Adding upstream version 3.45.1.upstream/3.45.1

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2789 insertions, 0 deletions

diff --git a/src/wherecode.c b/src/wherecode.c
new file mode 100644
index 0000000..47ce36c
--- /dev/null
+++ b/src/wherecode.c
@@ -0,0 +1,2789 @@
+/*
+** 2015-06-06
+**
+** 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 file was split off from where.c on 2015-06-06 in order to reduce the
+** size of where.c and make it easier to edit.  This file contains the routines
+** that actually generate the bulk of the WHERE loop code.  The original where.c
+** file retains the code that does query planning and analysis.
+*/
+#include "sqliteInt.h"
+#include "whereInt.h"
+
+#ifndef SQLITE_OMIT_EXPLAIN
+
+/*
+** Return the name of the i-th column of the pIdx index.
+*/
+static const char *explainIndexColumnName(Index *pIdx, int i){
+  i = pIdx->aiColumn[i];
+  if( i==XN_EXPR ) return "<expr>";
+  if( i==XN_ROWID ) return "rowid";
+  return pIdx->pTable->aCol[i].zCnName;
+}
+
+/*
+** 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 */
+  Index *pIdx,                /* Index to read column names from */
+  int nTerm,                  /* Number of terms */
+  int iTerm,                  /* Zero-based index of first term. */
+  int bAnd,                   /* Non-zero to append " AND " */
+  const char *zOp             /* Name of the operator */
+){
+  int i;
+
+  assert( nTerm>=1 );
+  if( bAnd ) sqlite3_str_append(pStr, " AND ", 5);
+
+  if( nTerm>1 ) sqlite3_str_append(pStr, "(", 1);
+  for(i=0; i<nTerm; i++){
+    if( i ) sqlite3_str_append(pStr, ",", 1);
+    sqlite3_str_appendall(pStr, explainIndexColumnName(pIdx, iTerm+i));
+  }
+  if( nTerm>1 ) sqlite3_str_append(pStr, ")", 1);
+
+  sqlite3_str_append(pStr, zOp, 1);
+
+  if( nTerm>1 ) sqlite3_str_append(pStr, "(", 1);
+  for(i=0; i<nTerm; i++){
+    if( i ) sqlite3_str_append(pStr, ",", 1);
+    sqlite3_str_append(pStr, "?", 1);
+  }
+  if( nTerm>1 ) sqlite3_str_append(pStr, ")", 1);
+}
+
+/*
+** Argument pLevel describes a strategy for scanning table pTab. This
+** function appends text to pStr that describes the subset of table
+** rows scanned by the strategy in the form of an SQL expression.
+**
+** 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>?"
+*/
+static void explainIndexRange(StrAccum *pStr, WhereLoop *pLoop){
+  Index *pIndex = pLoop->u.btree.pIndex;
+  u16 nEq = pLoop->u.btree.nEq;
+  u16 nSkip = pLoop->nSkip;
+  int i, j;
+
+  if( nEq==0 && (pLoop->wsFlags&(WHERE_BTM_LIMIT|WHERE_TOP_LIMIT))==0 ) return;
+  sqlite3_str_append(pStr, " (", 2);
+  for(i=0; i<nEq; i++){
+    const char *z = explainIndexColumnName(pIndex, i);
+    if( i ) sqlite3_str_append(pStr, " AND ", 5);
+    sqlite3_str_appendf(pStr, i>=nSkip ? "%s=?" : "ANY(%s)", z);
+  }
+
+  j = i;
+  if( pLoop->wsFlags&WHERE_BTM_LIMIT ){
+    explainAppendTerm(pStr, pIndex, pLoop->u.btree.nBtm, j, i, ">");
+    i = 1;
+  }
+  if( pLoop->wsFlags&WHERE_TOP_LIMIT ){
+    explainAppendTerm(pStr, pIndex, pLoop->u.btree.nTop, j, i, "<");
+  }
+  sqlite3_str_append(pStr, ")", 1);
+}
+
+/*
+** This function is a no-op unless currently processing an EXPLAIN QUERY PLAN
+** command, or if stmt_scanstatus_v2() stats are enabled, or if SQLITE_DEBUG
+** was defined at compile-time. If it is not a no-op, a single OP_Explain
+** opcode is added to the output to describe the table scan strategy in pLevel.
+**
+** If an OP_Explain opcode is added to the VM, its address is returned.
+** Otherwise, if no OP_Explain is coded, zero is returned.
+*/
+int sqlite3WhereExplainOneScan(
+  Parse *pParse,                  /* Parse context */
+  SrcList *pTabList,              /* Table list this loop refers to */
+  WhereLevel *pLevel,             /* Scan to write OP_Explain opcode for */
+  u16 wctrlFlags                  /* Flags passed to sqlite3WhereBegin() */
+){
+  int ret = 0;
+#if !defined(SQLITE_DEBUG)
+  if( sqlite3ParseToplevel(pParse)->explain==2 || IS_STMT_SCANSTATUS(pParse->db) )
+#endif
+  {
+    SrcItem *pItem = &pTabList->a[pLevel->iFrom];
+    Vdbe *v = pParse->pVdbe;      /* VM being constructed */
+    sqlite3 *db = pParse->db;     /* Database handle */
+    int isSearch;                 /* True for a SEARCH. False for SCAN. */
+    WhereLoop *pLoop;             /* The controlling WhereLoop object */
+    u32 flags;                    /* Flags that describe this loop */
+    char *zMsg;                   /* Text to add to EQP output */
+    StrAccum str;                 /* EQP output string */
+    char zBuf[100];               /* Initial space for EQP output string */
+
+    pLoop = pLevel->pWLoop;
+    flags = pLoop->wsFlags;
+    if( (flags&WHERE_MULTI_OR) || (wctrlFlags&WHERE_OR_SUBCLAUSE) ) return 0;
+
+    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));
+
+    sqlite3StrAccumInit(&str, db, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH);
+    str.printfFlags = SQLITE_PRINTF_INTERNAL;
+    sqlite3_str_appendf(&str, "%s %S", isSearch ? "SEARCH" : "SCAN", pItem);
+    if( (flags & (WHERE_IPK|WHERE_VIRTUALTABLE))==0 ){
+      const char *zFmt = 0;
+      Index *pIdx;
+
+      assert( pLoop->u.btree.pIndex!=0 );
+      pIdx = pLoop->u.btree.pIndex;
+      assert( !(flags&WHERE_AUTO_INDEX) || (flags&WHERE_IDX_ONLY) );
+      if( !HasRowid(pItem->pTab) && IsPrimaryKeyIndex(pIdx) ){
+        if( isSearch ){
+          zFmt = "PRIMARY KEY";
+        }
+      }else if( flags & WHERE_PARTIALIDX ){
+        zFmt = "AUTOMATIC PARTIAL COVERING INDEX";
+      }else if( flags & WHERE_AUTO_INDEX ){
+        zFmt = "AUTOMATIC COVERING INDEX";
+      }else if( flags & WHERE_IDX_ONLY ){
+        zFmt = "COVERING INDEX %s";
+      }else{
+        zFmt = "INDEX %s";
+      }
+      if( zFmt ){
+        sqlite3_str_append(&str, " USING ", 7);
+        sqlite3_str_appendf(&str, zFmt, pIdx->zName);
+        explainIndexRange(&str, pLoop);
+      }
+    }else if( (flags & WHERE_IPK)!=0 && (flags & WHERE_CONSTRAINT)!=0 ){
+      char cRangeOp;
+#if 0  /* Better output, but breaks many tests */
+      const Table *pTab = pItem->pTab;
+      const char *zRowid = pTab->iPKey>=0 ? pTab->aCol[pTab->iPKey].zCnName:
+                              "rowid";
+#else
+      const char *zRowid = "rowid";
+#endif
+      sqlite3_str_appendf(&str, " USING INTEGER PRIMARY KEY (%s", zRowid);
+      if( flags&(WHERE_COLUMN_EQ|WHERE_COLUMN_IN) ){
+        cRangeOp = '=';
+      }else if( (flags&WHERE_BOTH_LIMIT)==WHERE_BOTH_LIMIT ){
+        sqlite3_str_appendf(&str, ">? AND %s", zRowid);
+        cRangeOp = '<';
+      }else if( flags&WHERE_BTM_LIMIT ){
+        cRangeOp = '>';
+      }else{
+        assert( flags&WHERE_TOP_LIMIT);
+        cRangeOp = '<';
+      }
+      sqlite3_str_appendf(&str, "%c?)", cRangeOp);
+    }
+#ifndef SQLITE_OMIT_VIRTUALTABLE
+    else if( (flags & WHERE_VIRTUALTABLE)!=0 ){
+      sqlite3_str_appendf(&str, " VIRTUAL TABLE INDEX %d:%s",
+                  pLoop->u.vtab.idxNum, pLoop->u.vtab.idxStr);
+    }
+#endif
+    if( pItem->fg.jointype & JT_LEFT ){
+      sqlite3_str_appendf(&str, " LEFT-JOIN");
+    }
+#ifdef SQLITE_EXPLAIN_ESTIMATED_ROWS
+    if( pLoop->nOut>=10 ){
+      sqlite3_str_appendf(&str, " (~%llu rows)",
+             sqlite3LogEstToInt(pLoop->nOut));
+    }else{
+      sqlite3_str_append(&str, " (~1 row)", 9);
+    }
+#endif
+    zMsg = sqlite3StrAccumFinish(&str);
+    sqlite3ExplainBreakpoint("",zMsg);
+    ret = sqlite3VdbeAddOp4(v, OP_Explain, sqlite3VdbeCurrentAddr(v),
+                            pParse->addrExplain, 0, zMsg,P4_DYNAMIC);
+  }
+  return ret;
+}
+
+/*
+** Add a single OP_Explain opcode that describes a Bloom filter.
