-      }
-    }
-    pLevel->u.pCovidx = pCov;
-    if( pCov ) pLevel->iIdxCur = iCovCur;
-    if( pAndExpr ){
-      pAndExpr->pLeft = 0;
-      sqlite3ExprDelete(db, pAndExpr);
-    }
-    sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v));
-    sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrBrk);
-    sqlite3VdbeResolveLabel(v, iLoopBody);
-
-    if( pWInfo->nLevel>1 ) sqlite3StackFree(db, pOrTab);
-    if( !untestedTerms ) disableTerm(pLevel, pTerm);
-  }else
-#endif /* SQLITE_OMIT_OR_OPTIMIZATION */
-
-  {
-    /* Case 6:  There is no usable index.  We must do a complete
-    **          scan of the entire table.
-    */
-    static const u8 aStep[] = { OP_Next, OP_Prev };
-    static const u8 aStart[] = { OP_Rewind, OP_Last };
-    assert( bRev==0 || bRev==1 );
-    pLevel->op = aStep[bRev];
-    pLevel->p1 = iCur;
-    pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrBrk);
-    pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
-  }
-
-  /* Insert code to test every subexpression that can be completely
-  ** computed using the current set of tables.
-  */
-  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
-    Expr *pE;
-    testcase( pTerm->wtFlags & TERM_VIRTUAL );
-    testcase( pTerm->wtFlags & TERM_CODED );
-    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
-    if( (pTerm->prereqAll & pLevel->notReady)!=0 ){
-      testcase( pWInfo->untestedTerms==0
-               && (pWInfo->wctrlFlags & WHERE_ONETABLE_ONLY)!=0 );
-      pWInfo->untestedTerms = 1;
-      continue;
-    }
-    pE = pTerm->pExpr;
-    assert( pE!=0 );
-    if( pLevel->iLeftJoin && !ExprHasProperty(pE, EP_FromJoin) ){
-      continue;
-    }
-    sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL);
-    pTerm->wtFlags |= TERM_CODED;
-  }
-
-  /* Insert code to test for implied constraints based on transitivity
-  ** of the "==" operator.
-  **
-  ** Example: If the WHERE clause contains "t1.a=t2.b" and "t2.b=123"
-  ** and we are coding the t1 loop and the t2 loop has not yet coded,
-  ** then we cannot use the "t1.a=t2.b" constraint, but we can code
-  ** the implied "t1.a=123" constraint.
-  */
-  for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
-    Expr *pE, *pEAlt;
-    WhereTerm *pAlt;
-    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
-    if( pTerm->eOperator!=(WO_EQUIV|WO_EQ) ) continue;
-    if( pTerm->leftCursor!=iCur ) continue;
-    if( pLevel->iLeftJoin ) continue;
-    pE = pTerm->pExpr;
-    assert( !ExprHasProperty(pE, EP_FromJoin) );
-    assert( (pTerm->prereqRight & pLevel->notReady)!=0 );
-    pAlt = findTerm(pWC, iCur, pTerm->u.leftColumn, notReady, WO_EQ|WO_IN, 0);
-    if( pAlt==0 ) continue;
-    if( pAlt->wtFlags & (TERM_CODED) ) continue;
-    testcase( pAlt->eOperator & WO_EQ );
-    testcase( pAlt->eOperator & WO_IN );
-    VdbeNoopComment((v, "begin transitive constraint"));
-    pEAlt = sqlite3StackAllocRaw(db, sizeof(*pEAlt));
-    if( pEAlt ){
-      *pEAlt = *pAlt->pExpr;
-      pEAlt->pLeft = pE->pLeft;
-      sqlite3ExprIfFalse(pParse, pEAlt, addrCont, SQLITE_JUMPIFNULL);
-      sqlite3StackFree(db, pEAlt);
-    }
-  }
-
-  /* For a LEFT OUTER JOIN, generate code that will record the fact that
-  ** at least one row of the right table has matched the left table.  
-  */
-  if( pLevel->iLeftJoin ){
-    pLevel->addrFirst = sqlite3VdbeCurrentAddr(v);
-    sqlite3VdbeAddOp2(v, OP_Integer, 1, pLevel->iLeftJoin);
-    VdbeComment((v, "record LEFT JOIN hit"));
-    sqlite3ExprCacheClear(pParse);
-    for(pTerm=pWC->a, j=0; j<pWC->nTerm; j++, pTerm++){
-      testcase( pTerm->wtFlags & TERM_VIRTUAL );
-      testcase( pTerm->wtFlags & TERM_CODED );
-      if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
-      if( (pTerm->prereqAll & pLevel->notReady)!=0 ){
-        assert( pWInfo->untestedTerms );
-        continue;
-      }
-      assert( pTerm->pExpr );
-      sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL);
-      pTerm->wtFlags |= TERM_CODED;
-    }
-  }
-  sqlite3ReleaseTempReg(pParse, iReleaseReg);
-
-  return pLevel->notReady;
-}
-
-#ifdef WHERETRACE_ENABLED
-/*
-** Print a WhereLoop object for debugging purposes
-*/
-static void whereLoopPrint(WhereLoop *p, SrcList *pTabList){
-  int nb = 1+(pTabList->nSrc+7)/8;
-  struct SrcList_item *pItem = pTabList->a + p->iTab;
-  Table *pTab = pItem->pTab;
-  sqlite3DebugPrintf("%c%2d.%0*llx.%0*llx", p->cId,
-                     p->iTab, nb, p->maskSelf, nb, p->prereq);
-  sqlite3DebugPrintf(" %12s",
-                     pItem->zAlias ? pItem->zAlias : pTab->zName);
-  if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){
-    if( p->u.btree.pIndex ){
-      const char *zName = p->u.btree.pIndex->zName;
-      if( zName==0 ) zName = "ipk";
-      if( strncmp(zName, "sqlite_autoindex_", 17)==0 ){
-        int i = sqlite3Strlen30(zName) - 1;
-        while( zName[i]!='_' ) i--;
-        zName += i;
-      }
-      sqlite3DebugPrintf(".%-16s %2d", zName, p->u.btree.nEq);
-    }else{
-      sqlite3DebugPrintf("%20s","");
-    }
-  }else{
-    char *z;
-    if( p->u.vtab.idxStr ){
-      z = sqlite3_mprintf("(%d,\"%s\",%x)",
-                p->u.vtab.idxNum, p->u.vtab.idxStr, p->u.vtab.omitMask);
-    }else{
-      z = sqlite3_mprintf("(%d,%x)", p->u.vtab.idxNum, p->u.vtab.omitMask);
-    }
-    sqlite3DebugPrintf(" %-19s", z);
-    sqlite3_free(z);
-  }
-  sqlite3DebugPrintf(" f %04x N %d", p->wsFlags, p->nLTerm);
-  sqlite3DebugPrintf(" cost %d,%d,%d\n", p->rSetup, p->rRun, p->nOut);
-}
-#endif
-
-/*
-** Convert bulk memory into a valid WhereLoop that can be passed
-** to whereLoopClear harmlessly.
-*/
-static void whereLoopInit(WhereLoop *p){
-  p->aLTerm = p->aLTermSpace;
-  p->nLTerm = 0;
-  p->nLSlot = ArraySize(p->aLTermSpace);
-  p->wsFlags = 0;
-}
-
-/*
-** Clear the WhereLoop.u union.  Leave WhereLoop.pLTerm intact.
-*/
-static void whereLoopClearUnion(sqlite3 *db, WhereLoop *p){
-  if( p->wsFlags & (WHERE_VIRTUALTABLE|WHERE_AUTO_INDEX) ){
-    if( (p->wsFlags & WHERE_VIRTUALTABLE)!=0 && p->u.vtab.needFree ){
-      sqlite3_free(p->u.vtab.idxStr);
-      p->u.vtab.needFree = 0;
-      p->u.vtab.idxStr = 0;
-    }else if( (p->wsFlags & WHERE_AUTO_INDEX)!=0 && p->u.btree.pIndex!=0 ){
-      sqlite3DbFree(db, p->u.btree.pIndex->zColAff);
-      sqlite3DbFree(db, p->u.btree.pIndex);
-      p->u.btree.pIndex = 0;
-    }
-  }
-}
-
-/*
-** Deallocate internal memory used by a WhereLoop object
-*/
-static void whereLoopClear(sqlite3 *db, WhereLoop *p){
-  if( p->aLTerm!=p->aLTermSpace ) sqlite3DbFree(db, p->aLTerm);
-  whereLoopClearUnion(db, p);
-  whereLoopInit(p);
-}
-
-/*
-** Increase the memory allocation for pLoop->aLTerm[] to be at least n.
-*/
-static int whereLoopResize(sqlite3 *db, WhereLoop *p, int n){
-  WhereTerm **paNew;
-  if( p->nLSlot>=n ) return SQLITE_OK;
-  n = (n+7)&~7;
-  paNew = sqlite3DbMallocRaw(db, sizeof(p->aLTerm[0])*n);
-  if( paNew==0 ) return SQLITE_NOMEM;
-  memcpy(paNew, p->aLTerm, sizeof(p->aLTerm[0])*p->nLSlot);
-  if( p->aLTerm!=p->aLTermSpace ) sqlite3DbFree(db, p->aLTerm);
-  p->aLTerm = paNew;
-  p->nLSlot = n;
-  return SQLITE_OK;
-}
-
-/*
-** Transfer content from the second pLoop into the first.
-*/
-static int whereLoopXfer(sqlite3 *db, WhereLoop *pTo, WhereLoop *pFrom){
-  whereLoopClearUnion(db, pTo);
-  if( whereLoopResize(db, pTo, pFrom->nLTerm) ){
-    memset(&pTo->u, 0, sizeof(pTo->u));
-    return SQLITE_NOMEM;
-  }
-  memcpy(pTo, pFrom, WHERE_LOOP_XFER_SZ);
-  memcpy(pTo->aLTerm, pFrom->aLTerm, pTo->nLTerm*sizeof(pTo->aLTerm[0]));
-  if( pFrom->wsFlags & WHERE_VIRTUALTABLE ){
-    pFrom->u.vtab.needFree = 0;
-  }else if( (pFrom->wsFlags & WHERE_AUTO_INDEX)!=0 ){
-    pFrom->u.btree.pIndex = 0;
-  }
-  return SQLITE_OK;
-}
-
-/*
-** Delete a WhereLoop object
-*/
-static void whereLoopDelete(sqlite3 *db, WhereLoop *p){
-  whereLoopClear(db, p);
-  sqlite3DbFree(db, p);
-}
-
-/*
-** Free a WhereInfo structure
-*/
-static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
-  if( ALWAYS(pWInfo) ){
-    whereClauseClear(&pWInfo->sWC);
-    while( pWInfo->pLoops ){
-      WhereLoop *p = pWInfo->pLoops;
-      pWInfo->pLoops = p->pNextLoop;
-      whereLoopDelete(db, p);
-    }
-    sqlite3DbFree(db, pWInfo);
-  }
-}
-
-/*
-** Insert or replace a WhereLoop entry using the template supplied.
-**
-** An existing WhereLoop entry might be overwritten if the new template
-** is better and has fewer dependencies.  Or the template will be ignored
-** and no insert will occur if an existing WhereLoop is faster and has
-** fewer dependencies than the template.  Otherwise a new WhereLoop is
-** added based on the template.
-**
-** If pBuilder->pOrSet is not NULL then we only care about only the
-** prerequisites and rRun and nOut costs of the N best loops.  That
-** information is gathered in the pBuilder->pOrSet object.  This special
-** processing mode is used only for OR clause processing.
-**
-** When accumulating multiple loops (when pBuilder->pOrSet is NULL) we
-** still might overwrite similar loops with the new template if the
-** template is better.  Loops may be overwritten if the following 
-** conditions are met:
-**
-**    (1)  They have the same iTab.
-**    (2)  They have the same iSortIdx.
-**    (3)  The template has same or fewer dependencies than the current loop
-**    (4)  The template has the same or lower cost than the current loop
-**    (5)  The template uses more terms of the same index but has no additional
-**         dependencies          
-*/
-static int whereLoopInsert(WhereLoopBuilder *pBuilder, WhereLoop *pTemplate){
-  WhereLoop **ppPrev, *p, *pNext = 0;
-  WhereInfo *pWInfo = pBuilder->pWInfo;
-  sqlite3 *db = pWInfo->pParse->db;
-
-  /* If pBuilder->pOrSet is defined, then only keep track of the costs
-  ** and prereqs.
-  */
-  if( pBuilder->pOrSet!=0 ){
-#if WHERETRACE_ENABLED
-    u16 n = pBuilder->pOrSet->n;
-    int x =
-#endif
-    whereOrInsert(pBuilder->pOrSet, pTemplate->prereq, pTemplate->rRun,
-                                    pTemplate->nOut);
-#if WHERETRACE_ENABLED
-    if( sqlite3WhereTrace & 0x8 ){
-      sqlite3DebugPrintf(x?"   or-%d:  ":"   or-X:  ", n);
-      whereLoopPrint(pTemplate, pWInfo->pTabList);
-    }
-#endif
-    return SQLITE_OK;
-  }
-
-  /* Search for an existing WhereLoop to overwrite, or which takes
-  ** priority over pTemplate.
