Copy the KDE 3.5 branch to branches/trinity for new KDE 3.5 features.

BUG:215923


git-svn-id: svn://anonsvn.kde.org/home/kde/branches/trinity/kdenetwork@1054174 283d02a7-25f6-0310-bc7c-ecb5cbfe19da

1 files changed, 1210 insertions, 0 deletions

diff --git a/kopete/plugins/statistics/sqlite/where.c b/kopete/plugins/statistics/sqlite/where.c
new file mode 100644
index 00000000..08c174e9
--- /dev/null
+++ b/kopete/plugins/statistics/sqlite/where.c
@@ -0,0 +1,1210 @@
+/*
+** 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.
+**
+** $Id$
+*/
+#include "sqliteInt.h"
+
+/*
+** 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 an AND operator.
+*/
+typedef struct ExprInfo ExprInfo;
+struct ExprInfo {
+  Expr *p;                /* Pointer to the subexpression */
+  u8 indexable;           /* True if this subexprssion is usable by an index */
+  short int idxLeft;      /* p->pLeft is a column in this table number. -1 if
+                          ** p->pLeft is not the column of any table */
+  short int idxRight;     /* p->pRight is a column in this table number. -1 if
+                          ** p->pRight is not the column of any table */
+  unsigned prereqLeft;    /* Bitmask of tables referenced by p->pLeft */
+  unsigned prereqRight;   /* Bitmask of tables referenced by p->pRight */
+  unsigned prereqAll;     /* Bitmask of tables referenced by p */
+};
+
+/*
+** An instance of the following structure keeps track of a mapping
+** between VDBE cursor numbers and bitmasks.  The VDBE cursor numbers
+** are small integers contained in SrcList_item.iCursor and Expr.iTable
+** fields.  For any given WHERE clause, we want to track which cursors
+** are being used, so we assign a single bit in a 32-bit word to track
+** that cursor.  Then a 32-bit integer is able to show the set of all
+** cursors being used.
+*/
+typedef struct ExprMaskSet ExprMaskSet;
+struct ExprMaskSet {
+  int n;          /* Number of assigned cursor values */
+  int ix[31];     /* Cursor assigned to each bit */
+};
+
+/*
+** Determine the number of elements in an array.
+*/
+#define ARRAYSIZE(X)  (sizeof(X)/sizeof(X[0]))
+
+/*
+** This routine is used to divide the WHERE expression into subexpressions
+** separated by the AND operator.
+**
+** aSlot[] is an array of subexpressions structures.
+** There are nSlot spaces left in this array.  This routine attempts to
+** split pExpr into subexpressions and fills aSlot[] with those subexpressions.
+** The return value is the number of slots filled.
+*/
+static int exprSplit(int nSlot, ExprInfo *aSlot, Expr *pExpr){
+  int cnt = 0;
+  if( pExpr==0 || nSlot<1 ) return 0;
+  if( nSlot==1 || pExpr->op!=TK_AND ){
+    aSlot[0].p = pExpr;
+    return 1;
+  }
+  if( pExpr->pLeft->op!=TK_AND ){
+    aSlot[0].p = pExpr->pLeft;
+    cnt = 1 + exprSplit(nSlot-1, &aSlot[1], pExpr->pRight);
+  }else{
+    cnt = exprSplit(nSlot, aSlot, pExpr->pLeft);
+    cnt += exprSplit(nSlot-cnt, &aSlot[cnt], pExpr->pRight);
+  }
+  return cnt;
+}
+
+/*
+** Initialize an expression mask set
+*/
+#define initMaskSet(P)  memset(P, 0, sizeof(*P))
+
+/*
+** Return the bitmask for the given cursor.  Assign a new bitmask
+** if this is the first time the cursor has been seen.
+*/
+static int getMask(ExprMaskSet *pMaskSet, int iCursor){
+  int i;
+  for(i=0; i<pMaskSet->n; i++){
+    if( pMaskSet->ix[i]==iCursor ) return 1<<i;
+  }
+  if( i==pMaskSet->n && i<ARRAYSIZE(pMaskSet->ix) ){
+    pMaskSet->n++;
+    pMaskSet->ix[i] = iCursor;
+    return 1<<i;
+  }
+  return 0;
+}
+
+/*
+** Destroy an expression mask set
+*/
+#define freeMaskSet(P)   /* NO-OP */
+
+/*
+** This routine walks (recursively) an expression tree and generates
+** a bitmask indicating which tables are used in that expression
+** tree.
+**
+** In order for this routine to work, the calling function must have
+** previously invoked sqlite3ExprResolveIds() on the expression.  See
+** the header comment on that routine for additional information.
+** The sqlite3ExprResolveIds() routines looks for column names and
+** sets their opcodes to TK_COLUMN and their Expr.iTable fields to
+** the VDBE cursor number of the table.
+*/
+static int exprTableUsage(ExprMaskSet *pMaskSet, Expr *p){
+  unsigned int mask = 0;
+  if( p==0 ) return 0;
+  if( p->op==TK_COLUMN ){
+    mask = getMask(pMaskSet, p->iTable);
+    if( mask==0 ) mask = -1;
+    return mask;
+  }
+  if( p->pRight ){
+    mask = exprTableUsage(pMaskSet, p->pRight);
+  }
+  if( p->pLeft ){
+    mask |= exprTableUsage(pMaskSet, p->pLeft);
+  }
+  if( p->pList ){
+    int i;
+    for(i=0; i<p->pList->nExpr; i++){
+      mask |= exprTableUsage(pMaskSet, p->pList->a[i].pExpr);
+    }
+  }
+  return mask;
+}
+
+/*
+** Return TRUE if the given operator is one of the operators that is
+** allowed for an indexable WHERE clause.  The allowed operators are
+** "=", "<", ">", "<=", ">=", and "IN".
+*/
+static int allowedOp(int op){
+  assert( TK_GT==TK_LE-1 && TK_LE==TK_LT-1 && TK_LT==TK_GE-1 && TK_EQ==TK_GT-1);
+  return op==TK_IN || (op>=TK_EQ && op<=TK_GE);
+}
+
+/*
+** Swap two integers.