+**
+** Or if not processing EXPLAIN QUERY PLAN and not in a SQLITE_DEBUG and/or
+** SQLITE_ENABLE_STMT_SCANSTATUS build, then OP_Explain opcodes are not
+** required and this routine is a no-op.
+**
+** If an OP_Explain opcode is added to the VM, its address is returned.
+** Otherwise, if no OP_Explain is coded, zero is returned.
+*/
+int sqlite3WhereExplainBloomFilter(
+  const Parse *pParse,               /* Parse context */
+  const WhereInfo *pWInfo,           /* WHERE clause */
+  const WhereLevel *pLevel           /* Bloom filter on this level */
+){
+  int ret = 0;
+  SrcItem *pItem = &pWInfo->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 i;                        /* Loop counter */
+  WhereLoop *pLoop;             /* The where loop */
+  StrAccum str;                 /* EQP output string */
+  char zBuf[100];               /* Initial space for EQP output string */
+
+  sqlite3StrAccumInit(&str, db, zBuf, sizeof(zBuf), SQLITE_MAX_LENGTH);
+  str.printfFlags = SQLITE_PRINTF_INTERNAL;
+  sqlite3_str_appendf(&str, "BLOOM FILTER ON %S (", pItem);
+  pLoop = pLevel->pWLoop;
+  if( pLoop->wsFlags & WHERE_IPK ){
+    const Table *pTab = pItem->pTab;
+    if( pTab->iPKey>=0 ){
+      sqlite3_str_appendf(&str, "%s=?", pTab->aCol[pTab->iPKey].zCnName);
+    }else{
+      sqlite3_str_appendf(&str, "rowid=?");
+    }
+  }else{
+    for(i=pLoop->nSkip; i<pLoop->u.btree.nEq; i++){
+      const char *z = explainIndexColumnName(pLoop->u.btree.pIndex, i);
+      if( i>pLoop->nSkip ) sqlite3_str_append(&str, " AND ", 5);
+      sqlite3_str_appendf(&str, "%s=?", z);
+    }
+  }
+  sqlite3_str_append(&str, ")", 1);
+  zMsg = sqlite3StrAccumFinish(&str);
+  ret = sqlite3VdbeAddOp4(v, OP_Explain, sqlite3VdbeCurrentAddr(v),
+                          pParse->addrExplain, 0, zMsg,P4_DYNAMIC);
+
+  sqlite3VdbeScanStatus(v, sqlite3VdbeCurrentAddr(v)-1, 0, 0, 0, 0);
+  return ret;
+}
+#endif /* SQLITE_OMIT_EXPLAIN */
+
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+/*
+** Configure the VM passed as the first argument with an
+** sqlite3_stmt_scanstatus() entry corresponding to the scan used to
+** implement level pLvl. Argument pSrclist is a pointer to the FROM
+** clause that the scan reads data from.
+**
+** If argument addrExplain is not 0, it must be the address of an
+** OP_Explain instruction that describes the same loop.
+*/
+void sqlite3WhereAddScanStatus(
+  Vdbe *v,                        /* Vdbe to add scanstatus entry to */
+  SrcList *pSrclist,              /* FROM clause pLvl reads data from */
+  WhereLevel *pLvl,               /* Level to add scanstatus() entry for */
+  int addrExplain                 /* Address of OP_Explain (or 0) */
+){
+  if( IS_STMT_SCANSTATUS( sqlite3VdbeDb(v) ) ){
+    const char *zObj = 0;
+    WhereLoop *pLoop = pLvl->pWLoop;
+    int wsFlags = pLoop->wsFlags;
+    int viaCoroutine = 0;
+
+    if( (wsFlags & WHERE_VIRTUALTABLE)==0  &&  pLoop->u.btree.pIndex!=0 ){
+      zObj = pLoop->u.btree.pIndex->zName;
+    }else{
+      zObj = pSrclist->a[pLvl->iFrom].zName;
+      viaCoroutine = pSrclist->a[pLvl->iFrom].fg.viaCoroutine;
+    }
+    sqlite3VdbeScanStatus(
+        v, addrExplain, pLvl->addrBody, pLvl->addrVisit, pLoop->nOut, zObj
+    );
+
+    if( viaCoroutine==0 ){
+      if( (wsFlags & (WHERE_MULTI_OR|WHERE_AUTO_INDEX))==0 ){
+        sqlite3VdbeScanStatusRange(v, addrExplain, -1, pLvl->iTabCur);
+      }
+      if( wsFlags & WHERE_INDEXED ){
+        sqlite3VdbeScanStatusRange(v, addrExplain, -1, pLvl->iIdxCur);
+      }
+    }else{
+      int addr = pSrclist->a[pLvl->iFrom].addrFillSub;
+      VdbeOp *pOp = sqlite3VdbeGetOp(v, addr-1);
+      assert( sqlite3VdbeDb(v)->mallocFailed || pOp->opcode==OP_InitCoroutine );
+      assert( sqlite3VdbeDb(v)->mallocFailed || pOp->p2>addr );
+      sqlite3VdbeScanStatusRange(v, addrExplain, addr, pOp->p2-1);
+    }
+  }
+}
+#endif
+
+
+/*
+** 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.
+**
+** If all the children of a term are disabled, then that term is also
+** automatically disabled.  In this way, terms get disabled if derived
+** virtual terms are tested first.  For example:
+**
+**      x GLOB 'abc*' AND x>='abc' AND x<'acd'
+**      \___________/     \______/     \_____/
+**         parent          child1       child2
+**
+** Only the parent term was in the original WHERE clause.  The child1
+** and child2 terms were added by the LIKE optimization.  If both of
+** the virtual child terms are valid, then testing of the parent can be
+** skipped.
+**
+** Usually the parent term is marked as TERM_CODED.  But if the parent
+** term was originally TERM_LIKE, then the parent gets TERM_LIKECOND instead.
+** The TERM_LIKECOND marking indicates that the term should be coded inside
+** a conditional such that is only evaluated on the second pass of a
+** LIKE-optimization loop, when scanning BLOBs instead of strings.
+*/
+static void disableTerm(WhereLevel *pLevel, WhereTerm *pTerm){
+  int nLoop = 0;
+  assert( pTerm!=0 );
+  while( (pTerm->wtFlags & TERM_CODED)==0
+      && (pLevel->iLeftJoin==0 || ExprHasProperty(pTerm->pExpr, EP_OuterON))
+      && (pLevel->notReady & pTerm->prereqAll)==0
+  ){
+    if( nLoop && (pTerm->wtFlags & TERM_LIKE)!=0 ){
+      pTerm->wtFlags |= TERM_LIKECOND;
+    }else{
+      pTerm->wtFlags |= TERM_CODED;
+    }
+#ifdef WHERETRACE_ENABLED
+    if( (sqlite3WhereTrace & 0x4001)==0x4001 ){
+      sqlite3DebugPrintf("DISABLE-");
+      sqlite3WhereTermPrint(pTerm, (int)(pTerm - (pTerm->pWC->a)));
+    }
+#endif
+    if( pTerm->iParent<0 ) break;
+    pTerm = &pTerm->pWC->a[pTerm->iParent];
+    assert( pTerm!=0 );
+    pTerm->nChild--;
+    if( pTerm->nChild!=0 ) break;
+    nLoop++;
+  }
+}
+
+/*
+** Code an OP_Affinity opcode to apply the column affinity string zAff
+** to the n registers starting at base.
+**
+** As an optimization, SQLITE_AFF_BLOB and 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_BLOB or 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_BLOB and SQLITE_AFF_NONE
+  ** entries at the beginning and end of the affinity string.
+  */
+  assert( SQLITE_AFF_NONE<SQLITE_AFF_BLOB );
+  while( n>0 && zAff[0]<=SQLITE_AFF_BLOB ){
+    n--;
+    base++;
+    zAff++;
+  }
+  while( n>1 && zAff[n-1]<=SQLITE_AFF_BLOB ){
+    n--;
+  }
+
+  /* Code the OP_Affinity opcode if there is anything left to do. */
+  if( n>0 ){
+    sqlite3VdbeAddOp4(v, OP_Affinity, base, n, 0, zAff, n);
+  }
+}
+
+/*
+** Expression pRight, which is the RHS of a comparison operation, is
+** either a vector of n elements or, if n==1, a scalar expression.
+** Before the comparison operation, affinity zAff is to be applied
+** to the pRight values. This function modifies characters within the
+** affinity string to SQLITE_AFF_BLOB if either:
+**
+**   * the comparison will be performed with no affinity, or
+**   * the affinity change in zAff is guaranteed not to change the value.
+*/
+static void updateRangeAffinityStr(
+  Expr *pRight,                   /* RHS of comparison */
+  int n,                          /* Number of vector elements in comparison */
+  char *zAff                      /* Affinity string to modify */
+){
+  int i;
+  for(i=0; i<n; i++){
+    Expr *p = sqlite3VectorFieldSubexpr(pRight, i);
+    if( sqlite3CompareAffinity(p, zAff[i])==SQLITE_AFF_BLOB
+     || sqlite3ExprNeedsNoAffinityChange(p, zAff[i])
+    ){
+      zAff[i] = SQLITE_AFF_BLOB;
+    }
+  }
+}
+
+
+/*
+** pX is an expression of the form:  (vector) IN (SELECT ...)