-  */
-  for(ppPrev=&pWInfo->pLoops, p=*ppPrev; p; ppPrev=&p->pNextLoop, p=*ppPrev){
-    if( p->iTab!=pTemplate->iTab || p->iSortIdx!=pTemplate->iSortIdx ){
-      /* If either the iTab or iSortIdx values for two WhereLoop are different
-      ** then those WhereLoops need to be considered separately.  Neither is
-      ** a candidate to replace the other. */
-      continue;
-    }
-    /* In the current implementation, the rSetup value is either zero
-    ** or the cost of building an automatic index (NlogN) and the NlogN
-    ** is the same for compatible WhereLoops. */
-    assert( p->rSetup==0 || pTemplate->rSetup==0 
-                 || p->rSetup==pTemplate->rSetup );
-
-    /* whereLoopAddBtree() always generates and inserts the automatic index
-    ** case first.  Hence compatible candidate WhereLoops never have a larger
-    ** rSetup. Call this SETUP-INVARIANT */
-    assert( p->rSetup>=pTemplate->rSetup );
-
-    if( (p->prereq & pTemplate->prereq)==p->prereq
-     && p->rSetup<=pTemplate->rSetup
-     && p->rRun<=pTemplate->rRun
-     && p->nOut<=pTemplate->nOut
-    ){
-      /* This branch taken when p is equal or better than pTemplate in 
-      ** all of (1) dependencies (2) setup-cost, (3) run-cost, and
-      ** (4) number of output rows. */
-      assert( p->rSetup==pTemplate->rSetup );
-      if( p->prereq==pTemplate->prereq
-       && p->nLTerm<pTemplate->nLTerm
-       && (p->wsFlags & pTemplate->wsFlags & WHERE_INDEXED)!=0
-       && (p->u.btree.pIndex==pTemplate->u.btree.pIndex
-          || pTemplate->rRun+p->nLTerm<=p->rRun+pTemplate->nLTerm)
-      ){
-        /* Overwrite an existing WhereLoop with an similar one that uses
-        ** more terms of the index */
-        pNext = p->pNextLoop;
-        break;
-      }else{
-        /* pTemplate is not helpful.
-        ** Return without changing or adding anything */
-        goto whereLoopInsert_noop;
-      }
-    }
-    if( (p->prereq & pTemplate->prereq)==pTemplate->prereq
-     && p->rRun>=pTemplate->rRun
-     && p->nOut>=pTemplate->nOut
-    ){
-      /* Overwrite an existing WhereLoop with a better one: one that is
-      ** better at one of (1) dependencies, (2) setup-cost, (3) run-cost
-      ** or (4) number of output rows, and is no worse in any of those
-      ** categories. */
-      assert( p->rSetup>=pTemplate->rSetup ); /* SETUP-INVARIANT above */
-      pNext = p->pNextLoop;
-      break;
-    }
-  }
-
-  /* If we reach this point it means that either p[] should be overwritten
-  ** with pTemplate[] if p[] exists, or if p==NULL then allocate a new
-  ** WhereLoop and insert it.
-  */
-#if WHERETRACE_ENABLED
-  if( sqlite3WhereTrace & 0x8 ){
-    if( p!=0 ){
-      sqlite3DebugPrintf("ins-del:  ");
-      whereLoopPrint(p, pWInfo->pTabList);
-    }
-    sqlite3DebugPrintf("ins-new:  ");
-    whereLoopPrint(pTemplate, pWInfo->pTabList);
-  }
-#endif
-  if( p==0 ){
-    p = sqlite3DbMallocRaw(db, sizeof(WhereLoop));
-    if( p==0 ) return SQLITE_NOMEM;
-    whereLoopInit(p);
-  }
-  whereLoopXfer(db, p, pTemplate);
-  p->pNextLoop = pNext;
-  *ppPrev = p;
-  if( (p->wsFlags & WHERE_VIRTUALTABLE)==0 ){
-    Index *pIndex = p->u.btree.pIndex;
-    if( pIndex && pIndex->tnum==0 ){
-      p->u.btree.pIndex = 0;
-    }
-  }
-  return SQLITE_OK;
-
-  /* Jump here if the insert is a no-op */
-whereLoopInsert_noop:
-#if WHERETRACE_ENABLED
-  if( sqlite3WhereTrace & 0x8 ){
-    sqlite3DebugPrintf("ins-noop: ");
-    whereLoopPrint(pTemplate, pWInfo->pTabList);
-  }
-#endif
-  return SQLITE_OK;  
-}
-
-/*
-** Adjust the WhereLoop.nOut value downward to account for terms of the
-** WHERE clause that reference the loop but which are not used by an
-** index.
-**
-** In the current implementation, the first extra WHERE clause term reduces
-** the number of output rows by a factor of 10 and each additional term
-** reduces the number of output rows by sqrt(2).
-*/
-static void whereLoopOutputAdjust(WhereClause *pWC, WhereLoop *pLoop){
-  WhereTerm *pTerm, *pX;
-  Bitmask notAllowed = ~(pLoop->prereq|pLoop->maskSelf);
-  int i, j;
-
-  if( !OptimizationEnabled(pWC->pWInfo->pParse->db, SQLITE_AdjustOutEst) ){
-    return;
-  }
-  for(i=pWC->nTerm, pTerm=pWC->a; i>0; i--, pTerm++){
-    if( (pTerm->wtFlags & TERM_VIRTUAL)!=0 ) break;
-    if( (pTerm->prereqAll & pLoop->maskSelf)==0 ) continue;
-    if( (pTerm->prereqAll & notAllowed)!=0 ) continue;
-    for(j=pLoop->nLTerm-1; j>=0; j--){
-      pX = pLoop->aLTerm[j];
-      if( pX==pTerm ) break;
-      if( pX->iParent>=0 && (&pWC->a[pX->iParent])==pTerm ) break;
-    }
-    if( j<0 ) pLoop->nOut += pTerm->truthProb;
-  }
-}
-
-/*
-** We have so far matched pBuilder->pNew->u.btree.nEq terms of the index pIndex.
-** Try to match one more.
-**
-** If pProbe->tnum==0, that means pIndex is a fake index used for the
-** INTEGER PRIMARY KEY.
-*/
-static int whereLoopAddBtreeIndex(
-  WhereLoopBuilder *pBuilder,     /* The WhereLoop factory */
-  struct SrcList_item *pSrc,      /* FROM clause term being analyzed */
-  Index *pProbe,                  /* An index on pSrc */
-  LogEst nInMul                   /* log(Number of iterations due to IN) */
-){
-  WhereInfo *pWInfo = pBuilder->pWInfo;  /* WHERE analyse context */
-  Parse *pParse = pWInfo->pParse;        /* Parsing context */
-  sqlite3 *db = pParse->db;       /* Database connection malloc context */
-  WhereLoop *pNew;                /* Template WhereLoop under construction */
-  WhereTerm *pTerm;               /* A WhereTerm under consideration */
-  int opMask;                     /* Valid operators for constraints */
-  WhereScan scan;                 /* Iterator for WHERE terms */
-  Bitmask saved_prereq;           /* Original value of pNew->prereq */
-  u16 saved_nLTerm;               /* Original value of pNew->nLTerm */
-  int saved_nEq;                  /* Original value of pNew->u.btree.nEq */
-  u32 saved_wsFlags;              /* Original value of pNew->wsFlags */
-  LogEst saved_nOut;              /* Original value of pNew->nOut */
-  int iCol;                       /* Index of the column in the table */
-  int rc = SQLITE_OK;             /* Return code */
-  LogEst nRowEst;                 /* Estimated index selectivity */
-  LogEst rLogSize;                /* Logarithm of table size */
-  WhereTerm *pTop = 0, *pBtm = 0; /* Top and bottom range constraints */
-
-  pNew = pBuilder->pNew;
-  if( db->mallocFailed ) return SQLITE_NOMEM;
-
-  assert( (pNew->wsFlags & WHERE_VIRTUALTABLE)==0 );
-  assert( (pNew->wsFlags & WHERE_TOP_LIMIT)==0 );
-  if( pNew->wsFlags & WHERE_BTM_LIMIT ){
-    opMask = WO_LT|WO_LE;
-  }else if( pProbe->tnum<=0 || (pSrc->jointype & JT_LEFT)!=0 ){
-    opMask = WO_EQ|WO_IN|WO_GT|WO_GE|WO_LT|WO_LE;
-  }else{
-    opMask = WO_EQ|WO_IN|WO_ISNULL|WO_GT|WO_GE|WO_LT|WO_LE;
-  }
-  if( pProbe->bUnordered ) opMask &= ~(WO_GT|WO_GE|WO_LT|WO_LE);
-
-  assert( pNew->u.btree.nEq<=pProbe->nColumn );
-  if( pNew->u.btree.nEq < pProbe->nColumn ){
-    iCol = pProbe->aiColumn[pNew->u.btree.nEq];
-    nRowEst = sqlite3LogEst(pProbe->aiRowEst[pNew->u.btree.nEq+1]);
-    if( nRowEst==0 && pProbe->onError==OE_None ) nRowEst = 1;
-  }else{
-    iCol = -1;
-    nRowEst = 0;
-  }
-  pTerm = whereScanInit(&scan, pBuilder->pWC, pSrc->iCursor, iCol,
-                        opMask, pProbe);
-  saved_nEq = pNew->u.btree.nEq;
-  saved_nLTerm = pNew->nLTerm;
-  saved_wsFlags = pNew->wsFlags;
-  saved_prereq = pNew->prereq;
-  saved_nOut = pNew->nOut;
-  pNew->rSetup = 0;
-  rLogSize = estLog(sqlite3LogEst(pProbe->aiRowEst[0]));
-  for(; rc==SQLITE_OK && pTerm!=0; pTerm = whereScanNext(&scan)){
-    int nIn = 0;
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-    int nRecValid = pBuilder->nRecValid;
-#endif
-    if( (pTerm->eOperator==WO_ISNULL || (pTerm->wtFlags&TERM_VNULL)!=0)
-     && (iCol<0 || pSrc->pTab->aCol[iCol].notNull)
-    ){
-      continue; /* ignore IS [NOT] NULL constraints on NOT NULL columns */
-    }
-    if( pTerm->prereqRight & pNew->maskSelf ) continue;
-
-    assert( pNew->nOut==saved_nOut );
-
-    pNew->wsFlags = saved_wsFlags;
-    pNew->u.btree.nEq = saved_nEq;
-    pNew->nLTerm = saved_nLTerm;
-    if( whereLoopResize(db, pNew, pNew->nLTerm+1) ) break; /* OOM */
-    pNew->aLTerm[pNew->nLTerm++] = pTerm;
-    pNew->prereq = (saved_prereq | pTerm->prereqRight) & ~pNew->maskSelf;
-    pNew->rRun = rLogSize; /* Baseline cost is log2(N).  Adjustments below */
-    if( pTerm->eOperator & WO_IN ){
-      Expr *pExpr = pTerm->pExpr;
-      pNew->wsFlags |= WHERE_COLUMN_IN;
-      if( ExprHasProperty(pExpr, EP_xIsSelect) ){
-        /* "x IN (SELECT ...)":  TUNING: the SELECT returns 25 rows */
-        nIn = 46;  assert( 46==sqlite3LogEst(25) );
-      }else if( ALWAYS(pExpr->x.pList && pExpr->x.pList->nExpr) ){
-        /* "x IN (value, value, ...)" */
-        nIn = sqlite3LogEst(pExpr->x.pList->nExpr);
-      }
-      pNew->rRun += nIn;
-      pNew->u.btree.nEq++;
-      pNew->nOut = nRowEst + nInMul + nIn;
-    }else if( pTerm->eOperator & (WO_EQ) ){
-      assert( (pNew->wsFlags & (WHERE_COLUMN_NULL|WHERE_COLUMN_IN))!=0
-                  || nInMul==0 );
-      pNew->wsFlags |= WHERE_COLUMN_EQ;
-      if( iCol<0  
-       || (pProbe->onError!=OE_None && nInMul==0
-           && pNew->u.btree.nEq==pProbe->nColumn-1)
-      ){
-        assert( (pNew->wsFlags & WHERE_COLUMN_IN)==0 || iCol<0 );
-        pNew->wsFlags |= WHERE_ONEROW;
-      }
-      pNew->u.btree.nEq++;
-      pNew->nOut = nRowEst + nInMul;
-    }else if( pTerm->eOperator & (WO_ISNULL) ){
-      pNew->wsFlags |= WHERE_COLUMN_NULL;
-      pNew->u.btree.nEq++;
-      /* TUNING: IS NULL selects 2 rows */
-      nIn = 10;  assert( 10==sqlite3LogEst(2) );
-      pNew->nOut = nRowEst + nInMul + nIn;
-    }else if( pTerm->eOperator & (WO_GT|WO_GE) ){
-      testcase( pTerm->eOperator & WO_GT );
-      testcase( pTerm->eOperator & WO_GE );
-      pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_BTM_LIMIT;
-      pBtm = pTerm;
-      pTop = 0;
-    }else{
-      assert( pTerm->eOperator & (WO_LT|WO_LE) );
-      testcase( pTerm->eOperator & WO_LT );
-      testcase( pTerm->eOperator & WO_LE );
-      pNew->wsFlags |= WHERE_COLUMN_RANGE|WHERE_TOP_LIMIT;
-      pTop = pTerm;
-      pBtm = (pNew->wsFlags & WHERE_BTM_LIMIT)!=0 ?