+*/
+#define SWAP(TYPE,A,B) {TYPE t=A; A=B; B=t;}
+
+/*
+** Return the index in the SrcList that uses cursor iCur.  If iCur is
+** used by the first entry in SrcList return 0.  If iCur is used by
+** the second entry return 1.  And so forth.
+**
+** SrcList is the set of tables in the FROM clause in the order that
+** they will be processed.  The value returned here gives us an index
+** of which tables will be processed first.
+*/
+static int tableOrder(SrcList *pList, int iCur){
+  int i;
+  for(i=0; i<pList->nSrc; i++){
+    if( pList->a[i].iCursor==iCur ) return i;
+  }
+  return -1;
+}
+
+/*
+** The input to this routine is an ExprInfo structure with only the
+** "p" field filled in.  The job of this routine is to analyze the
+** subexpression and populate all the other fields of the ExprInfo
+** structure.
+*/
+static void exprAnalyze(SrcList *pSrc, ExprMaskSet *pMaskSet, ExprInfo *pInfo){
+  Expr *pExpr = pInfo->p;
+  pInfo->prereqLeft = exprTableUsage(pMaskSet, pExpr->pLeft);
+  pInfo->prereqRight = exprTableUsage(pMaskSet, pExpr->pRight);
+  pInfo->prereqAll = exprTableUsage(pMaskSet, pExpr);
+  pInfo->indexable = 0;
+  pInfo->idxLeft = -1;
+  pInfo->idxRight = -1;
+  if( allowedOp(pExpr->op) && (pInfo->prereqRight & pInfo->prereqLeft)==0 ){
+    if( pExpr->pRight && pExpr->pRight->op==TK_COLUMN ){
+      pInfo->idxRight = pExpr->pRight->iTable;
+      pInfo->indexable = 1;
+    }
+    if( pExpr->pLeft->op==TK_COLUMN ){
+      pInfo->idxLeft = pExpr->pLeft->iTable;
+      pInfo->indexable = 1;
+    }
+  }
+  if( pInfo->indexable ){
+    assert( pInfo->idxLeft!=pInfo->idxRight );
+
+    /* We want the expression to be of the form "X = expr", not "expr = X".
+    ** So flip it over if necessary.  If the expression is "X = Y", then
+    ** we want Y to come from an earlier table than X.
+    **
+    ** The collating sequence rule is to always choose the left expression.
+    ** So if we do a flip, we also have to move the collating sequence.
+    */
+    if( tableOrder(pSrc,pInfo->idxLeft)<tableOrder(pSrc,pInfo->idxRight) ){
+      assert( pExpr->op!=TK_IN );
+      SWAP(CollSeq*,pExpr->pRight->pColl,pExpr->pLeft->pColl);
+      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;
+      }
+      SWAP(unsigned, pInfo->prereqLeft, pInfo->prereqRight);
+      SWAP(short int, pInfo->idxLeft, pInfo->idxRight);
+    }
+  }      
+
+}
+
+/*
+** pOrderBy is an ORDER BY clause from a SELECT statement.  pTab is the
+** left-most table in the FROM clause of that same SELECT statement and
+** the table has a cursor number of "base".
+**
+** This routine attempts to find an index for pTab that generates the
+** correct record sequence for the given ORDER BY clause.  The return value
+** is a pointer to an index that does the job.  NULL is returned if the
+** table has no index that will generate the correct sort order.
+**
+** If there are two or more indices that generate the correct sort order
+** and pPreferredIdx is one of those indices, then return pPreferredIdx.
+**
+** nEqCol is the number of columns of pPreferredIdx that are used as
+** equality constraints.  Any index returned must have exactly this same
+** set of columns.  The ORDER BY clause only matches index columns beyond the
+** the first nEqCol columns.
+**
+** All terms of the ORDER BY clause must be either ASC or DESC.  The
+** *pbRev value is set to 1 if the ORDER BY clause is all DESC and it is
+** set to 0 if the ORDER BY clause is all ASC.
+*/
+static Index *findSortingIndex(
+  Parse *pParse,
+  Table *pTab,            /* The table to be sorted */
+  int base,               /* Cursor number for pTab */
+  ExprList *pOrderBy,     /* The ORDER BY clause */
+  Index *pPreferredIdx,   /* Use this index, if possible and not NULL */
+  int nEqCol,             /* Number of index columns used with == constraints */
+  int *pbRev              /* Set to 1 if ORDER BY is DESC */
+){
+  int i, j;
+  Index *pMatch;
+  Index *pIdx;
+  int sortOrder;
+  sqlite3 *db = pParse->db;
+
+  assert( pOrderBy!=0 );
+  assert( pOrderBy->nExpr>0 );
+  sortOrder = pOrderBy->a[0].sortOrder;
+  for(i=0; i<pOrderBy->nExpr; i++){
+    Expr *p;
+    if( pOrderBy->a[i].sortOrder!=sortOrder ){
+      /* Indices can only be used if all ORDER BY terms are either
+      ** DESC or ASC.  Indices cannot be used on a mixture. */
+      return 0;
+    }
+    p = pOrderBy->a[i].pExpr;
+    if( p->op!=TK_COLUMN || p->iTable!=base ){
+      /* Can not use an index sort on anything that is not a column in the
+      ** left-most table of the FROM clause */
+      return 0;
+    }
+  }
+
+  /* If we get this far, it means the ORDER BY clause consists only of
+  ** ascending columns in the left-most table of the FROM clause.  Now
+  ** check for a matching index.