+** In other words, it is a vector IN operator with a SELECT clause on the
+** LHS.  But not all terms in the vector are indexable and the terms might
+** not be in the correct order for indexing.
+**
+** This routine makes a copy of the input pX expression and then adjusts
+** the vector on the LHS with corresponding changes to the SELECT so that
+** the vector contains only index terms and those terms are in the correct
+** order.  The modified IN expression is returned.  The caller is responsible
+** for deleting the returned expression.
+**
+** Example:
+**
+**    CREATE TABLE t1(a,b,c,d,e,f);
+**    CREATE INDEX t1x1 ON t1(e,c);
+**    SELECT * FROM t1 WHERE (a,b,c,d,e) IN (SELECT v,w,x,y,z FROM t2)
+**                           \_______________________________________/
+**                                     The pX expression
+**
+** Since only columns e and c can be used with the index, in that order,
+** the modified IN expression that is returned will be:
+**
+**        (e,c) IN (SELECT z,x FROM t2)
+**
+** The reduced pX is different from the original (obviously) and thus is
+** only used for indexing, to improve performance.  The original unaltered
+** IN expression must also be run on each output row for correctness.
+*/
+static Expr *removeUnindexableInClauseTerms(
+  Parse *pParse,        /* The parsing context */
+  int iEq,              /* Look at loop terms starting here */
+  WhereLoop *pLoop,     /* The current loop */
+  Expr *pX              /* The IN expression to be reduced */
+){
+  sqlite3 *db = pParse->db;
+  Select *pSelect;            /* Pointer to the SELECT on the RHS */
+  Expr *pNew;
+  pNew = sqlite3ExprDup(db, pX, 0);
+  if( db->mallocFailed==0 ){
+    for(pSelect=pNew->x.pSelect; pSelect; pSelect=pSelect->pPrior){
+      ExprList *pOrigRhs;         /* Original unmodified RHS */
+      ExprList *pOrigLhs = 0;     /* Original unmodified LHS */
+      ExprList *pRhs = 0;         /* New RHS after modifications */
+      ExprList *pLhs = 0;         /* New LHS after mods */
+      int i;                      /* Loop counter */
+
+      assert( ExprUseXSelect(pNew) );
+      pOrigRhs = pSelect->pEList;
+      assert( pNew->pLeft!=0 );
+      assert( ExprUseXList(pNew->pLeft) );
+      if( pSelect==pNew->x.pSelect ){
+        pOrigLhs = pNew->pLeft->x.pList;
+      }
+      for(i=iEq; i<pLoop->nLTerm; i++){
+        if( pLoop->aLTerm[i]->pExpr==pX ){
+          int iField;
+          assert( (pLoop->aLTerm[i]->eOperator & (WO_OR|WO_AND))==0 );
+          iField = pLoop->aLTerm[i]->u.x.iField - 1;
+          if( pOrigRhs->a[iField].pExpr==0 ) continue; /* Duplicate PK column */
+          pRhs = sqlite3ExprListAppend(pParse, pRhs, pOrigRhs->a[iField].pExpr);
+          pOrigRhs->a[iField].pExpr = 0;
+          if( pOrigLhs ){
+            assert( pOrigLhs->a[iField].pExpr!=0 );
+            pLhs = sqlite3ExprListAppend(pParse,pLhs,pOrigLhs->a[iField].pExpr);
+            pOrigLhs->a[iField].pExpr = 0;
+          }
+        }
+      }
+      sqlite3ExprListDelete(db, pOrigRhs);
+      if( pOrigLhs ){
+        sqlite3ExprListDelete(db, pOrigLhs);
+        pNew->pLeft->x.pList = pLhs;
+      }
+      pSelect->pEList = pRhs;
+      if( pLhs && pLhs->nExpr==1 ){
+        /* Take care here not to generate a TK_VECTOR containing only a
+        ** single value. Since the parser never creates such a vector, some
+        ** of the subroutines do not handle this case.  */
+        Expr *p = pLhs->a[0].pExpr;
+        pLhs->a[0].pExpr = 0;
+        sqlite3ExprDelete(db, pNew->pLeft);
+        pNew->pLeft = p;
+      }
+      if( pSelect->pOrderBy ){
+        /* If the SELECT statement has an ORDER BY clause, zero the
+        ** iOrderByCol variables. These are set to non-zero when an
+        ** ORDER BY term exactly matches one of the terms of the
+        ** result-set. Since the result-set of the SELECT statement may
+        ** have been modified or reordered, these variables are no longer
+        ** set correctly.  Since setting them is just an optimization,
+        ** it's easiest just to zero them here.  */
+        ExprList *pOrderBy = pSelect->pOrderBy;
+        for(i=0; i<pOrderBy->nExpr; i++){
+          pOrderBy->a[i].u.x.iOrderByCol = 0;
+        }
+      }
+
+#if 0
+      printf("For indexing, change the IN expr:\n");
+      sqlite3TreeViewExpr(0, pX, 0);
+      printf("Into:\n");
+      sqlite3TreeViewExpr(0, pNew, 0);
+#endif
+    }
+  }
+  return pNew;
+}
+
+
+/*
+** 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 a register, the index
+** of which is returned.  An attempt is made store the result in iTarget but
+** this is only guaranteed for TK_ISNULL and TK_IN constraints.  If the
+** constraint is a TK_EQ or TK_IS, then the current value might be left in
+** some other register and it is the caller's responsibility to compensate.
+**
+** For a constraint of the form X=expr, the expression is evaluated in
+** straight-line code.  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( pLevel->pWLoop->aLTerm[iEq]==pTerm );
+  assert( iTarget>0 );
+  if( pX->op==TK_EQ || pX->op==TK_IS ){
+    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 = IN_INDEX_NOOP;
+    int iTab;
+    struct InLoop *pIn;
+    WhereLoop *pLoop = pLevel->pWLoop;
+    int i;
+    int nEq = 0;
+    int *aiMap = 0;
+
+    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;
+
+    for(i=0; i<iEq; i++){
+      if( pLoop->aLTerm[i] && pLoop->aLTerm[i]->pExpr==pX ){
+        disableTerm(pLevel, pTerm);
+        return iTarget;
+      }
+    }
+    for(i=iEq;i<pLoop->nLTerm; i++){
+      assert( pLoop->aLTerm[i]!=0 );
+      if( pLoop->aLTerm[i]->pExpr==pX ) nEq++;
+    }
+
+    iTab = 0;
+    if( !ExprUseXSelect(pX) || pX->x.pSelect->pEList->nExpr==1 ){
+      eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0, 0, &iTab);
+    }else{
+      Expr *pExpr = pTerm->pExpr;
+      if( pExpr->iTable==0 || !ExprHasProperty(pExpr, EP_Subrtn) ){
+        sqlite3 *db = pParse->db;
+        pX = removeUnindexableInClauseTerms(pParse, iEq, pLoop, pX);
+        if( !db->mallocFailed ){
+          aiMap = (int*)sqlite3DbMallocZero(pParse->db, sizeof(int)*nEq);
+          eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0, aiMap,&iTab);
+          pExpr->iTable = iTab;
+        }
+        sqlite3ExprDelete(db, pX);
+      }else{
+        int n = sqlite3ExprVectorSize(pX->pLeft);
+        aiMap = (int*)sqlite3DbMallocZero(pParse->db, sizeof(int)*MAX(nEq,n));
+        eType = sqlite3FindInIndex(pParse, pX, IN_INDEX_LOOP, 0, aiMap, &iTab);
+      }
+      pX = pExpr;
+    }
+
+    if( eType==IN_INDEX_INDEX_DESC ){
+      testcase( bRev );
+      bRev = !bRev;
+    }
+    sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iTab, 0);
+    VdbeCoverageIf(v, bRev);
+    VdbeCoverageIf(v, !bRev);
+
+    assert( (pLoop->wsFlags & WHERE_MULTI_OR)==0 );
+    pLoop->wsFlags |= WHERE_IN_ABLE;
+    if( pLevel->u.in.nIn==0 ){
+      pLevel->addrNxt = sqlite3VdbeMakeLabel(pParse);
+    }
+    if( iEq>0 && (pLoop->wsFlags & WHERE_IN_SEEKSCAN)==0 ){
+      pLoop->wsFlags |= WHERE_IN_EARLYOUT;
+    }
+
+    i = pLevel->u.in.nIn;
+    pLevel->u.in.nIn += nEq;
+    pLevel->u.in.aInLoop =
+       sqlite3WhereRealloc(pTerm->pWC->pWInfo,
+                           pLevel->u.in.aInLoop,
+                           sizeof(pLevel->u.in.aInLoop[0])*pLevel->u.in.nIn);
+    pIn = pLevel->u.in.aInLoop;
+    if( pIn ){
+      int iMap = 0;               /* Index in aiMap[] */
+      pIn += i;
+      for(i=iEq;i<pLoop->nLTerm; i++){
+        if( pLoop->aLTerm[i]->pExpr==pX ){
+          int iOut = iReg + i - iEq;
+          if( eType==IN_INDEX_ROWID ){
+            pIn->addrInTop = sqlite3VdbeAddOp2(v, OP_Rowid, iTab, iOut);
+          }else{
+            int iCol = aiMap ? aiMap[iMap++] : 0;
+            pIn->addrInTop = sqlite3VdbeAddOp3(v,OP_Column,iTab, iCol, iOut);
+          }
+          sqlite3VdbeAddOp1(v, OP_IsNull, iOut); VdbeCoverage(v);
+          if( i==iEq ){
+            pIn->iCur = iTab;
+            pIn->eEndLoopOp = bRev ? OP_Prev : OP_Next;
+            if( iEq>0 ){
+              pIn->iBase = iReg - i;
+              pIn->nPrefix = i;
+            }else{
+              pIn->nPrefix = 0;
+            }
+          }else{
+            pIn->eEndLoopOp = OP_Noop;
+          }
+          pIn++;
+        }
+      }
+      testcase( iEq>0
+                && (pLoop->wsFlags & WHERE_IN_SEEKSCAN)==0
+                && (pLoop->wsFlags & WHERE_VIRTUALTABLE)!=0 );
+      if( iEq>0
+       && (pLoop->wsFlags & (WHERE_IN_SEEKSCAN|WHERE_VIRTUALTABLE))==0
+      ){
+        sqlite3VdbeAddOp3(v, OP_SeekHit, pLevel->iIdxCur, 0, iEq);
+      }
+    }else{
+      pLevel->u.in.nIn = 0;
+    }
+    sqlite3DbFree(pParse->db, aiMap);
+#endif
+  }
+
+  /* As an optimization, try to disable the WHERE clause term that is
+  ** driving the index as it will always be true.  The correct answer is
+  ** obtained regardless, but we might get the answer with fewer CPU cycles
+  ** by omitting the term.