-                     pNew->aLTerm[pNew->nLTerm-2] : 0;
-    }
-    if( pNew->wsFlags & WHERE_COLUMN_RANGE ){
-      /* Adjust nOut and rRun for STAT3 range values */
-      assert( pNew->nOut==saved_nOut );
-      whereRangeScanEst(pParse, pBuilder, pBtm, pTop, pNew);
-    }
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-    if( nInMul==0 
-     && pProbe->nSample 
-     && pNew->u.btree.nEq<=pProbe->nSampleCol
-     && OptimizationEnabled(db, SQLITE_Stat3) 
-    ){
-      Expr *pExpr = pTerm->pExpr;
-      tRowcnt nOut = 0;
-      if( (pTerm->eOperator & (WO_EQ|WO_ISNULL))!=0 ){
-        testcase( pTerm->eOperator & WO_EQ );
-        testcase( pTerm->eOperator & WO_ISNULL );
-        rc = whereEqualScanEst(pParse, pBuilder, pExpr->pRight, &nOut);
-      }else if( (pTerm->eOperator & WO_IN)
-             &&  !ExprHasProperty(pExpr, EP_xIsSelect)  ){
-        rc = whereInScanEst(pParse, pBuilder, pExpr->x.pList, &nOut);
-      }
-      assert( nOut==0 || rc==SQLITE_OK );
-      if( nOut ){
-        pNew->nOut = sqlite3LogEst(nOut);
-        if( pNew->nOut>saved_nOut ) pNew->nOut = saved_nOut;
-      }
-    }
-#endif
-    if( (pNew->wsFlags & (WHERE_IDX_ONLY|WHERE_IPK))==0 ){
-      /* Each row involves a step of the index, then a binary search of
-      ** the main table */
-      pNew->rRun =  sqlite3LogEstAdd(pNew->rRun,rLogSize>27 ? rLogSize-17 : 10);
-    }
-    /* Step cost for each output row */
-    pNew->rRun = sqlite3LogEstAdd(pNew->rRun, pNew->nOut);
-    whereLoopOutputAdjust(pBuilder->pWC, pNew);
-    rc = whereLoopInsert(pBuilder, pNew);
-    if( (pNew->wsFlags & WHERE_TOP_LIMIT)==0
-     && pNew->u.btree.nEq<(pProbe->nColumn + (pProbe->zName!=0))
-    ){
-      whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, nInMul+nIn);
-    }
-    pNew->nOut = saved_nOut;
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-    pBuilder->nRecValid = nRecValid;
-#endif
-  }
-  pNew->prereq = saved_prereq;
-  pNew->u.btree.nEq = saved_nEq;
-  pNew->wsFlags = saved_wsFlags;
-  pNew->nOut = saved_nOut;
-  pNew->nLTerm = saved_nLTerm;
-  return rc;
-}
-
-/*
-** Return True if it is possible that pIndex might be useful in
-** implementing the ORDER BY clause in pBuilder.
-**
-** Return False if pBuilder does not contain an ORDER BY clause or
-** if there is no way for pIndex to be useful in implementing that
-** ORDER BY clause.
-*/
-static int indexMightHelpWithOrderBy(
-  WhereLoopBuilder *pBuilder,
-  Index *pIndex,
-  int iCursor
-){
-  ExprList *pOB;
-  int ii, jj;
-
-  if( pIndex->bUnordered ) return 0;
-  if( (pOB = pBuilder->pWInfo->pOrderBy)==0 ) return 0;
-  for(ii=0; ii<pOB->nExpr; ii++){
-    Expr *pExpr = sqlite3ExprSkipCollate(pOB->a[ii].pExpr);
-    if( pExpr->op!=TK_COLUMN ) return 0;
-    if( pExpr->iTable==iCursor ){
-      for(jj=0; jj<pIndex->nColumn; jj++){
-        if( pExpr->iColumn==pIndex->aiColumn[jj] ) return 1;
-      }
-    }
-  }
-  return 0;
-}
-
-/*
-** Return a bitmask where 1s indicate that the corresponding column of
-** the table is used by an index.  Only the first 63 columns are considered.
-*/
-static Bitmask columnsInIndex(Index *pIdx){
-  Bitmask m = 0;
-  int j;
-  for(j=pIdx->nColumn-1; j>=0; j--){
-    int x = pIdx->aiColumn[j];
-    assert( x>=0 );
-    testcase( x==BMS-1 );
-    testcase( x==BMS-2 );
-    if( x<BMS-1 ) m |= MASKBIT(x);
-  }
-  return m;
-}
-
-/* Check to see if a partial index with pPartIndexWhere can be used
-** in the current query.  Return true if it can be and false if not.
-*/
-static int whereUsablePartialIndex(int iTab, WhereClause *pWC, Expr *pWhere){
-  int i;
-  WhereTerm *pTerm;
-  for(i=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
-    if( sqlite3ExprImpliesExpr(pTerm->pExpr, pWhere, iTab) ) return 1;
-  }
-  return 0;
-}
-
-/*
-** Add all WhereLoop objects for a single table of the join where the table
-** is idenfied by pBuilder->pNew->iTab.  That table is guaranteed to be
-** a b-tree table, not a virtual table.
-*/
-static int whereLoopAddBtree(
-  WhereLoopBuilder *pBuilder, /* WHERE clause information */
-  Bitmask mExtra              /* Extra prerequesites for using this table */
-){
-  WhereInfo *pWInfo;          /* WHERE analysis context */
-  Index *pProbe;              /* An index we are evaluating */
-  Index sPk;                  /* A fake index object for the primary key */
-  tRowcnt aiRowEstPk[2];      /* The aiRowEst[] value for the sPk index */
-  int aiColumnPk = -1;        /* The aColumn[] value for the sPk index */
-  SrcList *pTabList;          /* The FROM clause */
-  struct SrcList_item *pSrc;  /* The FROM clause btree term to add */
-  WhereLoop *pNew;            /* Template WhereLoop object */
-  int rc = SQLITE_OK;         /* Return code */
-  int iSortIdx = 1;           /* Index number */
-  int b;                      /* A boolean value */
-  LogEst rSize;               /* number of rows in the table */
-  LogEst rLogSize;            /* Logarithm of the number of rows in the table */
-  WhereClause *pWC;           /* The parsed WHERE clause */
-  Table *pTab;                /* Table being queried */
-  
-  pNew = pBuilder->pNew;
-  pWInfo = pBuilder->pWInfo;
-  pTabList = pWInfo->pTabList;
-  pSrc = pTabList->a + pNew->iTab;
-  pTab = pSrc->pTab;
-  pWC = pBuilder->pWC;
-  assert( !IsVirtual(pSrc->pTab) );
-
-  if( pSrc->pIndex ){
-    /* An INDEXED BY clause specifies a particular index to use */
-    pProbe = pSrc->pIndex;
-  }else{
-    /* There is no INDEXED BY clause.  Create a fake Index object in local
-    ** variable sPk to represent the rowid primary key index.  Make this
-    ** fake index the first in a chain of Index objects with all of the real
-    ** indices to follow */
-    Index *pFirst;                  /* First of real indices on the table */
-    memset(&sPk, 0, sizeof(Index));
-    sPk.nColumn = 1;
-    sPk.aiColumn = &aiColumnPk;
-    sPk.aiRowEst = aiRowEstPk;
-    sPk.onError = OE_Replace;
-    sPk.pTable = pTab;
-    aiRowEstPk[0] = pTab->nRowEst;
-    aiRowEstPk[1] = 1;
-    pFirst = pSrc->pTab->pIndex;
-    if( pSrc->notIndexed==0 ){
-      /* The real indices of the table are only considered if the
-      ** NOT INDEXED qualifier is omitted from the FROM clause */
-      sPk.pNext = pFirst;
-    }
-    pProbe = &sPk;
-  }
-  rSize = sqlite3LogEst(pTab->nRowEst);
-  rLogSize = estLog(rSize);
-
-#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
-  /* Automatic indexes */
-  if( !pBuilder->pOrSet
-   && (pWInfo->pParse->db->flags & SQLITE_AutoIndex)!=0
-   && pSrc->pIndex==0
-   && !pSrc->viaCoroutine
-   && !pSrc->notIndexed
-   && !pSrc->isCorrelated
-  ){
-    /* Generate auto-index WhereLoops */
-    WhereTerm *pTerm;
-    WhereTerm *pWCEnd = pWC->a + pWC->nTerm;
-    for(pTerm=pWC->a; rc==SQLITE_OK && pTerm<pWCEnd; pTerm++){
-      if( pTerm->prereqRight & pNew->maskSelf ) continue;
-      if( termCanDriveIndex(pTerm, pSrc, 0) ){
-        pNew->u.btree.nEq = 1;
-        pNew->u.btree.pIndex = 0;
-        pNew->nLTerm = 1;
-        pNew->aLTerm[0] = pTerm;
-        /* TUNING: One-time cost for computing the automatic index is
-        ** approximately 7*N*log2(N) where N is the number of rows in
-        ** the table being indexed. */
-        pNew->rSetup = rLogSize + rSize + 28;  assert( 28==sqlite3LogEst(7) );
-        /* TUNING: Each index lookup yields 20 rows in the table.  This
-        ** is more than the usual guess of 10 rows, since we have no way
-        ** of knowning how selective the index will ultimately be.  It would
-        ** not be unreasonable to make this value much larger. */
-        pNew->nOut = 43;  assert( 43==sqlite3LogEst(20) );
-        pNew->rRun = sqlite3LogEstAdd(rLogSize,pNew->nOut);
-        pNew->wsFlags = WHERE_AUTO_INDEX;
-        pNew->prereq = mExtra | pTerm->prereqRight;
-        rc = whereLoopInsert(pBuilder, pNew);
-      }
-    }
-  }
-#endif /* SQLITE_OMIT_AUTOMATIC_INDEX */
-
-  /* Loop over all indices
-  */
-  for(; rc==SQLITE_OK && pProbe; pProbe=pProbe->pNext, iSortIdx++){
-    if( pProbe->pPartIdxWhere!=0
-     && !whereUsablePartialIndex(pNew->iTab, pWC, pProbe->pPartIdxWhere) ){
-      continue;  /* Partial index inappropriate for this query */
-    }
-    pNew->u.btree.nEq = 0;
-    pNew->nLTerm = 0;
-    pNew->iSortIdx = 0;
-    pNew->rSetup = 0;
-    pNew->prereq = mExtra;
-    pNew->nOut = rSize;
-    pNew->u.btree.pIndex = pProbe;
-    b = indexMightHelpWithOrderBy(pBuilder, pProbe, pSrc->iCursor);
-    /* The ONEPASS_DESIRED flags never occurs together with ORDER BY */
-    assert( (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || b==0 );
-    if( pProbe->tnum<=0 ){
-      /* Integer primary key index */
-      pNew->wsFlags = WHERE_IPK;
-
-      /* Full table scan */
-      pNew->iSortIdx = b ? iSortIdx : 0;
-      /* TUNING: Cost of full table scan is 3*(N + log2(N)).
-      **  +  The extra 3 factor is to encourage the use of indexed lookups
-      **     over full scans.  FIXME */
-      pNew->rRun = sqlite3LogEstAdd(rSize,rLogSize) + 16;
-      whereLoopOutputAdjust(pWC, pNew);
-      rc = whereLoopInsert(pBuilder, pNew);
-      pNew->nOut = rSize;
-      if( rc ) break;
-    }else{
-      Bitmask m = pSrc->colUsed & ~columnsInIndex(pProbe);
-      pNew->wsFlags = (m==0) ? (WHERE_IDX_ONLY|WHERE_INDEXED) : WHERE_INDEXED;
-
-      /* Full scan via index */
-      if( b
-       || ( m==0
-         && pProbe->bUnordered==0
-         && pProbe->szIdxRow<pTab->szTabRow
-         && (pWInfo->wctrlFlags & WHERE_ONEPASS_DESIRED)==0
-         && sqlite3GlobalConfig.bUseCis
-         && OptimizationEnabled(pWInfo->pParse->db, SQLITE_CoverIdxScan)
-          )
-      ){
-        pNew->iSortIdx = b ? iSortIdx : 0;
-        if( m==0 ){
-          /* TUNING: Cost of a covering index scan is K*(N + log2(N)).
-          **  +  The extra factor K of between 1.1 and 3.0 that depends
-          **     on the relative sizes of the table and the index.  K
-          **     is smaller for smaller indices, thus favoring them.
-          */
-          pNew->rRun = sqlite3LogEstAdd(rSize,rLogSize) + 1 +
-                        (15*pProbe->szIdxRow)/pTab->szTabRow;
-        }else{
-          assert( b!=0 ); 
-          /* TUNING: Cost of scanning a non-covering index is (N+1)*log2(N)
-          ** which we will simplify to just N*log2(N) */
-          pNew->rRun = rSize + rLogSize;
-        }
-        whereLoopOutputAdjust(pWC, pNew);
-        rc = whereLoopInsert(pBuilder, pNew);
-        pNew->nOut = rSize;
-        if( rc ) break;
-      }
-    }
-
-    rc = whereLoopAddBtreeIndex(pBuilder, pSrc, pProbe, 0);
-#ifdef SQLITE_ENABLE_STAT3_OR_STAT4
-    sqlite3Stat4ProbeFree(pBuilder->pRec);
-    pBuilder->nRecValid = 0;
-    pBuilder->pRec = 0;
-#endif
-
-    /* If there was an INDEXED BY clause, then only that one index is
-    ** considered. */
-    if( pSrc->pIndex ) break;
-  }
-  return rc;
-}
-
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-/*
-** Add all WhereLoop objects for a table of the join identified by
-** pBuilder->pNew->iTab.  That table is guaranteed to be a virtual table.