+  */
+  pMatch = 0;
+  for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+    int nExpr = pOrderBy->nExpr;
+    if( pIdx->nColumn < nEqCol || pIdx->nColumn < nExpr ) continue;
+    for(i=j=0; i<nEqCol; i++){
+      CollSeq *pColl = sqlite3ExprCollSeq(pParse, pOrderBy->a[j].pExpr);
+      if( !pColl ) pColl = db->pDfltColl;
+      if( pPreferredIdx->aiColumn[i]!=pIdx->aiColumn[i] ) break;
+      if( pPreferredIdx->keyInfo.aColl[i]!=pIdx->keyInfo.aColl[i] ) break;
+      if( j<nExpr && 
+          pOrderBy->a[j].pExpr->iColumn==pIdx->aiColumn[i] &&
+          pColl==pIdx->keyInfo.aColl[i]
+      ){ 
+        j++; 
+      }
+    }
+    if( i<nEqCol ) continue;
+    for(i=0; i+j<nExpr; i++){
+      CollSeq *pColl = sqlite3ExprCollSeq(pParse, pOrderBy->a[i+j].pExpr);
+      if( !pColl ) pColl = db->pDfltColl;
+      if( pOrderBy->a[i+j].pExpr->iColumn!=pIdx->aiColumn[i+nEqCol] ||
+          pColl!=pIdx->keyInfo.aColl[i+nEqCol] ) break;
+    }
+    if( i+j>=nExpr ){
+      pMatch = pIdx;
+      if( pIdx==pPreferredIdx ) break;
+    }
+  }
+  if( pMatch && pbRev ){
+    *pbRev = sortOrder==SQLITE_SO_DESC;
+  }
+  return pMatch;
+}
+
+/*
+** 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 did not originate
+** 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.  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, Expr **ppExpr){
+  Expr *pExpr = *ppExpr;
+  if( pLevel->iLeftJoin==0 || ExprHasProperty(pExpr, EP_FromJoin) ){
+    *ppExpr = 0;
+  }
+}
+
+/*
+** Generate code that builds a probe for an index.  Details:
+**
+**    *  Check the top nColumn entries on the stack.  If any
+**       of those entries are NULL, jump immediately to brk,
+**       which is the loop exit, since no index entry will match
+**       if any part of the key is NULL.
+**
+**    *  Construct a probe entry from the top nColumn entries in
+**       the stack with affinities appropriate for index pIdx.
+*/
+static void buildIndexProbe(Vdbe *v, int nColumn, int brk, Index *pIdx){
+  sqlite3VdbeAddOp(v, OP_NotNull, -nColumn, sqlite3VdbeCurrentAddr(v)+3);
+  sqlite3VdbeAddOp(v, OP_Pop, nColumn, 0);
+  sqlite3VdbeAddOp(v, OP_Goto, 0, brk);
+  sqlite3VdbeAddOp(v, OP_MakeRecord, nColumn, 0);
+  sqlite3IndexAffinityStr(v, pIdx);
+}
+
+/*
+** Generate code for an equality term of the WHERE clause.  An equality
+** term can be either X=expr  or X IN (...).   pTerm is the X.  
+*/
+static void codeEqualityTerm(
+  Parse *pParse,      /* The parsing context */
+  ExprInfo *pTerm,    /* The term of the WHERE clause to be coded */
+  int brk,            /* Jump here to abandon the loop */
+  WhereLevel *pLevel  /* When level of the FROM clause we are working on */
+){
+  Expr *pX = pTerm->p;
+  if( pX->op!=TK_IN ){
+    assert( pX->op==TK_EQ );
+    sqlite3ExprCode(pParse, pX->pRight);
+  }else{
+    int iTab = pX->iTable;
+    Vdbe *v = pParse->pVdbe;
+    sqlite3VdbeAddOp(v, OP_Rewind, iTab, brk);
+    sqlite3VdbeAddOp(v, OP_KeyAsData, iTab, 1);
+    pLevel->inP2 = sqlite3VdbeAddOp(v, OP_IdxColumn, iTab, 0);
+    pLevel->inOp = OP_Next;
+    pLevel->inP1 = iTab;
+  }
+  disableTerm(pLevel, &pTerm->p);
+}
+
+
+/*
+** 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                         /
+**
+** 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.
+**
+** 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
+**
+** *ppOrderBy is a pointer to the ORDER BY clause 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 ppOrderBy is NULL.
+**
+** If an index can be used so that the natural output order of the table
+** scan is correct for the ORDER BY clause, then that index is used and
+** *ppOrderBy is set to NULL.  This is an optimization that prevents an
+** unnecessary sort of the result set if an index appropriate for the
+** ORDER BY clause already exists.
+**
+** If the where clause loops cannot be arranged to provide the correct
+** output order, then the *ppOrderBy is unchanged.
+*/
+WhereInfo *sqlite3WhereBegin(
+  Parse *pParse,       /* The parser context */
+  SrcList *pTabList,   /* A list of all tables to be scanned */
+  Expr *pWhere,        /* The WHERE clause */
+  int pushKey,         /* If TRUE, leave the table key on the stack */
+  ExprList **ppOrderBy /* An ORDER BY clause, or NULL */
+){
+  int i;                     /* Loop counter */
+  WhereInfo *pWInfo;         /* Will become the return value of this function */
+  Vdbe *v = pParse->pVdbe;   /* The virtual database engine */
+  int brk, cont = 0;         /* Addresses used during code generation */
+  int nExpr;           /* Number of subexpressions in the WHERE clause */
+  int loopMask;        /* One bit set for each outer loop */
+  int haveKey = 0;     /* True if KEY is on the stack */
+  ExprInfo *pTerm;     /* A single term in the WHERE clause; ptr to aExpr[] */
+  ExprMaskSet maskSet; /* The expression mask set */
+  int iDirectEq[32];   /* Term of the form ROWID==X for the N-th table */
+  int iDirectLt[32];   /* Term of the form ROWID<X or ROWID<=X */
+  int iDirectGt[32];   /* Term of the form ROWID>X or ROWID>=X */
+  ExprInfo aExpr[101]; /* The WHERE clause is divided into these terms */
+
+  /* pushKey is only allowed if there is a single table (as in an INSERT or
+  ** UPDATE statement)
+  */
+  assert( pushKey==0 || pTabList->nSrc==1 );
+
+  /* Split the WHERE clause into separate subexpressions where each
+  ** subexpression is separated by an AND operator.  If the aExpr[]
+  ** array fills up, the last entry might point to an expression which
+  ** contains additional unfactored AND operators.