+  **
+  ** But do not disable the term unless we are certain that the term is
+  ** not a transitive constraint.  For an example of where that does not
+  ** work, see https://sqlite.org/forum/forumpost/eb8613976a (2021-05-04)
+  */
+  if( (pLevel->pWLoop->wsFlags & WHERE_TRANSCONS)==0
+   || (pTerm->eOperator & WO_EQUIV)==0
+  ){
+    disableTerm(pLevel, pTerm);
+  }
+
+  return iReg;
+}
+
+/*
+** Generate code that will evaluate all == and IN constraints for an
+** index scan.
+**
+** 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.
+**
+** The nExtraReg parameter is 0 or 1.  It is 0 if all WHERE clause constraints
+** are == or IN and are covered by the nEq.  nExtraReg is 1 if there is
+** an inequality constraint (such as the "c>=5 AND c<10" in the example) that
+** occurs after the nEq quality constraints.
+**
+** This routine allocates a range of nEq+nExtraReg memory cells and returns
+** the index of the first memory cell in that range. The code that
+** calls this routine will use that memory range to store keys for
+** start and termination conditions of the loop.
+** 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 BLOB or NONE affinity are set to
+** SQLITE_AFF_BLOB. 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 BLOB/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_BLOB.
+*/
+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 */
+){
+  u16 nEq;                      /* The number of == or IN constraints to code */
+  u16 nSkip;                    /* Number of left-most columns to skip */
+  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;
+  nSkip = pLoop->nSkip;
+  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 = nEq + nExtraReg;
+  pParse->nMem += nReg;
+
+  zAff = sqlite3DbStrDup(pParse->db,sqlite3IndexAffinityStr(pParse->db,pIdx));
+  assert( zAff!=0 || pParse->db->mallocFailed );
+
+  if( nSkip ){
+    int iIdxCur = pLevel->iIdxCur;
+    sqlite3VdbeAddOp3(v, OP_Null, 0, regBase, regBase+nSkip-1);
+    sqlite3VdbeAddOp1(v, (bRev?OP_Last:OP_Rewind), iIdxCur);
+    VdbeCoverageIf(v, bRev==0);
+    VdbeCoverageIf(v, bRev!=0);
+    VdbeComment((v, "begin skip-scan on %s", pIdx->zName));
+    j = sqlite3VdbeAddOp0(v, OP_Goto);
+    assert( pLevel->addrSkip==0 );
+    pLevel->addrSkip = sqlite3VdbeAddOp4Int(v, (bRev?OP_SeekLT:OP_SeekGT),
+                            iIdxCur, 0, regBase, nSkip);
+    VdbeCoverageIf(v, bRev==0);
+    VdbeCoverageIf(v, bRev!=0);
+    sqlite3VdbeJumpHere(v, j);
+    for(j=0; j<nSkip; j++){
+      sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, j, regBase+j);
+      testcase( pIdx->aiColumn[j]==XN_EXPR );
+      VdbeComment((v, "%s", explainIndexColumnName(pIdx, j)));
+    }
+  }   
+
+  /* Evaluate the equality constraints
+  */
+  assert( zAff==0 || (int)strlen(zAff)>=nEq );
+  for(j=nSkip; j<nEq; j++){
+    int r1;
+    pTerm = pLoop->aLTerm[j];
+    assert( pTerm!=0 );
+    /* The following testcase is 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_Copy, r1, regBase+j);
+      }
+    }
+    if( pTerm->eOperator & WO_IN ){
+      if( pTerm->pExpr->flags & EP_xIsSelect ){
+        /* No affinity ever needs to be (or should be) applied to a value
+        ** from the RHS of an "? IN (SELECT ...)" expression. The
+        ** sqlite3FindInIndex() routine has already ensured that the
+        ** affinity of the comparison has been applied to the value.  */
+        if( zAff ) zAff[j] = SQLITE_AFF_BLOB;
+      }
+    }else if( (pTerm->eOperator & WO_ISNULL)==0 ){
+      Expr *pRight = pTerm->pExpr->pRight;
+      if( (pTerm->wtFlags & TERM_IS)==0 && sqlite3ExprCanBeNull(pRight) ){
+        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+j, pLevel->addrBrk);
+        VdbeCoverage(v);
+      }
+      if( pParse->nErr==0 ){
+        assert( pParse->db->mallocFailed==0 );
+        if( sqlite3CompareAffinity(pRight, zAff[j])==SQLITE_AFF_BLOB ){
+          zAff[j] = SQLITE_AFF_BLOB;
+        }
+        if( sqlite3ExprNeedsNoAffinityChange(pRight, zAff[j]) ){
+          zAff[j] = SQLITE_AFF_BLOB;
+        }
+      }
+    }
+  }
+  *pzAff = zAff;
+  return regBase;
+}
+
+#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+/*
+** If the most recently coded instruction is a constant range constraint
+** (a string literal) that originated from the LIKE optimization, then
+** set P3 and P5 on the OP_String opcode so that the string will be cast
+** to a BLOB at appropriate times.
+**
+** The LIKE optimization trys to evaluate "x LIKE 'abc%'" as a range
+** expression: "x>='ABC' AND x<'abd'".  But this requires that the range
+** scan loop run twice, once for strings and a second time for BLOBs.
+** The OP_String opcodes on the second pass convert the upper and lower
+** bound string constants to blobs.  This routine makes the necessary changes
+** to the OP_String opcodes for that to happen.
+**
+** Except, of course, if SQLITE_LIKE_DOESNT_MATCH_BLOBS is defined, then
+** only the one pass through the string space is required, so this routine
+** becomes a no-op.
+*/
+static void whereLikeOptimizationStringFixup(
+  Vdbe *v,                /* prepared statement under construction */
+  WhereLevel *pLevel,     /* The loop that contains the LIKE operator */
+  WhereTerm *pTerm        /* The upper or lower bound just coded */
+){
+  if( pTerm->wtFlags & TERM_LIKEOPT ){
+    VdbeOp *pOp;
+    assert( pLevel->iLikeRepCntr>0 );
+    pOp = sqlite3VdbeGetLastOp(v);
+    assert( pOp!=0 );
+    assert( pOp->opcode==OP_String8
+            || pTerm->pWC->pWInfo->pParse->db->mallocFailed );
+    pOp->p3 = (int)(pLevel->iLikeRepCntr>>1);  /* Register holding counter */
+    pOp->p5 = (u8)(pLevel->iLikeRepCntr&1);    /* ASC or DESC */
+  }
+}
+#else
+# define whereLikeOptimizationStringFixup(A,B,C)
+#endif
+
+#ifdef SQLITE_ENABLE_CURSOR_HINTS
+/*
+** Information is passed from codeCursorHint() down to individual nodes of
+** the expression tree (by sqlite3WalkExpr()) using an instance of this
+** structure.
+*/
+struct CCurHint {
+  int iTabCur;    /* Cursor for the main table */
+  int iIdxCur;    /* Cursor for the index, if pIdx!=0.  Unused otherwise */
+  Index *pIdx;    /* The index used to access the table */
+};
+
+/*
+** This function is called for every node of an expression that is a candidate
+** for a cursor hint on an index cursor.  For TK_COLUMN nodes that reference
+** the table CCurHint.iTabCur, verify that the same column can be
+** accessed through the index.  If it cannot, then set pWalker->eCode to 1.
+*/
+static int codeCursorHintCheckExpr(Walker *pWalker, Expr *pExpr){
+  struct CCurHint *pHint = pWalker->u.pCCurHint;
+  assert( pHint->pIdx!=0 );
+  if( pExpr->op==TK_COLUMN
+   && pExpr->iTable==pHint->iTabCur
+   && sqlite3TableColumnToIndex(pHint->pIdx, pExpr->iColumn)<0
+  ){
+    pWalker->eCode = 1;
+  }
+  return WRC_Continue;
+}
+
+/*
+** Test whether or not expression pExpr, which was part of a WHERE clause,
+** should be included in the cursor-hint for a table that is on the rhs
+** of a LEFT JOIN. Set Walker.eCode to non-zero before returning if the
+** expression is not suitable.