-*/
-static int whereLoopAddVirtual(
-  WhereLoopBuilder *pBuilder   /* WHERE clause information */
-){
-  WhereInfo *pWInfo;           /* WHERE analysis context */
-  Parse *pParse;               /* The parsing context */
-  WhereClause *pWC;            /* The WHERE clause */
-  struct SrcList_item *pSrc;   /* The FROM clause term to search */
-  Table *pTab;
-  sqlite3 *db;
-  sqlite3_index_info *pIdxInfo;
-  struct sqlite3_index_constraint *pIdxCons;
-  struct sqlite3_index_constraint_usage *pUsage;
-  WhereTerm *pTerm;
-  int i, j;
-  int iTerm, mxTerm;
-  int nConstraint;
-  int seenIn = 0;              /* True if an IN operator is seen */
-  int seenVar = 0;             /* True if a non-constant constraint is seen */
-  int iPhase;                  /* 0: const w/o IN, 1: const, 2: no IN,  2: IN */
-  WhereLoop *pNew;
-  int rc = SQLITE_OK;
-
-  pWInfo = pBuilder->pWInfo;
-  pParse = pWInfo->pParse;
-  db = pParse->db;
-  pWC = pBuilder->pWC;
-  pNew = pBuilder->pNew;
-  pSrc = &pWInfo->pTabList->a[pNew->iTab];
-  pTab = pSrc->pTab;
-  assert( IsVirtual(pTab) );
-  pIdxInfo = allocateIndexInfo(pParse, pWC, pSrc, pBuilder->pOrderBy);
-  if( pIdxInfo==0 ) return SQLITE_NOMEM;
-  pNew->prereq = 0;
-  pNew->rSetup = 0;
-  pNew->wsFlags = WHERE_VIRTUALTABLE;
-  pNew->nLTerm = 0;
-  pNew->u.vtab.needFree = 0;
-  pUsage = pIdxInfo->aConstraintUsage;
-  nConstraint = pIdxInfo->nConstraint;
-  if( whereLoopResize(db, pNew, nConstraint) ){
-    sqlite3DbFree(db, pIdxInfo);
-    return SQLITE_NOMEM;
-  }
-
-  for(iPhase=0; iPhase<=3; iPhase++){
-    if( !seenIn && (iPhase&1)!=0 ){
-      iPhase++;
-      if( iPhase>3 ) break;
-    }
-    if( !seenVar && iPhase>1 ) break;
-    pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
-    for(i=0; i<pIdxInfo->nConstraint; i++, pIdxCons++){
-      j = pIdxCons->iTermOffset;
-      pTerm = &pWC->a[j];
-      switch( iPhase ){
-        case 0:    /* Constants without IN operator */
-          pIdxCons->usable = 0;
-          if( (pTerm->eOperator & WO_IN)!=0 ){
-            seenIn = 1;
-          }
-          if( pTerm->prereqRight!=0 ){
-            seenVar = 1;
-          }else if( (pTerm->eOperator & WO_IN)==0 ){
-            pIdxCons->usable = 1;
-          }
-          break;
-        case 1:    /* Constants with IN operators */
-          assert( seenIn );
-          pIdxCons->usable = (pTerm->prereqRight==0);
-          break;
-        case 2:    /* Variables without IN */
-          assert( seenVar );
-          pIdxCons->usable = (pTerm->eOperator & WO_IN)==0;
-          break;
-        default:   /* Variables with IN */
-          assert( seenVar && seenIn );
-          pIdxCons->usable = 1;
-          break;
-      }
-    }
-    memset(pUsage, 0, sizeof(pUsage[0])*pIdxInfo->nConstraint);
-    if( pIdxInfo->needToFreeIdxStr ) sqlite3_free(pIdxInfo->idxStr);
-    pIdxInfo->idxStr = 0;
-    pIdxInfo->idxNum = 0;
-    pIdxInfo->needToFreeIdxStr = 0;
-    pIdxInfo->orderByConsumed = 0;
-    pIdxInfo->estimatedCost = SQLITE_BIG_DBL / (double)2;
-    rc = vtabBestIndex(pParse, pTab, pIdxInfo);
-    if( rc ) goto whereLoopAddVtab_exit;
-    pIdxCons = *(struct sqlite3_index_constraint**)&pIdxInfo->aConstraint;
-    pNew->prereq = 0;
-    mxTerm = -1;
-    assert( pNew->nLSlot>=nConstraint );
-    for(i=0; i<nConstraint; i++) pNew->aLTerm[i] = 0;
-    pNew->u.vtab.omitMask = 0;
-    for(i=0; i<nConstraint; i++, pIdxCons++){
-      if( (iTerm = pUsage[i].argvIndex - 1)>=0 ){
-        j = pIdxCons->iTermOffset;
-        if( iTerm>=nConstraint
-         || j<0
-         || j>=pWC->nTerm
-         || pNew->aLTerm[iTerm]!=0
-        ){
-          rc = SQLITE_ERROR;
-          sqlite3ErrorMsg(pParse, "%s.xBestIndex() malfunction", pTab->zName);
-          goto whereLoopAddVtab_exit;
-        }
-        testcase( iTerm==nConstraint-1 );
-        testcase( j==0 );
-        testcase( j==pWC->nTerm-1 );
-        pTerm = &pWC->a[j];
-        pNew->prereq |= pTerm->prereqRight;
-        assert( iTerm<pNew->nLSlot );
-        pNew->aLTerm[iTerm] = pTerm;
-        if( iTerm>mxTerm ) mxTerm = iTerm;
-        testcase( iTerm==15 );
-        testcase( iTerm==16 );
-        if( iTerm<16 && pUsage[i].omit ) pNew->u.vtab.omitMask |= 1<<iTerm;
-        if( (pTerm->eOperator & WO_IN)!=0 ){
-          if( pUsage[i].omit==0 ){
-            /* Do not attempt to use an IN constraint if the virtual table
-            ** says that the equivalent EQ constraint cannot be safely omitted.
-            ** If we do attempt to use such a constraint, some rows might be
-            ** repeated in the output. */
-            break;
-          }
-          /* A virtual table that is constrained by an IN clause may not
-          ** consume the ORDER BY clause because (1) the order of IN terms
-          ** is not necessarily related to the order of output terms and
-          ** (2) Multiple outputs from a single IN value will not merge
-          ** together.  */
-          pIdxInfo->orderByConsumed = 0;
-        }
-      }
-    }
-    if( i>=nConstraint ){
-      pNew->nLTerm = mxTerm+1;
-      assert( pNew->nLTerm<=pNew->nLSlot );
-      pNew->u.vtab.idxNum = pIdxInfo->idxNum;
-      pNew->u.vtab.needFree = pIdxInfo->needToFreeIdxStr;
-      pIdxInfo->needToFreeIdxStr = 0;
-      pNew->u.vtab.idxStr = pIdxInfo->idxStr;
-      pNew->u.vtab.isOrdered = (u8)((pIdxInfo->nOrderBy!=0)
-                                     && pIdxInfo->orderByConsumed);
-      pNew->rSetup = 0;
-      pNew->rRun = sqlite3LogEstFromDouble(pIdxInfo->estimatedCost);
-      /* TUNING: Every virtual table query returns 25 rows */
-      pNew->nOut = 46;  assert( 46==sqlite3LogEst(25) );
-      whereLoopInsert(pBuilder, pNew);
-      if( pNew->u.vtab.needFree ){
-        sqlite3_free(pNew->u.vtab.idxStr);
-        pNew->u.vtab.needFree = 0;
-      }
-    }
-  }  
-
-whereLoopAddVtab_exit:
-  if( pIdxInfo->needToFreeIdxStr ) sqlite3_free(pIdxInfo->idxStr);
-  sqlite3DbFree(db, pIdxInfo);
-  return rc;
-}
-#endif /* SQLITE_OMIT_VIRTUALTABLE */
-
-/*
-** Add WhereLoop entries to handle OR terms.  This works for either
-** btrees or virtual tables.
-*/
-static int whereLoopAddOr(WhereLoopBuilder *pBuilder, Bitmask mExtra){
-  WhereInfo *pWInfo = pBuilder->pWInfo;
-  WhereClause *pWC;
-  WhereLoop *pNew;
-  WhereTerm *pTerm, *pWCEnd;
-  int rc = SQLITE_OK;
-  int iCur;
-  WhereClause tempWC;
-  WhereLoopBuilder sSubBuild;
-  WhereOrSet sSum, sCur, sPrev;
-  struct SrcList_item *pItem;
-  
-  pWC = pBuilder->pWC;
-  if( pWInfo->wctrlFlags & WHERE_AND_ONLY ) return SQLITE_OK;
-  pWCEnd = pWC->a + pWC->nTerm;
-  pNew = pBuilder->pNew;
-  memset(&sSum, 0, sizeof(sSum));
-  pItem = pWInfo->pTabList->a + pNew->iTab;
-  iCur = pItem->iCursor;
-
-  for(pTerm=pWC->a; pTerm<pWCEnd && rc==SQLITE_OK; pTerm++){
-    if( (pTerm->eOperator & WO_OR)!=0
-     && (pTerm->u.pOrInfo->indexable & pNew->maskSelf)!=0 
-    ){
-      WhereClause * const pOrWC = &pTerm->u.pOrInfo->wc;
-      WhereTerm * const pOrWCEnd = &pOrWC->a[pOrWC->nTerm];
-      WhereTerm *pOrTerm;
-      int once = 1;
-      int i, j;
-    
-      sSubBuild = *pBuilder;
-      sSubBuild.pOrderBy = 0;
-      sSubBuild.pOrSet = &sCur;
-
-      for(pOrTerm=pOrWC->a; pOrTerm<pOrWCEnd; pOrTerm++){
-        if( (pOrTerm->eOperator & WO_AND)!=0 ){
-          sSubBuild.pWC = &pOrTerm->u.pAndInfo->wc;
-        }else if( pOrTerm->leftCursor==iCur ){
-          tempWC.pWInfo = pWC->pWInfo;
-          tempWC.pOuter = pWC;
-          tempWC.op = TK_AND;
-          tempWC.nTerm = 1;
-          tempWC.a = pOrTerm;
-          sSubBuild.pWC = &tempWC;
-        }else{
-          continue;
-        }
-        sCur.n = 0;
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-        if( IsVirtual(pItem->pTab) ){
-          rc = whereLoopAddVirtual(&sSubBuild);
-          for(i=0; i<sCur.n; i++) sCur.a[i].prereq |= mExtra;
-        }else
-#endif
-        {
-          rc = whereLoopAddBtree(&sSubBuild, mExtra);
-        }
-        assert( rc==SQLITE_OK || sCur.n==0 );
-        if( sCur.n==0 ){
-          sSum.n = 0;
-          break;
-        }else if( once ){
-          whereOrMove(&sSum, &sCur);
-          once = 0;
-        }else{
-          whereOrMove(&sPrev, &sSum);
-          sSum.n = 0;
-          for(i=0; i<sPrev.n; i++){
-            for(j=0; j<sCur.n; j++){
-              whereOrInsert(&sSum, sPrev.a[i].prereq | sCur.a[j].prereq,
-                            sqlite3LogEstAdd(sPrev.a[i].rRun, sCur.a[j].rRun),
-                            sqlite3LogEstAdd(sPrev.a[i].nOut, sCur.a[j].nOut));
-            }
-          }
-        }
-      }
-      pNew->nLTerm = 1;
-      pNew->aLTerm[0] = pTerm;
-      pNew->wsFlags = WHERE_MULTI_OR;
-      pNew->rSetup = 0;
-      pNew->iSortIdx = 0;
-      memset(&pNew->u, 0, sizeof(pNew->u));
-      for(i=0; rc==SQLITE_OK && i<sSum.n; i++){
-        /* TUNING: Multiple by 3.5 for the secondary table lookup */
-        pNew->rRun = sSum.a[i].rRun + 18;
-        pNew->nOut = sSum.a[i].nOut;
-        pNew->prereq = sSum.a[i].prereq;
-        rc = whereLoopInsert(pBuilder, pNew);
-      }
-    }
-  }
-  return rc;
-}
-
-/*
-** Add all WhereLoop objects for all tables 
-*/
-static int whereLoopAddAll(WhereLoopBuilder *pBuilder){
-  WhereInfo *pWInfo = pBuilder->pWInfo;
-  Bitmask mExtra = 0;
-  Bitmask mPrior = 0;
-  int iTab;
-  SrcList *pTabList = pWInfo->pTabList;
-  struct SrcList_item *pItem;
-  sqlite3 *db = pWInfo->pParse->db;
-  int nTabList = pWInfo->nLevel;
-  int rc = SQLITE_OK;
-  u8 priorJoinType = 0;
-  WhereLoop *pNew;
-
-  /* Loop over the tables in the join, from left to right */
-  pNew = pBuilder->pNew;
-  whereLoopInit(pNew);
-  for(iTab=0, pItem=pTabList->a; iTab<nTabList; iTab++, pItem++){
-    pNew->iTab = iTab;
-    pNew->maskSelf = getMask(&pWInfo->sMaskSet, pItem->iCursor);
-    if( ((pItem->jointype|priorJoinType) & (JT_LEFT|JT_CROSS))!=0 ){
-      mExtra = mPrior;
-    }
-    priorJoinType = pItem->jointype;
-    if( IsVirtual(pItem->pTab) ){
-      rc = whereLoopAddVirtual(pBuilder);
-    }else{
-      rc = whereLoopAddBtree(pBuilder, mExtra);
-    }
-    if( rc==SQLITE_OK ){
-      rc = whereLoopAddOr(pBuilder, mExtra);
-    }
-    mPrior |= pNew->maskSelf;
-    if( rc || db->mallocFailed ) break;
-  }
-  whereLoopClear(db, pNew);
-  return rc;
-}
-
-/*
-** Examine a WherePath (with the addition of the extra WhereLoop of the 5th
-** parameters) to see if it outputs rows in the requested ORDER BY
-** (or GROUP BY) without requiring a separate sort operation.  Return:
-** 
-**    0:  ORDER BY is not satisfied.  Sorting required
-**    1:  ORDER BY is satisfied.      Omit sorting
-**   -1:  Unknown at this time
-**
-** Note that processing for WHERE_GROUPBY and WHERE_DISTINCTBY is not as
-** strict.  With GROUP BY and DISTINCT the only requirement is that
-** equivalent rows appear immediately adjacent to one another.  GROUP BY
-** and DISTINT do not require rows to appear in any particular order as long
-** as equivelent rows are grouped together.  Thus for GROUP BY and DISTINCT
-** the pOrderBy terms can be matched in any order.  With ORDER BY, the 
-** pOrderBy terms must be matched in strict left-to-right order.