+  */
+  initMaskSet(&maskSet);
+  memset(aExpr, 0, sizeof(aExpr));
+  nExpr = exprSplit(ARRAYSIZE(aExpr), aExpr, pWhere);
+  if( nExpr==ARRAYSIZE(aExpr) ){
+    sqlite3ErrorMsg(pParse, "WHERE clause too complex - no more "
+       "than %d terms allowed", (int)ARRAYSIZE(aExpr)-1);
+    return 0;
+  }
+  
+  /* Allocate and initialize the WhereInfo structure that will become the
+  ** return value.
+  */
+  pWInfo = sqliteMalloc( sizeof(WhereInfo) + pTabList->nSrc*sizeof(WhereLevel));
+  if( sqlite3_malloc_failed ){
+    /* sqliteFree(pWInfo); // Leak memory when malloc fails */
+    return 0;
+  }
+  pWInfo->pParse = pParse;
+  pWInfo->pTabList = pTabList;
+  pWInfo->iBreak = sqlite3VdbeMakeLabel(v);
+
+  /* Special case: a WHERE clause that is constant.  Evaluate the
+  ** expression and either jump over all of the code or fall thru.
+  */
+  if( pWhere && (pTabList->nSrc==0 || sqlite3ExprIsConstant(pWhere)) ){
+    sqlite3ExprIfFalse(pParse, pWhere, pWInfo->iBreak, 1);
+    pWhere = 0;
+  }
+
+  /* Analyze all of the subexpressions.
+  */
+  for(pTerm=aExpr, i=0; i<nExpr; i++, pTerm++){
+    TriggerStack *pStack;
+    exprAnalyze(pTabList, &maskSet, pTerm);
+
+    /* If we are executing a trigger body, remove all references to
+    ** new.* and old.* tables from the prerequisite masks.
+    */
+    if( (pStack = pParse->trigStack)!=0 ){
+      int x;
+      if( (x=pStack->newIdx) >= 0 ){
+        int mask = ~getMask(&maskSet, x);
+        pTerm->prereqRight &= mask;
+        pTerm->prereqLeft &= mask;
+        pTerm->prereqAll &= mask;
+      }
+      if( (x=pStack->oldIdx) >= 0 ){
+        int mask = ~getMask(&maskSet, x);
+        pTerm->prereqRight &= mask;
+        pTerm->prereqLeft &= mask;
+        pTerm->prereqAll &= mask;
+      }
+    }
+  }
+
+  /* Figure out what index to use (if any) for each nested loop.
+  ** Make pWInfo->a[i].pIdx point to the index to use for the i-th nested
+  ** loop where i==0 is the outer loop and i==pTabList->nSrc-1 is the inner
+  ** loop. 
+  **
+  ** If terms exist that use the ROWID of any table, then set the
+  ** iDirectEq[], iDirectLt[], or iDirectGt[] elements for that table
+  ** to the index of the term containing the ROWID.  We always prefer
+  ** to use a ROWID which can directly access a table rather than an
+  ** index which requires reading an index first to get the rowid then
+  ** doing a second read of the actual database table.
+  **
+  ** Actually, if there are more than 32 tables in the join, only the
+  ** first 32 tables are candidates for indices.  This is (again) due
+  ** to the limit of 32 bits in an integer bitmask.
+  */
+  loopMask = 0;
+  for(i=0; i<pTabList->nSrc && i<ARRAYSIZE(iDirectEq); i++){
+    int j;
+    WhereLevel *pLevel = &pWInfo->a[i];
+    int iCur = pTabList->a[i].iCursor;    /* The cursor for this table */
+    int mask = getMask(&maskSet, iCur);   /* Cursor mask for this table */
+    Table *pTab = pTabList->a[i].pTab;
+    Index *pIdx;
+    Index *pBestIdx = 0;
+    int bestScore = 0;
+
+    /* Check to see if there is an expression that uses only the
+    ** ROWID field of this table.  For terms of the form ROWID==expr
+    ** set iDirectEq[i] to the index of the term.  For terms of the
+    ** form ROWID<expr or ROWID<=expr set iDirectLt[i] to the term index.
+    ** For terms like ROWID>expr or ROWID>=expr set iDirectGt[i].
+    **
+    ** (Added:) Treat ROWID IN expr like ROWID=expr.
+    */
+    pLevel->iCur = -1;
+    iDirectEq[i] = -1;
+    iDirectLt[i] = -1;
+    iDirectGt[i] = -1;
+    for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
+      Expr *pX = pTerm->p;
+      if( pTerm->idxLeft==iCur && pX->pLeft->iColumn<0
+            && (pTerm->prereqRight & loopMask)==pTerm->prereqRight ){
+        switch( pX->op ){
+          case TK_IN:
+          case TK_EQ: iDirectEq[i] = j; break;
+          case TK_LE:
+          case TK_LT: iDirectLt[i] = j; break;
+          case TK_GE:
+          case TK_GT: iDirectGt[i] = j;  break;
+        }
+      }
+    }
+    if( iDirectEq[i]>=0 ){
+      loopMask |= mask;
+      pLevel->pIdx = 0;
+      continue;
+    }
+
+    /* Do a search for usable indices.  Leave pBestIdx pointing to
+    ** the "best" index.  pBestIdx is left set to NULL if no indices
+    ** are usable.
+    **
+    ** The best index is determined as follows.  For each of the
+    ** left-most terms that is fixed by an equality operator, add
+    ** 8 to the score.  The right-most term of the index may be
+    ** constrained by an inequality.  Add 1 if for an "x<..." constraint
+    ** and add 2 for an "x>..." constraint.  Chose the index that
+    ** gives the best score.
+    **
+    ** This scoring system is designed so that the score can later be
+    ** used to determine how the index is used.  If the score&7 is 0
+    ** then all constraints are equalities.  If score&1 is not 0 then
+    ** there is an inequality used as a termination key.  (ex: "x<...")