+**
+** An expression is unsuitable if it might evaluate to non NULL even if
+** a TK_COLUMN node that does affect the value of the expression is set
+** to NULL. For example:
+**
+**   col IS NULL
+**   col IS NOT NULL
+**   coalesce(col, 1)
+**   CASE WHEN col THEN 0 ELSE 1 END
+*/
+static int codeCursorHintIsOrFunction(Walker *pWalker, Expr *pExpr){
+  if( pExpr->op==TK_IS
+   || pExpr->op==TK_ISNULL || pExpr->op==TK_ISNOT
+   || pExpr->op==TK_NOTNULL || pExpr->op==TK_CASE
+  ){
+    pWalker->eCode = 1;
+  }else if( pExpr->op==TK_FUNCTION ){
+    int d1;
+    char d2[4];
+    if( 0==sqlite3IsLikeFunction(pWalker->pParse->db, pExpr, &d1, d2) ){
+      pWalker->eCode = 1;
+    }
+  }
+
+  return WRC_Continue;
+}
+
+
+/*
+** This function is called on every node of an expression tree used as an
+** argument to the OP_CursorHint instruction. If the node is a TK_COLUMN
+** that accesses any table other than the one identified by
+** CCurHint.iTabCur, then do the following:
+**
+**   1) allocate a register and code an OP_Column instruction to read
+**      the specified column into the new register, and
+**
+**   2) transform the expression node to a TK_REGISTER node that reads
+**      from the newly populated register.
+**
+** Also, if the node is a TK_COLUMN that does access the table identified
+** by pCCurHint.iTabCur, and an index is being used (which we will
+** know because CCurHint.pIdx!=0) then transform the TK_COLUMN into
+** an access of the index rather than the original table.
+*/
+static int codeCursorHintFixExpr(Walker *pWalker, Expr *pExpr){
+  int rc = WRC_Continue;
+  int reg;
+  struct CCurHint *pHint = pWalker->u.pCCurHint;
+  if( pExpr->op==TK_COLUMN ){
+    if( pExpr->iTable!=pHint->iTabCur ){
+      reg = ++pWalker->pParse->nMem;   /* Register for column value */
+      reg = sqlite3ExprCodeTarget(pWalker->pParse, pExpr, reg);
+      pExpr->op = TK_REGISTER;
+      pExpr->iTable = reg;
+    }else if( pHint->pIdx!=0 ){
+      pExpr->iTable = pHint->iIdxCur;
+      pExpr->iColumn = sqlite3TableColumnToIndex(pHint->pIdx, pExpr->iColumn);
+      assert( pExpr->iColumn>=0 );
+    }
+  }else if( pExpr->pAggInfo ){
+    rc = WRC_Prune;
+    reg = ++pWalker->pParse->nMem;   /* Register for column value */
+    reg = sqlite3ExprCodeTarget(pWalker->pParse, pExpr, reg);
+    pExpr->op = TK_REGISTER;
+    pExpr->iTable = reg;
+  }else if( pExpr->op==TK_TRUEFALSE ){
+    /* Do not walk disabled expressions.  tag-20230504-1 */
+    return WRC_Prune;
+  }
+  return rc;
+}
+
+/*
+** Insert an OP_CursorHint instruction if it is appropriate to do so.
+*/
+static void codeCursorHint(
+  SrcItem *pTabItem,  /* FROM clause item */
+  WhereInfo *pWInfo,    /* The where clause */
+  WhereLevel *pLevel,   /* Which loop to provide hints for */
+  WhereTerm *pEndRange  /* Hint this end-of-scan boundary term if not NULL */
+){
+  Parse *pParse = pWInfo->pParse;
+  sqlite3 *db = pParse->db;
+  Vdbe *v = pParse->pVdbe;
+  Expr *pExpr = 0;
+  WhereLoop *pLoop = pLevel->pWLoop;
+  int iCur;
+  WhereClause *pWC;
+  WhereTerm *pTerm;
+  int i, j;
+  struct CCurHint sHint;
+  Walker sWalker;
+
+  if( OptimizationDisabled(db, SQLITE_CursorHints) ) return;
+  iCur = pLevel->iTabCur;
+  assert( iCur==pWInfo->pTabList->a[pLevel->iFrom].iCursor );
+  sHint.iTabCur = iCur;
+  sHint.iIdxCur = pLevel->iIdxCur;
+  sHint.pIdx = pLoop->u.btree.pIndex;
+  memset(&sWalker, 0, sizeof(sWalker));
+  sWalker.pParse = pParse;
+  sWalker.u.pCCurHint = &sHint;
+  pWC = &pWInfo->sWC;
+  for(i=0; i<pWC->nBase; i++){
+    pTerm = &pWC->a[i];
+    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
+    if( pTerm->prereqAll & pLevel->notReady ) continue;
+
+    /* Any terms specified as part of the ON(...) clause for any LEFT
+    ** JOIN for which the current table is not the rhs are omitted
+    ** from the cursor-hint.
+    **
+    ** If this table is the rhs of a LEFT JOIN, "IS" or "IS NULL" terms
+    ** that were specified as part of the WHERE clause must be excluded.
+    ** This is to address the following:
+    **
+    **   SELECT ... t1 LEFT JOIN t2 ON (t1.a=t2.b) WHERE t2.c IS NULL;
+    **
+    ** Say there is a single row in t2 that matches (t1.a=t2.b), but its
+    ** t2.c values is not NULL. If the (t2.c IS NULL) constraint is
+    ** pushed down to the cursor, this row is filtered out, causing
+    ** SQLite to synthesize a row of NULL values. Which does match the
+    ** WHERE clause, and so the query returns a row. Which is incorrect.
+    **
+    ** For the same reason, WHERE terms such as:
+    **
+    **   WHERE 1 = (t2.c IS NULL)
+    **
+    ** are also excluded. See codeCursorHintIsOrFunction() for details.
+    */
+    if( pTabItem->fg.jointype & JT_LEFT ){
+      Expr *pExpr = pTerm->pExpr;
+      if( !ExprHasProperty(pExpr, EP_OuterON)
+       || pExpr->w.iJoin!=pTabItem->iCursor
+      ){
+        sWalker.eCode = 0;
+        sWalker.xExprCallback = codeCursorHintIsOrFunction;
+        sqlite3WalkExpr(&sWalker, pTerm->pExpr);
+        if( sWalker.eCode ) continue;
+      }
+    }else{
+      if( ExprHasProperty(pTerm->pExpr, EP_OuterON) ) continue;
+    }
+
+    /* All terms in pWLoop->aLTerm[] except pEndRange are used to initialize
+    ** the cursor.  These terms are not needed as hints for a pure range
+    ** scan (that has no == terms) so omit them. */
+    if( pLoop->u.btree.nEq==0 && pTerm!=pEndRange ){
+      for(j=0; j<pLoop->nLTerm && pLoop->aLTerm[j]!=pTerm; j++){}
+      if( j<pLoop->nLTerm ) continue;
+    }
+
+    /* No subqueries or non-deterministic functions allowed */
+    if( sqlite3ExprContainsSubquery(pTerm->pExpr) ) continue;
+
+    /* For an index scan, make sure referenced columns are actually in
+    ** the index. */
+    if( sHint.pIdx!=0 ){
+      sWalker.eCode = 0;
+      sWalker.xExprCallback = codeCursorHintCheckExpr;
+      sqlite3WalkExpr(&sWalker, pTerm->pExpr);
+      if( sWalker.eCode ) continue;
+    }
+
+    /* If we survive all prior tests, that means this term is worth hinting */
+    pExpr = sqlite3ExprAnd(pParse, pExpr, sqlite3ExprDup(db, pTerm->pExpr, 0));
+  }
+  if( pExpr!=0 ){
+    sWalker.xExprCallback = codeCursorHintFixExpr;
+    if( pParse->nErr==0 ) sqlite3WalkExpr(&sWalker, pExpr);
+    sqlite3VdbeAddOp4(v, OP_CursorHint,
+                      (sHint.pIdx ? sHint.iIdxCur : sHint.iTabCur), 0, 0,
+                      (const char*)pExpr, P4_EXPR);
+  }
+}
+#else
+# define codeCursorHint(A,B,C,D)  /* No-op */
+#endif /* SQLITE_ENABLE_CURSOR_HINTS */
+
+/*
+** Cursor iCur is open on an intkey b-tree (a table). Register iRowid contains
+** a rowid value just read from cursor iIdxCur, open on index pIdx. This
+** function generates code to do a deferred seek of cursor iCur to the
+** rowid stored in register iRowid.
+**
+** Normally, this is just:
+**
+**   OP_DeferredSeek $iCur $iRowid
+**
+** Which causes a seek on $iCur to the row with rowid $iRowid.
+**
+** However, if the scan currently being coded is a branch of an OR-loop and
+** the statement currently being coded is a SELECT, then additional information
+** is added that might allow OP_Column to omit the seek and instead do its
+** lookup on the index, thus avoiding an expensive seek operation.  To
+** enable this optimization, the P3 of OP_DeferredSeek is set to iIdxCur
+** and P4 is set to an array of integers containing one entry for each column
+** in the table.  For each table column, if the column is the i'th
+** column of the index, then the corresponding array entry is set to (i+1).
+** If the column does not appear in the index at all, the array entry is set
+** to 0.  The OP_Column opcode can check this array to see if the column it
+** wants is in the index and if it is, it will substitute the index cursor
+** and column number and continue with those new values, rather than seeking
+** the table cursor.