-*/
-static int wherePathSatisfiesOrderBy(
-  WhereInfo *pWInfo,    /* The WHERE clause */
-  ExprList *pOrderBy,   /* ORDER BY or GROUP BY or DISTINCT clause to check */
-  WherePath *pPath,     /* The WherePath to check */
-  u16 wctrlFlags,       /* Might contain WHERE_GROUPBY or WHERE_DISTINCTBY */
-  u16 nLoop,            /* Number of entries in pPath->aLoop[] */
-  WhereLoop *pLast,     /* Add this WhereLoop to the end of pPath->aLoop[] */
-  Bitmask *pRevMask     /* OUT: Mask of WhereLoops to run in reverse order */
-){
-  u8 revSet;            /* True if rev is known */
-  u8 rev;               /* Composite sort order */
-  u8 revIdx;            /* Index sort order */
-  u8 isOrderDistinct;   /* All prior WhereLoops are order-distinct */
-  u8 distinctColumns;   /* True if the loop has UNIQUE NOT NULL columns */
-  u8 isMatch;           /* iColumn matches a term of the ORDER BY clause */
-  u16 nColumn;          /* Number of columns in pIndex */
-  u16 nOrderBy;         /* Number terms in the ORDER BY clause */
-  int iLoop;            /* Index of WhereLoop in pPath being processed */
-  int i, j;             /* Loop counters */
-  int iCur;             /* Cursor number for current WhereLoop */
-  int iColumn;          /* A column number within table iCur */
-  WhereLoop *pLoop = 0; /* Current WhereLoop being processed. */
-  WhereTerm *pTerm;     /* A single term of the WHERE clause */
-  Expr *pOBExpr;        /* An expression from the ORDER BY clause */
-  CollSeq *pColl;       /* COLLATE function from an ORDER BY clause term */
-  Index *pIndex;        /* The index associated with pLoop */
-  sqlite3 *db = pWInfo->pParse->db;  /* Database connection */
-  Bitmask obSat = 0;    /* Mask of ORDER BY terms satisfied so far */
-  Bitmask obDone;       /* Mask of all ORDER BY terms */
-  Bitmask orderDistinctMask;  /* Mask of all well-ordered loops */
-  Bitmask ready;              /* Mask of inner loops */
-
-  /*
-  ** We say the WhereLoop is "one-row" if it generates no more than one
-  ** row of output.  A WhereLoop is one-row if all of the following are true:
-  **  (a) All index columns match with WHERE_COLUMN_EQ.
-  **  (b) The index is unique
-  ** Any WhereLoop with an WHERE_COLUMN_EQ constraint on the rowid is one-row.
-  ** Every one-row WhereLoop will have the WHERE_ONEROW bit set in wsFlags.
-  **
-  ** We say the WhereLoop is "order-distinct" if the set of columns from
-  ** that WhereLoop that are in the ORDER BY clause are different for every
-  ** row of the WhereLoop.  Every one-row WhereLoop is automatically
-  ** order-distinct.   A WhereLoop that has no columns in the ORDER BY clause
-  ** is not order-distinct. To be order-distinct is not quite the same as being
-  ** UNIQUE since a UNIQUE column or index can have multiple rows that 
-  ** are NULL and NULL values are equivalent for the purpose of order-distinct.
-  ** To be order-distinct, the columns must be UNIQUE and NOT NULL.
-  **
-  ** The rowid for a table is always UNIQUE and NOT NULL so whenever the
-  ** rowid appears in the ORDER BY clause, the corresponding WhereLoop is
-  ** automatically order-distinct.
-  */
-
-  assert( pOrderBy!=0 );
-
-  /* Sortability of virtual tables is determined by the xBestIndex method
-  ** of the virtual table itself */
-  if( pLast->wsFlags & WHERE_VIRTUALTABLE ){
-    testcase( nLoop>0 );  /* True when outer loops are one-row and match 
-                          ** no ORDER BY terms */
-    return pLast->u.vtab.isOrdered;
-  }
-  if( nLoop && OptimizationDisabled(db, SQLITE_OrderByIdxJoin) ) return 0;
-
-  nOrderBy = pOrderBy->nExpr;
-  testcase( nOrderBy==BMS-1 );
-  if( nOrderBy>BMS-1 ) return 0;  /* Cannot optimize overly large ORDER BYs */
-  isOrderDistinct = 1;
-  obDone = MASKBIT(nOrderBy)-1;
-  orderDistinctMask = 0;
-  ready = 0;
-  for(iLoop=0; isOrderDistinct && obSat<obDone && iLoop<=nLoop; iLoop++){
-    if( iLoop>0 ) ready |= pLoop->maskSelf;
-    pLoop = iLoop<nLoop ? pPath->aLoop[iLoop] : pLast;
-    assert( (pLoop->wsFlags & WHERE_VIRTUALTABLE)==0 );
-    iCur = pWInfo->pTabList->a[pLoop->iTab].iCursor;
-
-    /* Mark off any ORDER BY term X that is a column in the table of
-    ** the current loop for which there is term in the WHERE
-    ** clause of the form X IS NULL or X=? that reference only outer
-    ** loops.
-    */
-    for(i=0; i<nOrderBy; i++){
-      if( MASKBIT(i) & obSat ) continue;
-      pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
-      if( pOBExpr->op!=TK_COLUMN ) continue;
-      if( pOBExpr->iTable!=iCur ) continue;
-      pTerm = findTerm(&pWInfo->sWC, iCur, pOBExpr->iColumn,
-                       ~ready, WO_EQ|WO_ISNULL, 0);
-      if( pTerm==0 ) continue;
-      if( (pTerm->eOperator&WO_EQ)!=0 && pOBExpr->iColumn>=0 ){
-        const char *z1, *z2;
-        pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
-        if( !pColl ) pColl = db->pDfltColl;
-        z1 = pColl->zName;
-        pColl = sqlite3ExprCollSeq(pWInfo->pParse, pTerm->pExpr);
-        if( !pColl ) pColl = db->pDfltColl;
-        z2 = pColl->zName;
-        if( sqlite3StrICmp(z1, z2)!=0 ) continue;
-      }
-      obSat |= MASKBIT(i);
-    }
-
-    if( (pLoop->wsFlags & WHERE_ONEROW)==0 ){
-      if( pLoop->wsFlags & WHERE_IPK ){
-        pIndex = 0;
-        nColumn = 0;
-      }else if( (pIndex = pLoop->u.btree.pIndex)==0 || pIndex->bUnordered ){
-        return 0;
-      }else{
-        nColumn = pIndex->nColumn;
-        isOrderDistinct = pIndex->onError!=OE_None;
-      }
-
-      /* Loop through all columns of the index and deal with the ones
-      ** that are not constrained by == or IN.
-      */
-      rev = revSet = 0;
-      distinctColumns = 0;
-      for(j=0; j<=nColumn; j++){
-        u8 bOnce;   /* True to run the ORDER BY search loop */
-
-        /* Skip over == and IS NULL terms */
-        if( j<pLoop->u.btree.nEq
-         && ((i = pLoop->aLTerm[j]->eOperator) & (WO_EQ|WO_ISNULL))!=0
-        ){
-          if( i & WO_ISNULL ){
-            testcase( isOrderDistinct );
-            isOrderDistinct = 0;
-          }
-          continue;  
-        }
-
-        /* Get the column number in the table (iColumn) and sort order
-        ** (revIdx) for the j-th column of the index.
-        */
-        if( j<nColumn ){
-          /* Normal index columns */
-          iColumn = pIndex->aiColumn[j];
-          revIdx = pIndex->aSortOrder[j];
-          if( iColumn==pIndex->pTable->iPKey ) iColumn = -1;
-        }else{
-          /* The ROWID column at the end */
-          assert( j==nColumn );
-          iColumn = -1;
-          revIdx = 0;
-        }
-
-        /* An unconstrained column that might be NULL means that this
-        ** WhereLoop is not well-ordered 
-        */
-        if( isOrderDistinct
-         && iColumn>=0
-         && j>=pLoop->u.btree.nEq
-         && pIndex->pTable->aCol[iColumn].notNull==0
-        ){
-          isOrderDistinct = 0;
-        }
-
-        /* Find the ORDER BY term that corresponds to the j-th column
-        ** of the index and and mark that ORDER BY term off 
-        */
-        bOnce = 1;
-        isMatch = 0;
-        for(i=0; bOnce && i<nOrderBy; i++){
-          if( MASKBIT(i) & obSat ) continue;
-          pOBExpr = sqlite3ExprSkipCollate(pOrderBy->a[i].pExpr);
-          testcase( wctrlFlags & WHERE_GROUPBY );
-          testcase( wctrlFlags & WHERE_DISTINCTBY );
-          if( (wctrlFlags & (WHERE_GROUPBY|WHERE_DISTINCTBY))==0 ) bOnce = 0;
-          if( pOBExpr->op!=TK_COLUMN ) continue;
-          if( pOBExpr->iTable!=iCur ) continue;
-          if( pOBExpr->iColumn!=iColumn ) continue;
-          if( iColumn>=0 ){
-            pColl = sqlite3ExprCollSeq(pWInfo->pParse, pOrderBy->a[i].pExpr);
-            if( !pColl ) pColl = db->pDfltColl;
-            if( sqlite3StrICmp(pColl->zName, pIndex->azColl[j])!=0 ) continue;
-          }
-          isMatch = 1;
-          break;
-        }
-        if( isMatch ){
-          if( iColumn<0 ){
-            testcase( distinctColumns==0 );
-            distinctColumns = 1;
-          }
-          obSat |= MASKBIT(i);
-          if( (pWInfo->wctrlFlags & WHERE_GROUPBY)==0 ){
-            /* Make sure the sort order is compatible in an ORDER BY clause.
-            ** Sort order is irrelevant for a GROUP BY clause. */
-            if( revSet ){
-              if( (rev ^ revIdx)!=pOrderBy->a[i].sortOrder ) return 0;
-            }else{
-              rev = revIdx ^ pOrderBy->a[i].sortOrder;
-              if( rev ) *pRevMask |= MASKBIT(iLoop);
-              revSet = 1;
-            }
-          }
-        }else{
-          /* No match found */
-          if( j==0 || j<nColumn ){
-            testcase( isOrderDistinct!=0 );
-            isOrderDistinct = 0;
-          }
-          break;
-        }
-      } /* end Loop over all index columns */
-      if( distinctColumns ){
-        testcase( isOrderDistinct==0 );
-        isOrderDistinct = 1;
-      }
-    } /* end-if not one-row */
-
-    /* Mark off any other ORDER BY terms that reference pLoop */
-    if( isOrderDistinct ){
-      orderDistinctMask |= pLoop->maskSelf;
-      for(i=0; i<nOrderBy; i++){
-        Expr *p;
-        if( MASKBIT(i) & obSat ) continue;
-        p = pOrderBy->a[i].pExpr;
-        if( (exprTableUsage(&pWInfo->sMaskSet, p)&~orderDistinctMask)==0 ){
-          obSat |= MASKBIT(i);
-        }
-      }
-    }
-  } /* End the loop over all WhereLoops from outer-most down to inner-most */
-  if( obSat==obDone ) return 1;
-  if( !isOrderDistinct ) return 0;
-  return -1;
-}
-
-#ifdef WHERETRACE_ENABLED
-/* For debugging use only: */
-static const char *wherePathName(WherePath *pPath, int nLoop, WhereLoop *pLast){
-  static char zName[65];
-  int i;
-  for(i=0; i<nLoop; i++){ zName[i] = pPath->aLoop[i]->cId; }
-  if( pLast ) zName[i++] = pLast->cId;
-  zName[i] = 0;
-  return zName;
-}
-#endif
-
-
-/*
-** Given the list of WhereLoop objects at pWInfo->pLoops, this routine
-** attempts to find the lowest cost path that visits each WhereLoop
-** once.  This path is then loaded into the pWInfo->a[].pWLoop fields.
-**
-** Assume that the total number of output rows that will need to be sorted
-** will be nRowEst (in the 10*log2 representation).  Or, ignore sorting
-** costs if nRowEst==0.
-**
-** Return SQLITE_OK on success or SQLITE_NOMEM of a memory allocation
-** error occurs.
-*/
-static int wherePathSolver(WhereInfo *pWInfo, LogEst nRowEst){
-  int mxChoice;             /* Maximum number of simultaneous paths tracked */
-  int nLoop;                /* Number of terms in the join */
-  Parse *pParse;            /* Parsing context */
-  sqlite3 *db;              /* The database connection */
-  int iLoop;                /* Loop counter over the terms of the join */
-  int ii, jj;               /* Loop counters */
-  int mxI = 0;              /* Index of next entry to replace */
-  LogEst rCost;             /* Cost of a path */
-  LogEst nOut;              /* Number of outputs */
-  LogEst mxCost = 0;        /* Maximum cost of a set of paths */
-  LogEst mxOut = 0;         /* Maximum nOut value on the set of paths */
-  LogEst rSortCost;         /* Cost to do a sort */
-  int nTo, nFrom;           /* Number of valid entries in aTo[] and aFrom[] */
-  WherePath *aFrom;         /* All nFrom paths at the previous level */
-  WherePath *aTo;           /* The nTo best paths at the current level */
-  WherePath *pFrom;         /* An element of aFrom[] that we are working on */
-  WherePath *pTo;           /* An element of aTo[] that we are working on */
-  WhereLoop *pWLoop;        /* One of the WhereLoop objects */
-  WhereLoop **pX;           /* Used to divy up the pSpace memory */
-  char *pSpace;             /* Temporary memory used by this routine */
-
-  pParse = pWInfo->pParse;
-  db = pParse->db;
-  nLoop = pWInfo->nLevel;
-  /* TUNING: For simple queries, only the best path is tracked.
-  ** For 2-way joins, the 5 best paths are followed.
-  ** For joins of 3 or more tables, track the 10 best paths */
-  mxChoice = (nLoop==1) ? 1 : (nLoop==2 ? 5 : 10);
-  assert( nLoop<=pWInfo->pTabList->nSrc );
-  WHERETRACE(0x002, ("---- begin solver\n"));
-
-  /* Allocate and initialize space for aTo and aFrom */
-  ii = (sizeof(WherePath)+sizeof(WhereLoop*)*nLoop)*mxChoice*2;
-  pSpace = sqlite3DbMallocRaw(db, ii);
-  if( pSpace==0 ) return SQLITE_NOMEM;
-  aTo = (WherePath*)pSpace;
-  aFrom = aTo+mxChoice;
-  memset(aFrom, 0, sizeof(aFrom[0]));
-  pX = (WhereLoop**)(aFrom+mxChoice);
-  for(ii=mxChoice*2, pFrom=aTo; ii>0; ii--, pFrom++, pX += nLoop){
-    pFrom->aLoop = pX;
-  }
-
-  /* Seed the search with a single WherePath containing zero WhereLoops.