+    ** If score&2 is not 0 then there is an inequality used as the
+    ** start key.  (ex: "x>...").  A score or 4 is the special case
+    ** of an IN operator constraint.  (ex:  "x IN ...").
+    **
+    ** The IN operator (as in "<expr> IN (...)") is treated the same as
+    ** an equality comparison except that it can only be used on the
+    ** left-most column of an index and other terms of the WHERE clause
+    ** cannot be used in conjunction with the IN operator to help satisfy
+    ** other columns of the index.
+    */
+    for(pIdx=pTab->pIndex; pIdx; pIdx=pIdx->pNext){
+      int eqMask = 0;  /* Index columns covered by an x=... term */
+      int ltMask = 0;  /* Index columns covered by an x<... term */
+      int gtMask = 0;  /* Index columns covered by an x>... term */
+      int inMask = 0;  /* Index columns covered by an x IN .. term */
+      int nEq, m, score;
+
+      if( pIdx->nColumn>32 ) continue;  /* Ignore indices too many columns */
+      for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
+        Expr *pX = pTerm->p;
+        CollSeq *pColl = sqlite3ExprCollSeq(pParse, pX->pLeft);
+        if( !pColl && pX->pRight ){
+          pColl = sqlite3ExprCollSeq(pParse, pX->pRight);
+        }
+        if( !pColl ){
+          pColl = pParse->db->pDfltColl;
+        }
+        if( pTerm->idxLeft==iCur 
+             && (pTerm->prereqRight & loopMask)==pTerm->prereqRight ){
+          int iColumn = pX->pLeft->iColumn;
+          int k;
+          char idxaff = pIdx->pTable->aCol[iColumn].affinity; 
+          for(k=0; k<pIdx->nColumn; k++){
+            /* If the collating sequences or affinities don't match, 
+            ** ignore this index.  */
+            if( pColl!=pIdx->keyInfo.aColl[k] ) continue;
+            if( !sqlite3IndexAffinityOk(pX, idxaff) ) continue;
+            if( pIdx->aiColumn[k]==iColumn ){
+              switch( pX->op ){
+                case TK_IN: {
+                  if( k==0 ) inMask |= 1;
+                  break;
+                }
+                case TK_EQ: {
+                  eqMask |= 1<<k;
+                  break;
+                }
+                case TK_LE:
+                case TK_LT: {
+                  ltMask |= 1<<k;
+                  break;
+                }
+                case TK_GE:
+                case TK_GT: {
+                  gtMask |= 1<<k;
+                  break;
+                }
+                default: {
+                  /* CANT_HAPPEN */
+                  assert( 0 );
+                  break;
+                }
+              }
+              break;
+            }
+          }
+        }
+      }
+
+      /* The following loop ends with nEq set to the number of columns
+      ** on the left of the index with == constraints.
+      */
+      for(nEq=0; nEq<pIdx->nColumn; nEq++){
+        m = (1<<(nEq+1))-1;
+        if( (m & eqMask)!=m ) break;
+      }
+      score = nEq*8;   /* Base score is 8 times number of == constraints */
+      m = 1<<nEq;
+      if( m & ltMask ) score++;    /* Increase score for a < constraint */
+      if( m & gtMask ) score+=2;   /* Increase score for a > constraint */
+      if( score==0 && inMask ) score = 4;  /* Default score for IN constraint */
+      if( score>bestScore ){
+        pBestIdx = pIdx;
+        bestScore = score;
+      }
+    }
+    pLevel->pIdx = pBestIdx;
+    pLevel->score = bestScore;
+    pLevel->bRev = 0;
+    loopMask |= mask;
+    if( pBestIdx ){
+      pLevel->iCur = pParse->nTab++;
+    }
+  }
+
+  /* Check to see if the ORDER BY clause is or can be satisfied by the
+  ** use of an index on the first table.
+  */
+  if( ppOrderBy && *ppOrderBy && pTabList->nSrc>0 ){
+     Index *pSortIdx;
+     Index *pIdx;
+     Table *pTab;
+     int bRev = 0;
+
+     pTab = pTabList->a[0].pTab;
+     pIdx = pWInfo->a[0].pIdx;
+     if( pIdx && pWInfo->a[0].score==4 ){
+       /* If there is already an IN index on the left-most table,
+       ** it will not give the correct sort order.
+       ** So, pretend that no suitable index is found.
+       */
+       pSortIdx = 0;
+     }else if( iDirectEq[0]>=0 || iDirectLt[0]>=0 || iDirectGt[0]>=0 ){
+       /* If the left-most column is accessed using its ROWID, then do
+       ** not try to sort by index.
+       */
+       pSortIdx = 0;
+     }else{
+       int nEqCol = (pWInfo->a[0].score+4)/8;
+       pSortIdx = findSortingIndex(pParse, pTab, pTabList->a[0].iCursor, 
+                                   *ppOrderBy, pIdx, nEqCol, &bRev);
+     }
+     if( pSortIdx && (pIdx==0 || pIdx==pSortIdx) ){
+       if( pIdx==0 ){
+         pWInfo->a[0].pIdx = pSortIdx;
+         pWInfo->a[0].iCur = pParse->nTab++;
+       }
+       pWInfo->a[0].bRev = bRev;
+       *ppOrderBy = 0;
+     }
+  }
+
+  /* Open all tables in the pTabList and all indices used by those tables.