+*/
+static void codeDeferredSeek(
+  WhereInfo *pWInfo,              /* Where clause context */
+  Index *pIdx,                    /* Index scan is using */
+  int iCur,                       /* Cursor for IPK b-tree */
+  int iIdxCur                     /* Index cursor */
+){
+  Parse *pParse = pWInfo->pParse; /* Parse context */
+  Vdbe *v = pParse->pVdbe;        /* Vdbe to generate code within */
+
+  assert( iIdxCur>0 );
+  assert( pIdx->aiColumn[pIdx->nColumn-1]==-1 );
+ 
+  pWInfo->bDeferredSeek = 1;
+  sqlite3VdbeAddOp3(v, OP_DeferredSeek, iIdxCur, 0, iCur);
+  if( (pWInfo->wctrlFlags & (WHERE_OR_SUBCLAUSE|WHERE_RIGHT_JOIN))
+   && DbMaskAllZero(sqlite3ParseToplevel(pParse)->writeMask)
+  ){
+    int i;
+    Table *pTab = pIdx->pTable;
+    u32 *ai = (u32*)sqlite3DbMallocZero(pParse->db, sizeof(u32)*(pTab->nCol+1));
+    if( ai ){
+      ai[0] = pTab->nCol;
+      for(i=0; i<pIdx->nColumn-1; i++){
+        int x1, x2;
+        assert( pIdx->aiColumn[i]<pTab->nCol );
+        x1 = pIdx->aiColumn[i];
+        x2 = sqlite3TableColumnToStorage(pTab, x1);
+        testcase( x1!=x2 );
+        if( x1>=0 ) ai[x2+1] = i+1;
+      }
+      sqlite3VdbeChangeP4(v, -1, (char*)ai, P4_INTARRAY);
+    }
+  }
+}
+
+/*
+** If the expression passed as the second argument is a vector, generate
+** code to write the first nReg elements of the vector into an array
+** of registers starting with iReg.
+**
+** If the expression is not a vector, then nReg must be passed 1. In
+** this case, generate code to evaluate the expression and leave the
+** result in register iReg.
+*/
+static void codeExprOrVector(Parse *pParse, Expr *p, int iReg, int nReg){
+  assert( nReg>0 );
+  if( p && sqlite3ExprIsVector(p) ){
+#ifndef SQLITE_OMIT_SUBQUERY
+    if( ExprUseXSelect(p) ){
+      Vdbe *v = pParse->pVdbe;
+      int iSelect;
+      assert( p->op==TK_SELECT );
+      iSelect = sqlite3CodeSubselect(pParse, p);
+      sqlite3VdbeAddOp3(v, OP_Copy, iSelect, iReg, nReg-1);
+    }else
+#endif
+    {
+      int i;
+      const ExprList *pList;
+      assert( ExprUseXList(p) );
+      pList = p->x.pList;
+      assert( nReg<=pList->nExpr );
+      for(i=0; i<nReg; i++){
+        sqlite3ExprCode(pParse, pList->a[i].pExpr, iReg+i);
+      }
+    }
+  }else{
+    assert( nReg==1 || pParse->nErr );
+    sqlite3ExprCode(pParse, p, iReg);
+  }
+}
+
+/*
+** The pTruth expression is always true because it is the WHERE clause
+** a partial index that is driving a query loop.  Look through all of the
+** WHERE clause terms on the query, and if any of those terms must be
+** true because pTruth is true, then mark those WHERE clause terms as
+** coded.
+*/
+static void whereApplyPartialIndexConstraints(
+  Expr *pTruth,
+  int iTabCur,
+  WhereClause *pWC
+){
+  int i;
+  WhereTerm *pTerm;
+  while( pTruth->op==TK_AND ){
+    whereApplyPartialIndexConstraints(pTruth->pLeft, iTabCur, pWC);
+    pTruth = pTruth->pRight;
+  }
+  for(i=0, pTerm=pWC->a; i<pWC->nTerm; i++, pTerm++){
+    Expr *pExpr;
+    if( pTerm->wtFlags & TERM_CODED ) continue;
+    pExpr = pTerm->pExpr;
+    if( sqlite3ExprCompare(0, pExpr, pTruth, iTabCur)==0 ){
+      pTerm->wtFlags |= TERM_CODED;
+    }
+  }
+}
+
+/*
+** This routine is called right after An OP_Filter has been generated and
+** before the corresponding index search has been performed.  This routine
+** checks to see if there are additional Bloom filters in inner loops that
+** can be checked prior to doing the index lookup.  If there are available
+** inner-loop Bloom filters, then evaluate those filters now, before the
+** index lookup.  The idea is that a Bloom filter check is way faster than
+** an index lookup, and the Bloom filter might return false, meaning that
+** the index lookup can be skipped.
+**
+** We know that an inner loop uses a Bloom filter because it has the
+** WhereLevel.regFilter set.  If an inner-loop Bloom filter is checked,
+** then clear the WhereLevel.regFilter value to prevent the Bloom filter
+** from being checked a second time when the inner loop is evaluated.
+*/
+static SQLITE_NOINLINE void filterPullDown(
+  Parse *pParse,       /* Parsing context */
+  WhereInfo *pWInfo,   /* Complete information about the WHERE clause */
+  int iLevel,          /* Which level of pWInfo->a[] should be coded */
+  int addrNxt,         /* Jump here to bypass inner loops */
+  Bitmask notReady     /* Loops that are not ready */
+){
+  while( ++iLevel < pWInfo->nLevel ){
+    WhereLevel *pLevel = &pWInfo->a[iLevel];
+    WhereLoop *pLoop = pLevel->pWLoop;
+    if( pLevel->regFilter==0 ) continue;
+    if( pLevel->pWLoop->nSkip ) continue;
+    /*         ,--- Because sqlite3ConstructBloomFilter() has will not have set
+    **  vvvvv--'    pLevel->regFilter if this were true. */
+    if( NEVER(pLoop->prereq & notReady) ) continue;
+    assert( pLevel->addrBrk==0 );
+    pLevel->addrBrk = addrNxt;
+    if( pLoop->wsFlags & WHERE_IPK ){
+      WhereTerm *pTerm = pLoop->aLTerm[0];
+      int regRowid;
+      assert( pTerm!=0 );
+      assert( pTerm->pExpr!=0 );
+      testcase( pTerm->wtFlags & TERM_VIRTUAL );
+      regRowid = sqlite3GetTempReg(pParse);
+      regRowid = codeEqualityTerm(pParse, pTerm, pLevel, 0, 0, regRowid);
+      sqlite3VdbeAddOp2(pParse->pVdbe, OP_MustBeInt, regRowid, addrNxt);
+      VdbeCoverage(pParse->pVdbe);
+      sqlite3VdbeAddOp4Int(pParse->pVdbe, OP_Filter, pLevel->regFilter,
+                           addrNxt, regRowid, 1);
+      VdbeCoverage(pParse->pVdbe);
+    }else{
+      u16 nEq = pLoop->u.btree.nEq;
+      int r1;
+      char *zStartAff;
+
+      assert( pLoop->wsFlags & WHERE_INDEXED );
+      assert( (pLoop->wsFlags & WHERE_COLUMN_IN)==0 );
+      r1 = codeAllEqualityTerms(pParse,pLevel,0,0,&zStartAff);
+      codeApplyAffinity(pParse, r1, nEq, zStartAff);
+      sqlite3DbFree(pParse->db, zStartAff);
+      sqlite3VdbeAddOp4Int(pParse->pVdbe, OP_Filter, pLevel->regFilter,
+                           addrNxt, r1, nEq);
+      VdbeCoverage(pParse->pVdbe);
+    }
+    pLevel->regFilter = 0;
+    pLevel->addrBrk = 0;
+  }
+}
+
+/*
+** Generate code for the start of the iLevel-th loop in the WHERE clause
+** implementation described by pWInfo.
+*/
+Bitmask sqlite3WhereCodeOneLoopStart(
+  Parse *pParse,       /* Parsing context */
+  Vdbe *v,             /* Prepared statement under construction */
+  WhereInfo *pWInfo,   /* Complete information about the WHERE clause */
+  int iLevel,          /* Which level of pWInfo->a[] should be coded */
+  WhereLevel *pLevel,  /* The current level pointer */
+  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 bRev;            /* True if we need to scan in reverse order */
+  WhereLoop *pLoop;    /* The WhereLoop object being coded */
+  WhereClause *pWC;    /* Decomposition of the entire WHERE clause */
+  WhereTerm *pTerm;               /* A WHERE clause term */
+  sqlite3 *db;                    /* Database connection */
+  SrcItem *pTabItem;              /* FROM clause term being coded */
+  int addrBrk;                    /* Jump here to break out of the loop */
+  int addrHalt;                   /* addrBrk for the outermost 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 */
+  Index *pIdx = 0;          /* Index used by loop (if any) */
+  int iLoop;                /* Iteration of constraint generator loop */
+
+  pWC = &pWInfo->sWC;
+  db = pParse->db;
+  pLoop = pLevel->pWLoop;
+  pTabItem = &pWInfo->pTabList->a[pLevel->iFrom];
+  iCur = pTabItem->iCursor;
+  pLevel->notReady = notReady & ~sqlite3WhereGetMask(&pWInfo->sMaskSet, iCur);
+  bRev = (pWInfo->revMask>>iLevel)&1;
+  VdbeModuleComment((v, "Begin WHERE-loop%d: %s",iLevel,pTabItem->pTab->zName));
+#if WHERETRACE_ENABLED /* 0x4001 */
+  if( sqlite3WhereTrace & 0x1 ){
+    sqlite3DebugPrintf("Coding level %d of %d:  notReady=%llx  iFrom=%d\n",
+       iLevel, pWInfo->nLevel, (u64)notReady, pLevel->iFrom);
+    if( sqlite3WhereTrace & 0x1000 ){
+      sqlite3WhereLoopPrint(pLoop, pWC);
+    }
+  }
+  if( (sqlite3WhereTrace & 0x4001)==0x4001 ){
+    if( iLevel==0 ){
+      sqlite3DebugPrintf("WHERE clause being coded:\n");
+      sqlite3TreeViewExpr(0, pWInfo->pWhere, 0);
+    }
+    sqlite3DebugPrintf("All WHERE-clause terms before coding:\n");
+    sqlite3WhereClausePrint(pWC);
+  }
+#endif
+
+  /* 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(pParse);
+  addrCont = pLevel->addrCont = sqlite3VdbeMakeLabel(pParse);
+
+  /* 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.