-  **
-  ** TUNING: Do not let the number of iterations go above 25.  If the cost
-  ** of computing an automatic index is not paid back within the first 25
-  ** rows, then do not use the automatic index. */
-  aFrom[0].nRow = MIN(pParse->nQueryLoop, 46);  assert( 46==sqlite3LogEst(25) );
-  nFrom = 1;
-
-  /* Precompute the cost of sorting the final result set, if the caller
-  ** to sqlite3WhereBegin() was concerned about sorting */
-  rSortCost = 0;
-  if( pWInfo->pOrderBy==0 || nRowEst==0 ){
-    aFrom[0].isOrderedValid = 1;
-  }else{
-    /* TUNING: Estimated cost of sorting is 48*N*log2(N) where N is the
-    ** number of output rows. The 48 is the expected size of a row to sort. 
-    ** FIXME:  compute a better estimate of the 48 multiplier based on the
-    ** result set expressions. */
-    rSortCost = nRowEst + estLog(nRowEst);
-    WHERETRACE(0x002,("---- sort cost=%-3d\n", rSortCost));
-  }
-
-  /* Compute successively longer WherePaths using the previous generation
-  ** of WherePaths as the basis for the next.  Keep track of the mxChoice
-  ** best paths at each generation */
-  for(iLoop=0; iLoop<nLoop; iLoop++){
-    nTo = 0;
-    for(ii=0, pFrom=aFrom; ii<nFrom; ii++, pFrom++){
-      for(pWLoop=pWInfo->pLoops; pWLoop; pWLoop=pWLoop->pNextLoop){
-        Bitmask maskNew;
-        Bitmask revMask = 0;
-        u8 isOrderedValid = pFrom->isOrderedValid;
-        u8 isOrdered = pFrom->isOrdered;
-        if( (pWLoop->prereq & ~pFrom->maskLoop)!=0 ) continue;
-        if( (pWLoop->maskSelf & pFrom->maskLoop)!=0 ) continue;
-        /* At this point, pWLoop is a candidate to be the next loop. 
-        ** Compute its cost */
-        rCost = sqlite3LogEstAdd(pWLoop->rSetup,pWLoop->rRun + pFrom->nRow);
-        rCost = sqlite3LogEstAdd(rCost, pFrom->rCost);
-        nOut = pFrom->nRow + pWLoop->nOut;
-        maskNew = pFrom->maskLoop | pWLoop->maskSelf;
-        if( !isOrderedValid ){
-          switch( wherePathSatisfiesOrderBy(pWInfo,
-                       pWInfo->pOrderBy, pFrom, pWInfo->wctrlFlags,
-                       iLoop, pWLoop, &revMask) ){
-            case 1:  /* Yes.  pFrom+pWLoop does satisfy the ORDER BY clause */
-              isOrdered = 1;
-              isOrderedValid = 1;
-              break;
-            case 0:  /* No.  pFrom+pWLoop will require a separate sort */
-              isOrdered = 0;
-              isOrderedValid = 1;
-              rCost = sqlite3LogEstAdd(rCost, rSortCost);
-              break;
-            default: /* Cannot tell yet.  Try again on the next iteration */
-              break;
-          }
-        }else{
-          revMask = pFrom->revLoop;
-        }
-        /* Check to see if pWLoop should be added to the mxChoice best so far */
-        for(jj=0, pTo=aTo; jj<nTo; jj++, pTo++){
-          if( pTo->maskLoop==maskNew
-           && pTo->isOrderedValid==isOrderedValid
-           && ((pTo->rCost<=rCost && pTo->nRow<=nOut) ||
-                (pTo->rCost>=rCost && pTo->nRow>=nOut))
-          ){
-            testcase( jj==nTo-1 );
-            break;
-          }
-        }
-        if( jj>=nTo ){
-          if( nTo>=mxChoice && rCost>=mxCost ){
-#ifdef WHERETRACE_ENABLED
-            if( sqlite3WhereTrace&0x4 ){
-              sqlite3DebugPrintf("Skip   %s cost=%-3d,%3d order=%c\n",
-                  wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
-                  isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
-            }
-#endif
-            continue;
-          }
-          /* Add a new Path to the aTo[] set */
-          if( nTo<mxChoice ){
-            /* Increase the size of the aTo set by one */
-            jj = nTo++;
-          }else{
-            /* New path replaces the prior worst to keep count below mxChoice */
-            jj = mxI;
-          }
-          pTo = &aTo[jj];
-#ifdef WHERETRACE_ENABLED
-          if( sqlite3WhereTrace&0x4 ){
-            sqlite3DebugPrintf("New    %s cost=%-3d,%3d order=%c\n",
-                wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
-                isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
-          }
-#endif
-        }else{
-          if( pTo->rCost<=rCost && pTo->nRow<=nOut ){
-#ifdef WHERETRACE_ENABLED
-            if( sqlite3WhereTrace&0x4 ){
-              sqlite3DebugPrintf(
-                  "Skip   %s cost=%-3d,%3d order=%c",
-                  wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
-                  isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
-              sqlite3DebugPrintf("   vs %s cost=%-3d,%d order=%c\n",
-                  wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
-                  pTo->isOrderedValid ? (pTo->isOrdered ? 'Y' : 'N') : '?');
-            }
-#endif
-            testcase( pTo->rCost==rCost );
-            continue;
-          }
-          testcase( pTo->rCost==rCost+1 );
-          /* A new and better score for a previously created equivalent path */
-#ifdef WHERETRACE_ENABLED
-          if( sqlite3WhereTrace&0x4 ){
-            sqlite3DebugPrintf(
-                "Update %s cost=%-3d,%3d order=%c",
-                wherePathName(pFrom, iLoop, pWLoop), rCost, nOut,
-                isOrderedValid ? (isOrdered ? 'Y' : 'N') : '?');
-            sqlite3DebugPrintf("  was %s cost=%-3d,%3d order=%c\n",
-                wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
-                pTo->isOrderedValid ? (pTo->isOrdered ? 'Y' : 'N') : '?');
-          }
-#endif
-        }
-        /* pWLoop is a winner.  Add it to the set of best so far */
-        pTo->maskLoop = pFrom->maskLoop | pWLoop->maskSelf;
-        pTo->revLoop = revMask;
-        pTo->nRow = nOut;
-        pTo->rCost = rCost;
-        pTo->isOrderedValid = isOrderedValid;
-        pTo->isOrdered = isOrdered;
-        memcpy(pTo->aLoop, pFrom->aLoop, sizeof(WhereLoop*)*iLoop);
-        pTo->aLoop[iLoop] = pWLoop;
-        if( nTo>=mxChoice ){
-          mxI = 0;
-          mxCost = aTo[0].rCost;
-          mxOut = aTo[0].nRow;
-          for(jj=1, pTo=&aTo[1]; jj<mxChoice; jj++, pTo++){
-            if( pTo->rCost>mxCost || (pTo->rCost==mxCost && pTo->nRow>mxOut) ){
-              mxCost = pTo->rCost;
-              mxOut = pTo->nRow;
-              mxI = jj;
-            }
-          }
-        }
-      }
-    }
-
-#ifdef WHERETRACE_ENABLED
-    if( sqlite3WhereTrace>=2 ){
-      sqlite3DebugPrintf("---- after round %d ----\n", iLoop);
-      for(ii=0, pTo=aTo; ii<nTo; ii++, pTo++){
-        sqlite3DebugPrintf(" %s cost=%-3d nrow=%-3d order=%c",
-           wherePathName(pTo, iLoop+1, 0), pTo->rCost, pTo->nRow,
-           pTo->isOrderedValid ? (pTo->isOrdered ? 'Y' : 'N') : '?');
-        if( pTo->isOrderedValid && pTo->isOrdered ){
-          sqlite3DebugPrintf(" rev=0x%llx\n", pTo->revLoop);
-        }else{
-          sqlite3DebugPrintf("\n");
-        }
-      }
-    }
-#endif
-
-    /* Swap the roles of aFrom and aTo for the next generation */
-    pFrom = aTo;
-    aTo = aFrom;
-    aFrom = pFrom;
-    nFrom = nTo;
-  }
-
-  if( nFrom==0 ){
-    sqlite3ErrorMsg(pParse, "no query solution");
-    sqlite3DbFree(db, pSpace);
-    return SQLITE_ERROR;
-  }
-  
-  /* Find the lowest cost path.  pFrom will be left pointing to that path */
-  pFrom = aFrom;
-  for(ii=1; ii<nFrom; ii++){
-    if( pFrom->rCost>aFrom[ii].rCost ) pFrom = &aFrom[ii];
-  }
-  assert( pWInfo->nLevel==nLoop );
-  /* Load the lowest cost path into pWInfo */
-  for(iLoop=0; iLoop<nLoop; iLoop++){
-    WhereLevel *pLevel = pWInfo->a + iLoop;
-    pLevel->pWLoop = pWLoop = pFrom->aLoop[iLoop];
-    pLevel->iFrom = pWLoop->iTab;
-    pLevel->iTabCur = pWInfo->pTabList->a[pLevel->iFrom].iCursor;
-  }
-  if( (pWInfo->wctrlFlags & WHERE_WANT_DISTINCT)!=0
-   && (pWInfo->wctrlFlags & WHERE_DISTINCTBY)==0
-   && pWInfo->eDistinct==WHERE_DISTINCT_NOOP
-   && nRowEst
-  ){
-    Bitmask notUsed;
-    int rc = wherePathSatisfiesOrderBy(pWInfo, pWInfo->pResultSet, pFrom,
-                 WHERE_DISTINCTBY, nLoop-1, pFrom->aLoop[nLoop-1], &notUsed);
-    if( rc==1 ) pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
-  }
-  if( pFrom->isOrdered ){
-    if( pWInfo->wctrlFlags & WHERE_DISTINCTBY ){
-      pWInfo->eDistinct = WHERE_DISTINCT_ORDERED;
-    }else{
-      pWInfo->bOBSat = 1;
-      pWInfo->revMask = pFrom->revLoop;
-    }
-  }
-  pWInfo->nRowOut = pFrom->nRow;
-
-  /* Free temporary memory and return success */
-  sqlite3DbFree(db, pSpace);
-  return SQLITE_OK;
-}
-
-/*
-** Most queries use only a single table (they are not joins) and have
-** simple == constraints against indexed fields.  This routine attempts
-** to plan those simple cases using much less ceremony than the
-** general-purpose query planner, and thereby yield faster sqlite3_prepare()
-** times for the common case.
-**
-** Return non-zero on success, if this query can be handled by this
-** no-frills query planner.  Return zero if this query needs the 
-** general-purpose query planner.
-*/
-static int whereShortCut(WhereLoopBuilder *pBuilder){
-  WhereInfo *pWInfo;
-  struct SrcList_item *pItem;
-  WhereClause *pWC;
-  WhereTerm *pTerm;
-  WhereLoop *pLoop;
-  int iCur;
-  int j;
-  Table *pTab;
-  Index *pIdx;
-  
-  pWInfo = pBuilder->pWInfo;
-  if( pWInfo->wctrlFlags & WHERE_FORCE_TABLE ) return 0;
-  assert( pWInfo->pTabList->nSrc>=1 );
-  pItem = pWInfo->pTabList->a;
-  pTab = pItem->pTab;
-  if( IsVirtual(pTab) ) return 0;
-  if( pItem->zIndex ) return 0;
-  iCur = pItem->iCursor;
-  pWC = &pWInfo->sWC;
-  pLoop = pBuilder->pNew;
-  pLoop->wsFlags = 0;
-  pTerm = findTerm(pWC, iCur, -1, 0, WO_EQ, 0);
-  if( pTerm ){
-    pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_IPK|WHERE_ONEROW;
-    pLoop->aLTerm[0] = pTerm;
-    pLoop->nLTerm = 1;
-    pLoop->u.btree.nEq = 1;
-    /* TUNING: Cost of a rowid lookup is 10 */
-    pLoop->rRun = 33;  /* 33==sqlite3LogEst(10) */
-  }else{
-    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
-      assert( pLoop->aLTermSpace==pLoop->aLTerm );
-      assert( ArraySize(pLoop->aLTermSpace)==4 );
-      if( pIdx->onError==OE_None 
-       || pIdx->pPartIdxWhere!=0 
-       || pIdx->nColumn>ArraySize(pLoop->aLTermSpace) 
-      ) continue;
-      for(j=0; j<pIdx->nColumn; j++){
-        pTerm = findTerm(pWC, iCur, pIdx->aiColumn[j], 0, WO_EQ, pIdx);
-        if( pTerm==0 ) break;
-        pLoop->aLTerm[j] = pTerm;
-      }
-      if( j!=pIdx->nColumn ) continue;
-      pLoop->wsFlags = WHERE_COLUMN_EQ|WHERE_ONEROW|WHERE_INDEXED;
-      if( (pItem->colUsed & ~columnsInIndex(pIdx))==0 ){
-        pLoop->wsFlags |= WHERE_IDX_ONLY;
-      }
-      pLoop->nLTerm = j;
-      pLoop->u.btree.nEq = j;
-      pLoop->u.btree.pIndex = pIdx;
-      /* TUNING: Cost of a unique index lookup is 15 */
-      pLoop->rRun = 39;  /* 39==sqlite3LogEst(15) */
-      break;
-    }
-  }
-  if( pLoop->wsFlags ){
-    pLoop->nOut = (LogEst)1;
-    pWInfo->a[0].pWLoop = pLoop;
-    pLoop->maskSelf = getMask(&pWInfo->sMaskSet, iCur);
-    pWInfo->a[0].iTabCur = iCur;
-    pWInfo->nRowOut = 1;
-    if( pWInfo->pOrderBy ) pWInfo->bOBSat =  1;
-    if( pWInfo->wctrlFlags & WHERE_WANT_DISTINCT ){
-      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
-    }
-#ifdef SQLITE_DEBUG
-    pLoop->cId = '0';
-#endif
-    return 1;
-  }
-  return 0;
-}
-
-/*
-** Generate the beginning of the loop used for WHERE clause processing.