+  */
+  sqlite3CodeVerifySchema(pParse, -1); /* Insert the cookie verifier Goto */
+  for(i=0; i<pTabList->nSrc; i++){
+    Table *pTab;
+    Index *pIx;
+
+    pTab = pTabList->a[i].pTab;
+    if( pTab->isTransient || pTab->pSelect ) continue;
+    sqlite3OpenTableForReading(v, pTabList->a[i].iCursor, pTab);
+    sqlite3CodeVerifySchema(pParse, pTab->iDb);
+    if( (pIx = pWInfo->a[i].pIdx)!=0 ){
+      sqlite3VdbeAddOp(v, OP_Integer, pIx->iDb, 0);
+      sqlite3VdbeOp3(v, OP_OpenRead, pWInfo->a[i].iCur, pIx->tnum,
+                     (char*)&pIx->keyInfo, P3_KEYINFO);
+    }
+  }
+
+  /* Generate the code to do the search
+  */
+  loopMask = 0;
+  for(i=0; i<pTabList->nSrc; i++){
+    int j, k;
+    int iCur = pTabList->a[i].iCursor;
+    Index *pIdx;
+    WhereLevel *pLevel = &pWInfo->a[i];
+
+    /* 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( i>0 && (pTabList->a[i-1].jointype & JT_LEFT)!=0 ){
+      if( !pParse->nMem ) pParse->nMem++;
+      pLevel->iLeftJoin = pParse->nMem++;
+      sqlite3VdbeAddOp(v, OP_String8, 0, 0);
+      sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
+      VdbeComment((v, "# init LEFT JOIN no-match flag"));
+    }
+
+    pIdx = pLevel->pIdx;
+    pLevel->inOp = OP_Noop;
+    if( i<ARRAYSIZE(iDirectEq) && (k = iDirectEq[i])>=0 ){
+      /* Case 1:  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( k<nExpr );
+      pTerm = &aExpr[k];
+      assert( pTerm->p!=0 );
+      assert( pTerm->idxLeft==iCur );
+      brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
+      codeEqualityTerm(pParse, pTerm, brk, pLevel);
+      cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
+      sqlite3VdbeAddOp(v, OP_MustBeInt, 1, brk);
+      haveKey = 0;
+      sqlite3VdbeAddOp(v, OP_NotExists, iCur, brk);
+      pLevel->op = OP_Noop;
+    }else if( pIdx!=0 && pLevel->score>0 && pLevel->score%4==0 ){
+      /* Case 2:  There is an index and all terms of the WHERE clause that
+      **          refer to the index use the "==" or "IN" operators.
+      */
+      int start;
+      int nColumn = (pLevel->score+4)/8;
+      brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
+
+      /* For each column of the index, find the term of the WHERE clause that
+      ** constraints that column.  If the WHERE clause term is X=expr, then
+      ** evaluation expr and leave the result on the stack */
+      for(j=0; j<nColumn; j++){
+        for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){
+          Expr *pX = pTerm->p;
+          if( pX==0 ) continue;
+          if( pTerm->idxLeft==iCur
+             && (pTerm->prereqRight & loopMask)==pTerm->prereqRight 
+             && pX->pLeft->iColumn==pIdx->aiColumn[j]
+          ){
+            char idxaff = pIdx->pTable->aCol[pX->pLeft->iColumn].affinity;
+            if( sqlite3IndexAffinityOk(pX, idxaff) ){
+              codeEqualityTerm(pParse, pTerm, brk, pLevel);
+              break;
+            }
+          }
+        }
+      }
+      pLevel->iMem = pParse->nMem++;
+      cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
+      buildIndexProbe(v, nColumn, brk, pIdx);
+      sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 0);
+
+      /* Generate code (1) to move to the first matching element of the table.
+      ** Then generate code (2) that jumps to "brk" after the cursor is past
+      ** the last matching element of the table.  The code (1) is executed
+      ** once to initialize the search, the code (2) is executed before each
+      ** iteration of the scan to see if the scan has finished. */
+      if( pLevel->bRev ){
+        /* Scan in reverse order */
+        sqlite3VdbeAddOp(v, OP_MoveLe, pLevel->iCur, brk);
+        start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
+        sqlite3VdbeAddOp(v, OP_IdxLT, pLevel->iCur, brk);
+        pLevel->op = OP_Prev;
+      }else{
+        /* Scan in the forward order */
+        sqlite3VdbeAddOp(v, OP_MoveGe, pLevel->iCur, brk);
+        start = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
+        sqlite3VdbeOp3(v, OP_IdxGE, pLevel->iCur, brk, "+", P3_STATIC);
+        pLevel->op = OP_Next;
+      }
+      sqlite3VdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
+      sqlite3VdbeAddOp(v, OP_IdxIsNull, nColumn, cont);
+      sqlite3VdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
+      if( i==pTabList->nSrc-1 && pushKey ){
+        haveKey = 1;
+      }else{
+        sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
+        haveKey = 0;
+      }
+      pLevel->p1 = pLevel->iCur;
+      pLevel->p2 = start;
+    }else if( i<ARRAYSIZE(iDirectLt) && (iDirectLt[i]>=0 || iDirectGt[i]>=0) ){
+      /* Case 3:  We have an inequality comparison against the ROWID field.
+      */
+      int testOp = OP_Noop;
+      int start;
+
+      brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
+      cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
+      if( iDirectGt[i]>=0 ){
+        Expr *pX;
+        k = iDirectGt[i];
+        assert( k<nExpr );
+        pTerm = &aExpr[k];
+        pX = pTerm->p;
+        assert( pX!=0 );
+        assert( pTerm->idxLeft==iCur );
+        sqlite3ExprCode(pParse, pX->pRight);
+        sqlite3VdbeAddOp(v, OP_ForceInt, pX->op==TK_LT || pX->op==TK_GT, brk);
+        sqlite3VdbeAddOp(v, OP_MoveGe, iCur, brk);
+        disableTerm(pLevel, &pTerm->p);
+      }else{
+        sqlite3VdbeAddOp(v, OP_Rewind, iCur, brk);
+      }
+      if( iDirectLt[i]>=0 ){
+        Expr *pX;
+        k = iDirectLt[i];
+        assert( k<nExpr );
+        pTerm = &aExpr[k];
+        pX = pTerm->p;
+        assert( pX!=0 );
+        assert( pTerm->idxLeft==iCur );
+        sqlite3ExprCode(pParse, pX->pRight);
+        pLevel->iMem = pParse->nMem++;
+        sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
+        if( pX->op==TK_LT || pX->op==TK_GT ){
+          testOp = OP_Ge;
+        }else{
+          testOp = OP_Gt;
+        }
+        disableTerm(pLevel, &pTerm->p);
+      }
+      start = sqlite3VdbeCurrentAddr(v);
+      pLevel->op = OP_Next;
+      pLevel->p1 = iCur;
+      pLevel->p2 = start;
+      if( testOp!=OP_Noop ){
+        sqlite3VdbeAddOp(v, OP_Recno, iCur, 0);
+        sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
+        sqlite3VdbeAddOp(v, testOp, 0, brk);
+      }
+      haveKey = 0;
+    }else if( pIdx==0 ){
+      /* Case 4:  There is no usable index.  We must do a complete
+      **          scan of the entire database table.