+  */
+  assert( (pWInfo->wctrlFlags & (WHERE_OR_SUBCLAUSE|WHERE_RIGHT_JOIN))
+       || pLevel->iFrom>0 || (pTabItem[0].fg.jointype & JT_LEFT)==0
+  );
+  if( pLevel->iFrom>0 && (pTabItem[0].fg.jointype & JT_LEFT)!=0 ){
+    pLevel->iLeftJoin = ++pParse->nMem;
+    sqlite3VdbeAddOp2(v, OP_Integer, 0, pLevel->iLeftJoin);
+    VdbeComment((v, "init LEFT JOIN no-match flag"));
+  }
+
+  /* Compute a safe address to jump to if we discover that the table for
+  ** this loop is empty and can never contribute content. */
+  for(j=iLevel; j>0; j--){
+    if( pWInfo->a[j].iLeftJoin ) break;
+    if( pWInfo->a[j].pRJ ) break;
+  }
+  addrHalt = pWInfo->a[j].addrBrk;
+
+  /* Special case of a FROM clause subquery implemented as a co-routine */
+  if( pTabItem->fg.viaCoroutine ){
+    int regYield = pTabItem->regReturn;
+    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, pTabItem->addrFillSub);
+    pLevel->p2 =  sqlite3VdbeAddOp2(v, OP_Yield, regYield, addrBrk);
+    VdbeCoverage(v);
+    VdbeComment((v, "next row of %s", pTabItem->pTab->zName));
+    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;
+
+    iReg = sqlite3GetTempRange(pParse, nConstraint+2);
+    addrNotFound = pLevel->addrBrk;
+    for(j=0; j<nConstraint; j++){
+      int iTarget = iReg+j+2;
+      pTerm = pLoop->aLTerm[j];
+      if( NEVER(pTerm==0) ) continue;
+      if( pTerm->eOperator & WO_IN ){
+        if( SMASKBIT32(j) & pLoop->u.vtab.mHandleIn ){
+          int iTab = pParse->nTab++;
+          int iCache = ++pParse->nMem;
+          sqlite3CodeRhsOfIN(pParse, pTerm->pExpr, iTab);
+          sqlite3VdbeAddOp3(v, OP_VInitIn, iTab, iTarget, iCache);
+        }else{
+          codeEqualityTerm(pParse, pTerm, pLevel, j, bRev, iTarget);
+          addrNotFound = pLevel->addrNxt;
+        }
+      }else{
+        Expr *pRight = pTerm->pExpr->pRight;
+        codeExprOrVector(pParse, pRight, iTarget, 1);
+        if( pTerm->eMatchOp==SQLITE_INDEX_CONSTRAINT_OFFSET
+         && pLoop->u.vtab.bOmitOffset
+        ){
+          assert( pTerm->eOperator==WO_AUX );
+          assert( pWInfo->pSelect!=0 );
+          assert( pWInfo->pSelect->iOffset>0 );
+          sqlite3VdbeAddOp2(v, OP_Integer, 0, pWInfo->pSelect->iOffset);
+          VdbeComment((v,"Zero OFFSET counter"));
+        }
+      }
+    }
+    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_DYNAMIC : P4_STATIC);
+    VdbeCoverage(v);
+    pLoop->u.vtab.needFree = 0;
+    /* An OOM inside of AddOp4(OP_VFilter) instruction above might have freed
+    ** the u.vtab.idxStr.  NULL it out to prevent a use-after-free */
+    if( db->mallocFailed ) pLoop->u.vtab.idxStr = 0;
+    pLevel->p1 = iCur;
+    pLevel->op = pWInfo->eOnePass ? OP_Noop : OP_VNext;
+    pLevel->p2 = sqlite3VdbeCurrentAddr(v);
+    assert( (pLoop->wsFlags & WHERE_MULTI_OR)==0 );
+
+    for(j=0; j<nConstraint; j++){
+      pTerm = pLoop->aLTerm[j];
+      if( j<16 && (pLoop->u.vtab.omitMask>>j)&1 ){
+        disableTerm(pLevel, pTerm);
+        continue;
+      }
+      if( (pTerm->eOperator & WO_IN)!=0
+       && (SMASKBIT32(j) & pLoop->u.vtab.mHandleIn)==0
+       && !db->mallocFailed
+      ){
+        Expr *pCompare;  /* The comparison operator */
+        Expr *pRight;    /* RHS of the comparison */
+        VdbeOp *pOp;     /* Opcode to access the value of the IN constraint */
+        int iIn;         /* IN loop corresponding to the j-th constraint */
+
+        /* Reload the constraint value into reg[iReg+j+2].  The same value
+        ** was loaded into the same register prior to the OP_VFilter, but
+        ** the xFilter implementation might have changed the datatype or
+        ** encoding of the value in the register, so it *must* be reloaded.
+        */
+        for(iIn=0; ALWAYS(iIn<pLevel->u.in.nIn); iIn++){
+          pOp = sqlite3VdbeGetOp(v, pLevel->u.in.aInLoop[iIn].addrInTop);
+          if( (pOp->opcode==OP_Column && pOp->p3==iReg+j+2)
+           || (pOp->opcode==OP_Rowid && pOp->p2==iReg+j+2)
+          ){
+            testcase( pOp->opcode==OP_Rowid );
+            sqlite3VdbeAddOp3(v, pOp->opcode, pOp->p1, pOp->p2, pOp->p3);
+            break;
+          }
+        }
+
+        /* Generate code that will continue to the next row if
+        ** the IN constraint is not satisfied
+        */
+        pCompare = sqlite3PExpr(pParse, TK_EQ, 0, 0);
+        if( !db->mallocFailed ){
+          int iFld = pTerm->u.x.iField;
+          Expr *pLeft = pTerm->pExpr->pLeft;
+          assert( pLeft!=0 );
+          if( iFld>0 ){
+            assert( pLeft->op==TK_VECTOR );
+            assert( ExprUseXList(pLeft) );
+            assert( iFld<=pLeft->x.pList->nExpr );
+            pCompare->pLeft = pLeft->x.pList->a[iFld-1].pExpr;
+          }else{
+            pCompare->pLeft = pLeft;
+          }
+          pCompare->pRight = pRight = sqlite3Expr(db, TK_REGISTER, 0);
+          if( pRight ){
+            pRight->iTable = iReg+j+2;
+            sqlite3ExprIfFalse(
+                pParse, pCompare, pLevel->addrCont, SQLITE_JUMPIFNULL
+            );
+          }
+          pCompare->pLeft = 0;
+        }
+        sqlite3ExprDelete(db, pCompare);
+      }
+    }
+
+    /* These registers need to be preserved in case there is an IN operator
+    ** loop.  So we could deallocate the registers here (and potentially
+    ** reuse them later) if (pLoop->wsFlags & WHERE_IN_ABLE)==0.  But it seems
+    ** simpler and safer to simply not reuse the registers.