-** The return value is a pointer to an opaque structure that contains
-** information needed to terminate the loop.  Later, the calling routine
-** should invoke sqlite3WhereEnd() with the return value of this function
-** in order to complete the WHERE clause processing.
-**
-** If an error occurs, this routine returns NULL.
-**
-** The basic idea is to do a nested loop, one loop for each table in
-** the FROM clause of a select.  (INSERT and UPDATE statements are the
-** same as a SELECT with only a single table in the FROM clause.)  For
-** example, if the SQL is this:
-**
-**       SELECT * FROM t1, t2, t3 WHERE ...;
-**
-** Then the code generated is conceptually like the following:
-**
-**      foreach row1 in t1 do       \    Code generated
-**        foreach row2 in t2 do      |-- by sqlite3WhereBegin()
-**          foreach row3 in t3 do   /
-**            ...
-**          end                     \    Code generated
-**        end                        |-- by sqlite3WhereEnd()
-**      end                         /
-**
-** Note that the loops might not be nested in the order in which they
-** appear in the FROM clause if a different order is better able to make
-** use of indices.  Note also that when the IN operator appears in
-** the WHERE clause, it might result in additional nested loops for
-** scanning through all values on the right-hand side of the IN.
-**
-** There are Btree cursors associated with each table.  t1 uses cursor
-** number pTabList->a[0].iCursor.  t2 uses the cursor pTabList->a[1].iCursor.
-** And so forth.  This routine generates code to open those VDBE cursors
-** and sqlite3WhereEnd() generates the code to close them.
-**
-** The code that sqlite3WhereBegin() generates leaves the cursors named
-** in pTabList pointing at their appropriate entries.  The [...] code
-** can use OP_Column and OP_Rowid opcodes on these cursors to extract
-** data from the various tables of the loop.
-**
-** If the WHERE clause is empty, the foreach loops must each scan their
-** entire tables.  Thus a three-way join is an O(N^3) operation.  But if
-** the tables have indices and there are terms in the WHERE clause that
-** refer to those indices, a complete table scan can be avoided and the
-** code will run much faster.  Most of the work of this routine is checking
-** to see if there are indices that can be used to speed up the loop.
-**
-** Terms of the WHERE clause are also used to limit which rows actually
-** make it to the "..." in the middle of the loop.  After each "foreach",
-** terms of the WHERE clause that use only terms in that loop and outer
-** loops are evaluated and if false a jump is made around all subsequent
-** inner loops (or around the "..." if the test occurs within the inner-
-** most loop)
-**
-** OUTER JOINS
-**
-** An outer join of tables t1 and t2 is conceptally coded as follows:
-**
-**    foreach row1 in t1 do
-**      flag = 0
-**      foreach row2 in t2 do
-**        start:
-**          ...
-**          flag = 1
-**      end
-**      if flag==0 then
-**        move the row2 cursor to a null row
-**        goto start
-**      fi
-**    end
-**
-** ORDER BY CLAUSE PROCESSING
-**
-** pOrderBy is a pointer to the ORDER BY clause (or the GROUP BY clause
-** if the WHERE_GROUPBY flag is set in wctrlFlags) of a SELECT statement
-** if there is one.  If there is no ORDER BY clause or if this routine
-** is called from an UPDATE or DELETE statement, then pOrderBy is NULL.
-*/
-WhereInfo *sqlite3WhereBegin(
-  Parse *pParse,        /* The parser context */
-  SrcList *pTabList,    /* FROM clause: A list of all tables to be scanned */
-  Expr *pWhere,         /* The WHERE clause */
-  ExprList *pOrderBy,   /* An ORDER BY clause, or NULL */
-  ExprList *pResultSet, /* Result set of the query */
-  u16 wctrlFlags,       /* One of the WHERE_* flags defined in sqliteInt.h */
-  int iIdxCur           /* If WHERE_ONETABLE_ONLY is set, index cursor number */
-){
-  int nByteWInfo;            /* Num. bytes allocated for WhereInfo struct */
-  int nTabList;              /* Number of elements in pTabList */
-  WhereInfo *pWInfo;         /* Will become the return value of this function */
-  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
-  Bitmask notReady;          /* Cursors that are not yet positioned */
-  WhereLoopBuilder sWLB;     /* The WhereLoop builder */
-  WhereMaskSet *pMaskSet;    /* The expression mask set */
-  WhereLevel *pLevel;        /* A single level in pWInfo->a[] */
-  WhereLoop *pLoop;          /* Pointer to a single WhereLoop object */
-  int ii;                    /* Loop counter */
-  sqlite3 *db;               /* Database connection */
-  int rc;                    /* Return code */
-
-
-  /* Variable initialization */
-  db = pParse->db;
-  memset(&sWLB, 0, sizeof(sWLB));
-  sWLB.pOrderBy = pOrderBy;
-
-  /* Disable the DISTINCT optimization if SQLITE_DistinctOpt is set via
-  ** sqlite3_test_ctrl(SQLITE_TESTCTRL_OPTIMIZATIONS,...) */
-  if( OptimizationDisabled(db, SQLITE_DistinctOpt) ){
-    wctrlFlags &= ~WHERE_WANT_DISTINCT;
-  }
-
-  /* The number of tables in the FROM clause is limited by the number of
-  ** bits in a Bitmask 
-  */
-  testcase( pTabList->nSrc==BMS );
-  if( pTabList->nSrc>BMS ){
-    sqlite3ErrorMsg(pParse, "at most %d tables in a join", BMS);
-    return 0;
-  }
-
-  /* This function normally generates a nested loop for all tables in 
-  ** pTabList.  But if the WHERE_ONETABLE_ONLY flag is set, then we should
-  ** only generate code for the first table in pTabList and assume that
-  ** any cursors associated with subsequent tables are uninitialized.
-  */
-  nTabList = (wctrlFlags & WHERE_ONETABLE_ONLY) ? 1 : pTabList->nSrc;
-
-  /* Allocate and initialize the WhereInfo structure that will become the
-  ** return value. A single allocation is used to store the WhereInfo
-  ** struct, the contents of WhereInfo.a[], the WhereClause structure
-  ** and the WhereMaskSet structure. Since WhereClause contains an 8-byte
-  ** field (type Bitmask) it must be aligned on an 8-byte boundary on
-  ** some architectures. Hence the ROUND8() below.
-  */
-  nByteWInfo = ROUND8(sizeof(WhereInfo)+(nTabList-1)*sizeof(WhereLevel));
-  pWInfo = sqlite3DbMallocZero(db, nByteWInfo + sizeof(WhereLoop));
-  if( db->mallocFailed ){
-    sqlite3DbFree(db, pWInfo);
-    pWInfo = 0;
-    goto whereBeginError;
-  }
-  pWInfo->nLevel = nTabList;
-  pWInfo->pParse = pParse;
-  pWInfo->pTabList = pTabList;
-  pWInfo->pOrderBy = pOrderBy;
-  pWInfo->pResultSet = pResultSet;
-  pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
-  pWInfo->wctrlFlags = wctrlFlags;
-  pWInfo->savedNQueryLoop = pParse->nQueryLoop;
-  pMaskSet = &pWInfo->sMaskSet;
-  sWLB.pWInfo = pWInfo;
-  sWLB.pWC = &pWInfo->sWC;
-  sWLB.pNew = (WhereLoop*)(((char*)pWInfo)+nByteWInfo);
-  assert( EIGHT_BYTE_ALIGNMENT(sWLB.pNew) );
-  whereLoopInit(sWLB.pNew);
-#ifdef SQLITE_DEBUG
-  sWLB.pNew->cId = '*';
-#endif
-
-  /* Split the WHERE clause into separate subexpressions where each
-  ** subexpression is separated by an AND operator.
-  */
-  initMaskSet(pMaskSet);
-  whereClauseInit(&pWInfo->sWC, pWInfo);
-  sqlite3ExprCodeConstants(pParse, pWhere);
-  whereSplit(&pWInfo->sWC, pWhere, TK_AND);
-  sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */
-    
-  /* Special case: a WHERE clause that is constant.  Evaluate the
-  ** expression and either jump over all of the code or fall thru.
-  */
-  if( pWhere && (nTabList==0 || sqlite3ExprIsConstantNotJoin(pWhere)) ){
-    sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, SQLITE_JUMPIFNULL);
-    pWhere = 0;
-  }
-
-  /* Special case: No FROM clause
-  */
-  if( nTabList==0 ){
-    if( pOrderBy ) pWInfo->bOBSat = 1;
-    if( wctrlFlags & WHERE_WANT_DISTINCT ){
-      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
-    }
-  }
-
-  /* Assign a bit from the bitmask to every term in the FROM clause.
-  **
-  ** When assigning bitmask values to FROM clause cursors, it must be
-  ** the case that if X is the bitmask for the N-th FROM clause term then
-  ** the bitmask for all FROM clause terms to the left of the N-th term
-  ** is (X-1).   An expression from the ON clause of a LEFT JOIN can use
-  ** its Expr.iRightJoinTable value to find the bitmask of the right table
-  ** of the join.  Subtracting one from the right table bitmask gives a
-  ** bitmask for all tables to the left of the join.  Knowing the bitmask
-  ** for all tables to the left of a left join is important.  Ticket #3015.
-  **
-  ** Note that bitmasks are created for all pTabList->nSrc tables in
-  ** pTabList, not just the first nTabList tables.  nTabList is normally
-  ** equal to pTabList->nSrc but might be shortened to 1 if the
-  ** WHERE_ONETABLE_ONLY flag is set.
-  */
-  for(ii=0; ii<pTabList->nSrc; ii++){
-    createMask(pMaskSet, pTabList->a[ii].iCursor);
-  }
-#ifndef NDEBUG
-  {
-    Bitmask toTheLeft = 0;
-    for(ii=0; ii<pTabList->nSrc; ii++){
-      Bitmask m = getMask(pMaskSet, pTabList->a[ii].iCursor);
-      assert( (m-1)==toTheLeft );
-      toTheLeft |= m;
-    }
-  }
-#endif
-
-  /* Analyze all of the subexpressions.  Note that exprAnalyze() might
-  ** add new virtual terms onto the end of the WHERE clause.  We do not
-  ** want to analyze these virtual terms, so start analyzing at the end
-  ** and work forward so that the added virtual terms are never processed.
-  */
-  exprAnalyzeAll(pTabList, &pWInfo->sWC);
-  if( db->mallocFailed ){
-    goto whereBeginError;
-  }
-
-  /* If the ORDER BY (or GROUP BY) clause contains references to general
-  ** expressions, then we won't be able to satisfy it using indices, so
-  ** go ahead and disable it now.
-  */
-  if( pOrderBy && (wctrlFlags & WHERE_WANT_DISTINCT)!=0 ){
-    for(ii=0; ii<pOrderBy->nExpr; ii++){
-      Expr *pExpr = sqlite3ExprSkipCollate(pOrderBy->a[ii].pExpr);
-      if( pExpr->op!=TK_COLUMN ){
-        pWInfo->pOrderBy = pOrderBy = 0;
-        break;
-      }else if( pExpr->iColumn<0 ){
-        break;
-      }
-    }
-  }
-
-  if( wctrlFlags & WHERE_WANT_DISTINCT ){
-    if( isDistinctRedundant(pParse, pTabList, &pWInfo->sWC, pResultSet) ){
-      /* The DISTINCT marking is pointless.  Ignore it. */
-      pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
-    }else if( pOrderBy==0 ){
-      /* Try to ORDER BY the result set to make distinct processing easier */
-      pWInfo->wctrlFlags |= WHERE_DISTINCTBY;
-      pWInfo->pOrderBy = pResultSet;
-    }
-  }
-
-  /* Construct the WhereLoop objects */
-  WHERETRACE(0xffff,("*** Optimizer Start ***\n"));
-  if( nTabList!=1 || whereShortCut(&sWLB)==0 ){
-    rc = whereLoopAddAll(&sWLB);
-    if( rc ) goto whereBeginError;
-  
-    /* Display all of the WhereLoop objects if wheretrace is enabled */
-#ifdef WHERETRACE_ENABLED
-    if( sqlite3WhereTrace ){
-      WhereLoop *p;
-      int i;
-      static char zLabel[] = "0123456789abcdefghijklmnopqrstuvwyxz"
-                                       "ABCDEFGHIJKLMNOPQRSTUVWYXZ";
-      for(p=pWInfo->pLoops, i=0; p; p=p->pNextLoop, i++){
-        p->cId = zLabel[i%sizeof(zLabel)];
-        whereLoopPrint(p, pTabList);
-      }
-    }
-#endif
-  
-    wherePathSolver(pWInfo, 0);
-    if( db->mallocFailed ) goto whereBeginError;
-    if( pWInfo->pOrderBy ){
-       wherePathSolver(pWInfo, pWInfo->nRowOut+1);
-       if( db->mallocFailed ) goto whereBeginError;
-    }
-  }
-  if( pWInfo->pOrderBy==0 && (db->flags & SQLITE_ReverseOrder)!=0 ){
-     pWInfo->revMask = (Bitmask)(-1);
-  }
-  if( pParse->nErr || NEVER(db->mallocFailed) ){
-    goto whereBeginError;
-  }
-#ifdef WHERETRACE_ENABLED
-  if( sqlite3WhereTrace ){
-    int ii;
-    sqlite3DebugPrintf("---- Solution nRow=%d", pWInfo->nRowOut);
-    if( pWInfo->bOBSat ){
-      sqlite3DebugPrintf(" ORDERBY=0x%llx", pWInfo->revMask);
-    }
-    switch( pWInfo->eDistinct ){
-      case WHERE_DISTINCT_UNIQUE: {
-        sqlite3DebugPrintf("  DISTINCT=unique");
-        break;
-      }
-      case WHERE_DISTINCT_ORDERED: {
-        sqlite3DebugPrintf("  DISTINCT=ordered");
-        break;
-      }
-      case WHERE_DISTINCT_UNORDERED: {
-        sqlite3DebugPrintf("  DISTINCT=unordered");
-        break;
-      }
-    }
-    sqlite3DebugPrintf("\n");
-    for(ii=0; ii<pWInfo->nLevel; ii++){
-      whereLoopPrint(pWInfo->a[ii].pWLoop, pTabList);
-    }
-  }
-#endif
-  /* Attempt to omit tables from the join that do not effect the result */
-  if( pWInfo->nLevel>=2
-   && pResultSet!=0
-   && OptimizationEnabled(db, SQLITE_OmitNoopJoin)
-  ){
-    Bitmask tabUsed = exprListTableUsage(pMaskSet, pResultSet);
-    if( sWLB.pOrderBy ) tabUsed |= exprListTableUsage(pMaskSet, sWLB.pOrderBy);
-    while( pWInfo->nLevel>=2 ){
-      WhereTerm *pTerm, *pEnd;
-      pLoop = pWInfo->a[pWInfo->nLevel-1].pWLoop;
-      if( (pWInfo->pTabList->a[pLoop->iTab].jointype & JT_LEFT)==0 ) break;
-      if( (wctrlFlags & WHERE_WANT_DISTINCT)==0
-       && (pLoop->wsFlags & WHERE_ONEROW)==0
-      ){
-        break;
-      }
-      if( (tabUsed & pLoop->maskSelf)!=0 ) break;
-      pEnd = sWLB.pWC->a + sWLB.pWC->nTerm;
-      for(pTerm=sWLB.pWC->a; pTerm<pEnd; pTerm++){
-        if( (pTerm->prereqAll & pLoop->maskSelf)!=0
-         && !ExprHasProperty(pTerm->pExpr, EP_FromJoin)
-        ){
-          break;
-        }
-      }
-      if( pTerm<pEnd ) break;
-      WHERETRACE(0xffff, ("-> drop loop %c not used\n", pLoop->cId));
-      pWInfo->nLevel--;
-      nTabList--;
-    }
-  }
-  WHERETRACE(0xffff,("*** Optimizer Finished ***\n"));
-  pWInfo->pParse->nQueryLoop += pWInfo->nRowOut;
-
-  /* If the caller is an UPDATE or DELETE statement that is requesting
-  ** to use a one-pass algorithm, determine if this is appropriate.