+      */
+      int start;
+
+      brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
+      cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
+      sqlite3VdbeAddOp(v, OP_Rewind, iCur, brk);
+      start = sqlite3VdbeCurrentAddr(v);
+      pLevel->op = OP_Next;
+      pLevel->p1 = iCur;
+      pLevel->p2 = start;
+      haveKey = 0;
+    }else{
+      /* Case 5: The WHERE clause term that refers to the right-most
+      **         column of the index is an inequality.  For example, if
+      **         the index is on (x,y,z) and the WHERE clause is of the
+      **         form "x=5 AND y<10" then this case is used.  Only the
+      **         right-most column can be an inequality - the rest must
+      **         use the "==" operator.
+      **
+      **         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.
+      */
+      int score = pLevel->score;
+      int nEqColumn = score/8;
+      int start;
+      int leFlag=0, geFlag=0;
+      int testOp;
+
+      /* Evaluate the equality constraints
+      */
+      for(j=0; j<nEqColumn; j++){
+        int iIdxCol = pIdx->aiColumn[j];
+        for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){
+          Expr *pX = pTerm->p;
+          if( pX==0 ) continue;
+          if( pTerm->idxLeft==iCur
+             && pX->op==TK_EQ
+             && (pTerm->prereqRight & loopMask)==pTerm->prereqRight 
+             && pX->pLeft->iColumn==iIdxCol
+          ){
+            sqlite3ExprCode(pParse, pX->pRight);
+            disableTerm(pLevel, &pTerm->p);
+            break;
+          }
+        }
+      }
+
+      /* Duplicate the equality term values because they will all be
+      ** used twice: once to make the termination key and once to make the
+      ** start key.
+      */
+      for(j=0; j<nEqColumn; j++){
+        sqlite3VdbeAddOp(v, OP_Dup, nEqColumn-1, 0);
+      }
+
+      /* Labels for the beginning and end of the loop
+      */
+      cont = pLevel->cont = sqlite3VdbeMakeLabel(v);
+      brk = pLevel->brk = sqlite3VdbeMakeLabel(v);
+
+      /* Generate the termination key.  This is the key value that
+      ** will end the search.  There is no termination key if there
+      ** are no equality terms and no "X<..." term.
+      **
+      ** 2002-Dec-04: On a reverse-order scan, the so-called "termination"
+      ** key computed here really ends up being the start key.
+      */
+      if( (score & 1)!=0 ){
+        for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){
+          Expr *pX = pTerm->p;
+          if( pX==0 ) continue;
+          if( pTerm->idxLeft==iCur
+             && (pX->op==TK_LT || pX->op==TK_LE)
+             && (pTerm->prereqRight & loopMask)==pTerm->prereqRight 
+             && pX->pLeft->iColumn==pIdx->aiColumn[j]
+          ){
+            sqlite3ExprCode(pParse, pX->pRight);
+            leFlag = pX->op==TK_LE;
+            disableTerm(pLevel, &pTerm->p);
+            break;
+          }
+        }
+        testOp = OP_IdxGE;
+      }else{
+        testOp = nEqColumn>0 ? OP_IdxGE : OP_Noop;
+        leFlag = 1;
+      }
+      if( testOp!=OP_Noop ){
+        int nCol = nEqColumn + (score & 1);
+        pLevel->iMem = pParse->nMem++;
+        buildIndexProbe(v, nCol, brk, pIdx);
+        if( pLevel->bRev ){
+          int op = leFlag ? OP_MoveLe : OP_MoveLt;
+          sqlite3VdbeAddOp(v, op, pLevel->iCur, brk);
+        }else{
+          sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
+        }
+      }else if( pLevel->bRev ){
+        sqlite3VdbeAddOp(v, OP_Last, pLevel->iCur, brk);
+      }
+
+      /* Generate the start key.  This is the key that defines the lower
+      ** bound on the search.  There is no start key if there are no
+      ** equality terms and if there is no "X>..." term.  In
+      ** that case, generate a "Rewind" instruction in place of the
+      ** start key search.
+      **
+      ** 2002-Dec-04: In the case of a reverse-order search, the so-called
+      ** "start" key really ends up being used as the termination key.
+      */
+      if( (score & 2)!=0 ){
+        for(pTerm=aExpr, k=0; k<nExpr; k++, pTerm++){
+          Expr *pX = pTerm->p;
+          if( pX==0 ) continue;
+          if( pTerm->idxLeft==iCur
+             && (pX->op==TK_GT || pX->op==TK_GE)
+             && (pTerm->prereqRight & loopMask)==pTerm->prereqRight 
+             && pX->pLeft->iColumn==pIdx->aiColumn[j]
+          ){
+            sqlite3ExprCode(pParse, pX->pRight);
+            geFlag = pX->op==TK_GE;
+            disableTerm(pLevel, &pTerm->p);
+            break;
+          }
+        }
+      }else{
+        geFlag = 1;
+      }
+      if( nEqColumn>0 || (score&2)!=0 ){
+        int nCol = nEqColumn + ((score&2)!=0);
+        buildIndexProbe(v, nCol, brk, pIdx);
+        if( pLevel->bRev ){
+          pLevel->iMem = pParse->nMem++;
+          sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iMem, 1);
+          testOp = OP_IdxLT;
+        }else{
+          int op = geFlag ? OP_MoveGe : OP_MoveGt;
+          sqlite3VdbeAddOp(v, op, pLevel->iCur, brk);
+        }
+      }else if( pLevel->bRev ){
+        testOp = OP_Noop;
+      }else{
+        sqlite3VdbeAddOp(v, OP_Rewind, pLevel->iCur, brk);
+      }
+
+      /* Generate the the top of the loop.  If there is a termination
+      ** key we have to test for that key and abort at the top of the
+      ** loop.