-  ** The one-pass algorithm only works if the WHERE clause constrains
-  ** the statement to update a single row.
-  */
-  assert( (wctrlFlags & WHERE_ONEPASS_DESIRED)==0 || pWInfo->nLevel==1 );
-  if( (wctrlFlags & WHERE_ONEPASS_DESIRED)!=0 
-   && (pWInfo->a[0].pWLoop->wsFlags & WHERE_ONEROW)!=0 ){
-    pWInfo->okOnePass = 1;
-    pWInfo->a[0].pWLoop->wsFlags &= ~WHERE_IDX_ONLY;
-  }
-
-  /* Open all tables in the pTabList and any indices selected for
-  ** searching those tables.
-  */
-  notReady = ~(Bitmask)0;
-  for(ii=0, pLevel=pWInfo->a; ii<nTabList; ii++, pLevel++){
-    Table *pTab;     /* Table to open */
-    int iDb;         /* Index of database containing table/index */
-    struct SrcList_item *pTabItem;
-
-    pTabItem = &pTabList->a[pLevel->iFrom];
-    pTab = pTabItem->pTab;
-    iDb = sqlite3SchemaToIndex(db, pTab->pSchema);
-    pLoop = pLevel->pWLoop;
-    if( (pTab->tabFlags & TF_Ephemeral)!=0 || pTab->pSelect ){
-      /* Do nothing */
-    }else
-#ifndef SQLITE_OMIT_VIRTUALTABLE
-    if( (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 ){
-      const char *pVTab = (const char *)sqlite3GetVTable(db, pTab);
-      int iCur = pTabItem->iCursor;
-      sqlite3VdbeAddOp4(v, OP_VOpen, iCur, 0, 0, pVTab, P4_VTAB);
-    }else if( IsVirtual(pTab) ){
-      /* noop */
-    }else
-#endif
-    if( (pLoop->wsFlags & WHERE_IDX_ONLY)==0
-         && (wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0 ){
-      int op = pWInfo->okOnePass ? OP_OpenWrite : OP_OpenRead;
-      sqlite3OpenTable(pParse, pTabItem->iCursor, iDb, pTab, op);
-      testcase( !pWInfo->okOnePass && pTab->nCol==BMS-1 );
-      testcase( !pWInfo->okOnePass && pTab->nCol==BMS );
-      if( !pWInfo->okOnePass && pTab->nCol<BMS ){
-        Bitmask b = pTabItem->colUsed;
-        int n = 0;
-        for(; b; b=b>>1, n++){}
-        sqlite3VdbeChangeP4(v, sqlite3VdbeCurrentAddr(v)-1, 
-                            SQLITE_INT_TO_PTR(n), P4_INT32);
-        assert( n<=pTab->nCol );
-      }
-    }else{
-      sqlite3TableLock(pParse, iDb, pTab->tnum, 0, pTab->zName);
-    }
-    if( pLoop->wsFlags & WHERE_INDEXED ){
-      Index *pIx = pLoop->u.btree.pIndex;
-      KeyInfo *pKey = sqlite3IndexKeyinfo(pParse, pIx);
-      /* FIXME:  As an optimization use pTabItem->iCursor if WHERE_IDX_ONLY */
-      int iIndexCur = pLevel->iIdxCur = iIdxCur ? iIdxCur : pParse->nTab++;
-      assert( pIx->pSchema==pTab->pSchema );
-      assert( iIndexCur>=0 );
-      sqlite3VdbeAddOp4(v, OP_OpenRead, iIndexCur, pIx->tnum, iDb,
-                        (char*)pKey, P4_KEYINFO_HANDOFF);
-      VdbeComment((v, "%s", pIx->zName));
-    }
-    sqlite3CodeVerifySchema(pParse, iDb);
-    notReady &= ~getMask(&pWInfo->sMaskSet, pTabItem->iCursor);
-  }
-  pWInfo->iTop = sqlite3VdbeCurrentAddr(v);
-  if( db->mallocFailed ) goto whereBeginError;
-
-  /* Generate the code to do the search.  Each iteration of the for
-  ** loop below generates code for a single nested loop of the VM
-  ** program.
-  */
-  notReady = ~(Bitmask)0;
-  for(ii=0; ii<nTabList; ii++){
-    pLevel = &pWInfo->a[ii];
-#ifndef SQLITE_OMIT_AUTOMATIC_INDEX
-    if( (pLevel->pWLoop->wsFlags & WHERE_AUTO_INDEX)!=0 ){
-      constructAutomaticIndex(pParse, &pWInfo->sWC,
-                &pTabList->a[pLevel->iFrom], notReady, pLevel);
-      if( db->mallocFailed ) goto whereBeginError;
-    }
-#endif
-    explainOneScan(pParse, pTabList, pLevel, ii, pLevel->iFrom, wctrlFlags);
-    pLevel->addrBody = sqlite3VdbeCurrentAddr(v);
-    notReady = codeOneLoopStart(pWInfo, ii, notReady);
-    pWInfo->iContinue = pLevel->addrCont;
-  }
-
-  /* Done. */
-  return pWInfo;
-
-  /* Jump here if malloc fails */
-whereBeginError:
-  if( pWInfo ){
-    pParse->nQueryLoop = pWInfo->savedNQueryLoop;
-    whereInfoFree(db, pWInfo);
-  }
-  return 0;
-}
-
-/*
-** Generate the end of the WHERE loop.  See comments on 
-** sqlite3WhereBegin() for additional information.
-*/
-void sqlite3WhereEnd(WhereInfo *pWInfo){
-  Parse *pParse = pWInfo->pParse;
-  Vdbe *v = pParse->pVdbe;
-  int i;
-  WhereLevel *pLevel;
-  WhereLoop *pLoop;
-  SrcList *pTabList = pWInfo->pTabList;
-  sqlite3 *db = pParse->db;
-
-  /* Generate loop termination code.
-  */
-  sqlite3ExprCacheClear(pParse);
-  for(i=pWInfo->nLevel-1; i>=0; i--){
-    pLevel = &pWInfo->a[i];
-    pLoop = pLevel->pWLoop;
-    sqlite3VdbeResolveLabel(v, pLevel->addrCont);
-    if( pLevel->op!=OP_Noop ){
-      sqlite3VdbeAddOp2(v, pLevel->op, pLevel->p1, pLevel->p2);
-      sqlite3VdbeChangeP5(v, pLevel->p5);
-    }
-    if( pLoop->wsFlags & WHERE_IN_ABLE && pLevel->u.in.nIn>0 ){
-      struct InLoop *pIn;
-      int j;
-      sqlite3VdbeResolveLabel(v, pLevel->addrNxt);
-      for(j=pLevel->u.in.nIn, pIn=&pLevel->u.in.aInLoop[j-1]; j>0; j--, pIn--){
-        sqlite3VdbeJumpHere(v, pIn->addrInTop+1);
-        sqlite3VdbeAddOp2(v, pIn->eEndLoopOp, pIn->iCur, pIn->addrInTop);
-        sqlite3VdbeJumpHere(v, pIn->addrInTop-1);
-      }
-      sqlite3DbFree(db, pLevel->u.in.aInLoop);
-    }
-    sqlite3VdbeResolveLabel(v, pLevel->addrBrk);
-    if( pLevel->iLeftJoin ){
-      int addr;
-      addr = sqlite3VdbeAddOp1(v, OP_IfPos, pLevel->iLeftJoin);
-      assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0
-           || (pLoop->wsFlags & WHERE_INDEXED)!=0 );
-      if( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 ){
-        sqlite3VdbeAddOp1(v, OP_NullRow, pTabList->a[i].iCursor);
-      }
-      if( pLoop->wsFlags & WHERE_INDEXED ){
-        sqlite3VdbeAddOp1(v, OP_NullRow, pLevel->iIdxCur);
-      }
-      if( pLevel->op==OP_Return ){
-        sqlite3VdbeAddOp2(v, OP_Gosub, pLevel->p1, pLevel->addrFirst);
-      }else{
-        sqlite3VdbeAddOp2(v, OP_Goto, 0, pLevel->addrFirst);
-      }
-      sqlite3VdbeJumpHere(v, addr);
-    }
-  }
-
-  /* The "break" point is here, just past the end of the outer loop.
-  ** Set it.
-  */
-  sqlite3VdbeResolveLabel(v, pWInfo->iBreak);
-
-  /* Close all of the cursors that were opened by sqlite3WhereBegin.
-  */
-  assert( pWInfo->nLevel<=pTabList->nSrc );
-  for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){
-    Index *pIdx = 0;
-    struct SrcList_item *pTabItem = &pTabList->a[pLevel->iFrom];
-    Table *pTab = pTabItem->pTab;
-    assert( pTab!=0 );
-    pLoop = pLevel->pWLoop;
-    if( (pTab->tabFlags & TF_Ephemeral)==0
-     && pTab->pSelect==0
-     && (pWInfo->wctrlFlags & WHERE_OMIT_OPEN_CLOSE)==0
-    ){
-      int ws = pLoop->wsFlags;
-      if( !pWInfo->okOnePass && (ws & WHERE_IDX_ONLY)==0 ){
-        sqlite3VdbeAddOp1(v, OP_Close, pTabItem->iCursor);
-      }
-      if( (ws & WHERE_INDEXED)!=0 && (ws & (WHERE_IPK|WHERE_AUTO_INDEX))==0 ){
-        sqlite3VdbeAddOp1(v, OP_Close, pLevel->iIdxCur);
-      }
-    }
-
-    /* If this scan uses an index, make VDBE code substitutions to read data
-    ** from the index instead of from the table where possible.  In some cases
-    ** this optimization prevents the table from ever being read, which can
-    ** yield a significant performance boost.
-    ** 
-    ** Calls to the code generator in between sqlite3WhereBegin and
-    ** sqlite3WhereEnd will have created code that references the table
-    ** directly.  This loop scans all that code looking for opcodes
-    ** that reference the table and converts them into opcodes that
-    ** reference the index.
-    */
-    if( pLoop->wsFlags & (WHERE_INDEXED|WHERE_IDX_ONLY) ){
-      pIdx = pLoop->u.btree.pIndex;
-    }else if( pLoop->wsFlags & WHERE_MULTI_OR ){
-      pIdx = pLevel->u.pCovidx;
-    }
-    if( pIdx && !db->mallocFailed ){
-      int k, j, last;
-      VdbeOp *pOp;
-
-      last = sqlite3VdbeCurrentAddr(v);
-      k = pLevel->addrBody;
-      pOp = sqlite3VdbeGetOp(v, k);
-      for(; k<last; k++, pOp++){
-        if( pOp->p1!=pLevel->iTabCur ) continue;
-        if( pOp->opcode==OP_Column ){
-          for(j=0; j<pIdx->nColumn; j++){
-            if( pOp->p2==pIdx->aiColumn[j] ){
-              pOp->p2 = j;
-              pOp->p1 = pLevel->iIdxCur;
-              break;
-            }
-          }
-          assert( (pLoop->wsFlags & WHERE_IDX_ONLY)==0 || j<pIdx->nColumn );
-        }else if( pOp->opcode==OP_Rowid ){
-          pOp->p1 = pLevel->iIdxCur;
-          pOp->opcode = OP_IdxRowid;
-        }
-      }
-    }
-  }
-
-  /* Final cleanup
-  */
-  pParse->nQueryLoop = pWInfo->savedNQueryLoop;
-  whereInfoFree(db, pWInfo);
-  return;
-}