+      */
+      start = sqlite3VdbeCurrentAddr(v);
+      if( testOp!=OP_Noop ){
+        sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iMem, 0);
+        sqlite3VdbeAddOp(v, testOp, pLevel->iCur, brk);
+        if( (leFlag && !pLevel->bRev) || (!geFlag && pLevel->bRev) ){
+          sqlite3VdbeChangeP3(v, -1, "+", P3_STATIC);
+        }
+      }
+      sqlite3VdbeAddOp(v, OP_RowKey, pLevel->iCur, 0);
+      sqlite3VdbeAddOp(v, OP_IdxIsNull, nEqColumn + (score & 1), cont);
+      sqlite3VdbeAddOp(v, OP_IdxRecno, pLevel->iCur, 0);
+      if( i==pTabList->nSrc-1 && pushKey ){
+        haveKey = 1;
+      }else{
+        sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
+        haveKey = 0;
+      }
+
+      /* Record the instruction used to terminate the loop.
+      */
+      pLevel->op = pLevel->bRev ? OP_Prev : OP_Next;
+      pLevel->p1 = pLevel->iCur;
+      pLevel->p2 = start;
+    }
+    loopMask |= getMask(&maskSet, iCur);
+
+    /* Insert code to test every subexpression that can be completely
+    ** computed using the current set of tables.
+    */
+    for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
+      if( pTerm->p==0 ) continue;
+      if( (pTerm->prereqAll & loopMask)!=pTerm->prereqAll ) continue;
+      if( pLevel->iLeftJoin && !ExprHasProperty(pTerm->p,EP_FromJoin) ){
+        continue;
+      }
+      if( haveKey ){
+        haveKey = 0;
+        sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
+      }
+      sqlite3ExprIfFalse(pParse, pTerm->p, cont, 1);
+      pTerm->p = 0;
+    }
+    brk = cont;
+
+    /* 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->top = sqlite3VdbeCurrentAddr(v);
+      sqlite3VdbeAddOp(v, OP_Integer, 1, 0);
+      sqlite3VdbeAddOp(v, OP_MemStore, pLevel->iLeftJoin, 1);
+      VdbeComment((v, "# record LEFT JOIN hit"));
+      for(pTerm=aExpr, j=0; j<nExpr; j++, pTerm++){
+        if( pTerm->p==0 ) continue;
+        if( (pTerm->prereqAll & loopMask)!=pTerm->prereqAll ) continue;
+        if( haveKey ){
+          /* Cannot happen.  "haveKey" can only be true if pushKey is true
+          ** an pushKey can only be true for DELETE and UPDATE and there are
+          ** no outer joins with DELETE and UPDATE.
+          */
+          haveKey = 0;
+          sqlite3VdbeAddOp(v, OP_MoveGe, iCur, 0);
+        }
+        sqlite3ExprIfFalse(pParse, pTerm->p, cont, 1);
+        pTerm->p = 0;
+      }
+    }
+  }
+  pWInfo->iContinue = cont;
+  if( pushKey && !haveKey ){
+    sqlite3VdbeAddOp(v, OP_Recno, pTabList->a[0].iCursor, 0);
+  }
+  freeMaskSet(&maskSet);
+  return pWInfo;
+}
+
+/*
+** Generate the end of the WHERE loop.  See comments on 
+** sqlite3WhereBegin() for additional information.
+*/
+void sqlite3WhereEnd(WhereInfo *pWInfo){
+  Vdbe *v = pWInfo->pParse->pVdbe;
+  int i;
+  WhereLevel *pLevel;
+  SrcList *pTabList = pWInfo->pTabList;
+
+  for(i=pTabList->nSrc-1; i>=0; i--){
+    pLevel = &pWInfo->a[i];
+    sqlite3VdbeResolveLabel(v, pLevel->cont);
+    if( pLevel->op!=OP_Noop ){
+      sqlite3VdbeAddOp(v, pLevel->op, pLevel->p1, pLevel->p2);
+    }
+    sqlite3VdbeResolveLabel(v, pLevel->brk);
+    if( pLevel->inOp!=OP_Noop ){
+      sqlite3VdbeAddOp(v, pLevel->inOp, pLevel->inP1, pLevel->inP2);
+    }
+    if( pLevel->iLeftJoin ){
+      int addr;
+      addr = sqlite3VdbeAddOp(v, OP_MemLoad, pLevel->iLeftJoin, 0);
+      sqlite3VdbeAddOp(v, OP_NotNull, 1, addr+4 + (pLevel->iCur>=0));
+      sqlite3VdbeAddOp(v, OP_NullRow, pTabList->a[i].iCursor, 0);
+      if( pLevel->iCur>=0 ){
+        sqlite3VdbeAddOp(v, OP_NullRow, pLevel->iCur, 0);
+      }
+      sqlite3VdbeAddOp(v, OP_Goto, 0, pLevel->top);
+    }
+  }
+  sqlite3VdbeResolveLabel(v, pWInfo->iBreak);
+  for(i=0; i<pTabList->nSrc; i++){
+    Table *pTab = pTabList->a[i].pTab;
+    assert( pTab!=0 );
+    if( pTab->isTransient || pTab->pSelect ) continue;
+    pLevel = &pWInfo->a[i];
+    sqlite3VdbeAddOp(v, OP_Close, pTabList->a[i].iCursor, 0);
+    if( pLevel->pIdx!=0 ){
+      sqlite3VdbeAddOp(v, OP_Close, pLevel->iCur, 0);
+    }
+  }
+  sqliteFree(pWInfo);
+  return;
+}