+    **
+    **    sqlite3ReleaseTempRange(pParse, iReg, nConstraint+2);
+    */
+  }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 );
+    pTerm = pLoop->aLTerm[0];
+    assert( pTerm!=0 );
+    assert( pTerm->pExpr!=0 );
+    testcase( pTerm->wtFlags & TERM_VIRTUAL );
+    iReleaseReg = ++pParse->nMem;
+    iRowidReg = codeEqualityTerm(pParse, pTerm, pLevel, 0, bRev, iReleaseReg);
+    if( iRowidReg!=iReleaseReg ) sqlite3ReleaseTempReg(pParse, iReleaseReg);
+    addrNxt = pLevel->addrNxt;
+    if( pLevel->regFilter ){
+      sqlite3VdbeAddOp2(v, OP_MustBeInt, iRowidReg, addrNxt);
+      VdbeCoverage(v);
+      sqlite3VdbeAddOp4Int(v, OP_Filter, pLevel->regFilter, addrNxt,
+                           iRowidReg, 1);
+      VdbeCoverage(v);
+      filterPullDown(pParse, pWInfo, iLevel, addrNxt, notReady);
+    }
+    sqlite3VdbeAddOp3(v, OP_SeekRowid, iCur, addrNxt, iRowidReg);
+    VdbeCoverage(v);
+    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;
+
+    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;
+    }
+    codeCursorHint(pTabItem, pWInfo, pLevel, pEnd);
+    if( pStart ){
+      Expr *pX;             /* The expression that defines the start bound */
+      int r1, rTemp;        /* Registers for holding the start boundary */
+      int op;               /* Cursor seek operation */
+
+      /* 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 correct. */
+
+      assert( (pStart->wtFlags & TERM_VNULL)==0 );
+      testcase( pStart->wtFlags & TERM_VIRTUAL );
+      pX = pStart->pExpr;
+      assert( pX!=0 );
+      testcase( pStart->leftCursor!=iCur ); /* transitive constraints */
+      if( sqlite3ExprIsVector(pX->pRight) ){
+        r1 = rTemp = sqlite3GetTempReg(pParse);
+        codeExprOrVector(pParse, pX->pRight, r1, 1);
+        testcase( pX->op==TK_GT );
+        testcase( pX->op==TK_GE );
+        testcase( pX->op==TK_LT );
+        testcase( pX->op==TK_LE );
+        op = aMoveOp[((pX->op - TK_GT - 1) & 0x3) | 0x1];
+        assert( pX->op!=TK_GT || op==OP_SeekGE );
+        assert( pX->op!=TK_GE || op==OP_SeekGE );
+        assert( pX->op!=TK_LT || op==OP_SeekLE );
+        assert( pX->op!=TK_LE || op==OP_SeekLE );
+      }else{
+        r1 = sqlite3ExprCodeTemp(pParse, pX->pRight, &rTemp);
+        disableTerm(pLevel, pStart);
+        op = aMoveOp[(pX->op - TK_GT)];
+      }
+      sqlite3VdbeAddOp3(v, op, iCur, addrBrk, r1);
+      VdbeComment((v, "pk"));
+      VdbeCoverageIf(v, pX->op==TK_GT);
+      VdbeCoverageIf(v, pX->op==TK_LE);
+      VdbeCoverageIf(v, pX->op==TK_LT);
+      VdbeCoverageIf(v, pX->op==TK_GE);
+      sqlite3ReleaseTempReg(pParse, rTemp);
+    }else{
+      sqlite3VdbeAddOp2(v, bRev ? OP_Last : OP_Rewind, iCur, addrHalt);
+      VdbeCoverageIf(v, bRev==0);
+      VdbeCoverageIf(v, bRev!=0);
+    }
+    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;
+      codeExprOrVector(pParse, pX->pRight, memEndValue, 1);
+      if( 0==sqlite3ExprIsVector(pX->pRight)
+       && (pX->op==TK_LT || pX->op==TK_GT)
+      ){
+        testOp = bRev ? OP_Le : OP_Ge;
+      }else{
+        testOp = bRev ? OP_Lt : OP_Gt;
+      }
+      if( 0==sqlite3ExprIsVector(pX->pRight) ){
+        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 = ++pParse->nMem;
+      sqlite3VdbeAddOp2(v, OP_Rowid, iCur, iRowidReg);
+      sqlite3VdbeAddOp3(v, testOp, memEndValue, addrBrk, iRowidReg);
+      VdbeCoverageIf(v, testOp==OP_Le);
+      VdbeCoverageIf(v, testOp==OP_Lt);
+      VdbeCoverageIf(v, testOp==OP_Ge);
+      VdbeCoverageIf(v, testOp==OP_Gt);
+      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_IdxGE,            /* 0: (end_constraints && !bRev && !endEq) */
+      OP_IdxGT,            /* 1: (end_constraints && !bRev &&  endEq) */
+      OP_IdxLE,            /* 2: (end_constraints &&  bRev && !endEq) */
+      OP_IdxLT,            /* 3: (end_constraints &&  bRev &&  endEq) */
+    };
+    u16 nEq = pLoop->u.btree.nEq;     /* Number of == or IN terms */
+    u16 nBtm = pLoop->u.btree.nBtm;   /* Length of BTM vector */
+    u16 nTop = pLoop->u.btree.nTop;   /* Length of TOP vector */
+    int regBase;                 /* Base register holding constraint values */
+    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 */
+    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 = 0;           /* Affinity for end of range constraint */
+    u8 bSeekPastNull = 0;        /* True to seek past initial nulls */
+    u8 bStopAtNull = 0;          /* Add condition to terminate at NULLs */
+    int omitTable;               /* True if we use the index only */
+    int regBignull = 0;          /* big-null flag register */
+    int addrSeekScan = 0;        /* Opcode of the OP_SeekScan, if any */
+
+    pIdx = pLoop->u.btree.pIndex;
+    iIdxCur = pLevel->iIdxCur;
+    assert( nEq>=pLoop->nSkip );
+
+    /* 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 = MAX(nExtraReg, pLoop->u.btree.nBtm);
+      /* Like optimization range constraints always occur in pairs */
+      assert( (pRangeStart->wtFlags & TERM_LIKEOPT)==0 ||
+              (pLoop->wsFlags & WHERE_TOP_LIMIT)!=0 );
+    }
+    if( pLoop->wsFlags & WHERE_TOP_LIMIT ){
+      pRangeEnd = pLoop->aLTerm[j++];
+      nExtraReg = MAX(nExtraReg, pLoop->u.btree.nTop);
+#ifndef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+      if( (pRangeEnd->wtFlags & TERM_LIKEOPT)!=0 ){
+        assert( pRangeStart!=0 );                     /* LIKE opt constraints */
+        assert( pRangeStart->wtFlags & TERM_LIKEOPT );   /* occur in pairs */
+        pLevel->iLikeRepCntr = (u32)++pParse->nMem;
+        sqlite3VdbeAddOp2(v, OP_Integer, 1, (int)pLevel->iLikeRepCntr);
+        VdbeComment((v, "LIKE loop counter"));
+        pLevel->addrLikeRep = sqlite3VdbeCurrentAddr(v);
+        /* iLikeRepCntr actually stores 2x the counter register number.  The
+        ** bottom bit indicates whether the search order is ASC or DESC. */
+        testcase( bRev );
+        testcase( pIdx->aSortOrder[nEq]==SQLITE_SO_DESC );
+        assert( (bRev & ~1)==0 );
+        pLevel->iLikeRepCntr <<=1;
+        pLevel->iLikeRepCntr |= bRev ^ (pIdx->aSortOrder[nEq]==SQLITE_SO_DESC);
+      }
+#endif
+      if( pRangeStart==0 ){
+        j = pIdx->aiColumn[nEq];
+        if( (j>=0 && pIdx->pTable->aCol[j].notNull==0) || j==XN_EXPR ){
+          bSeekPastNull = 1;
+        }
+      }
+    }
+    assert( pRangeEnd==0 || (pRangeEnd->wtFlags & TERM_VNULL)==0 );
+
+    /* If the WHERE_BIGNULL_SORT flag is set, then index column nEq uses
+    ** a non-default "big-null" sort (either ASC NULLS LAST or DESC NULLS
+    ** FIRST). In both cases separate ordered scans are made of those
+    ** index entries for which the column is null and for those for which
+    ** it is not. For an ASC sort, the non-NULL entries are scanned first.
+    ** For DESC, NULL entries are scanned first.
+    */
+    if( (pLoop->wsFlags & (WHERE_TOP_LIMIT|WHERE_BTM_LIMIT))==0
+     && (pLoop->wsFlags & WHERE_BIGNULL_SORT)!=0
+    ){
+      assert( bSeekPastNull==0 && nExtraReg==0 && nBtm==0 && nTop==0 );
+      assert( pRangeEnd==0 && pRangeStart==0 );
+      testcase( pLoop->nSkip>0 );
+      nExtraReg = 1;
+      bSeekPastNull = 1;
+      pLevel->regBignull = regBignull = ++pParse->nMem;
+      if( pLevel->iLeftJoin ){
+        sqlite3VdbeAddOp2(v, OP_Integer, 0, regBignull);
+      }
+      pLevel->addrBignull = sqlite3VdbeMakeLabel(pParse);
+    }
+
+    /* 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)) ){
+      SWAP(WhereTerm *, pRangeEnd, pRangeStart);
+      SWAP(u8, bSeekPastNull, bStopAtNull);
+      SWAP(u8, nBtm, nTop);
+    }
+
+    if( iLevel>0 && (pLoop->wsFlags & WHERE_IN_SEEKSCAN)!=0 ){
+      /* In case OP_SeekScan is used, ensure that the index cursor does not
+      ** point to a valid row for the first iteration of this loop. */
+      sqlite3VdbeAddOp1(v, OP_NullRow, iIdxCur);
+    }
+
+    /* 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.
+    */
+    codeCursorHint(pTabItem, pWInfo, pLevel, pRangeEnd);
+    regBase = codeAllEqualityTerms(pParse,pLevel,bRev,nExtraReg,&zStartAff);
+    assert( zStartAff==0 || sqlite3Strlen30(zStartAff)>=nEq );
+    if( zStartAff && nTop ){
+      zEndAff = sqlite3DbStrDup(db, &zStartAff[nEq]);
+    }
+    addrNxt = (regBignull ? pLevel->addrBignull : pLevel->addrNxt);
+
+    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;
+      codeExprOrVector(pParse, pRight, regBase+nEq, nBtm);
+      whereLikeOptimizationStringFixup(v, pLevel, pRangeStart);
+      if( (pRangeStart->wtFlags & TERM_VNULL)==0
+       && sqlite3ExprCanBeNull(pRight)
+      ){
+        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
+        VdbeCoverage(v);
+      }
+      if( zStartAff ){
+        updateRangeAffinityStr(pRight, nBtm, &zStartAff[nEq]);
+      } 
+      nConstraint += nBtm;
+      testcase( pRangeStart->wtFlags & TERM_VIRTUAL );
+      if( sqlite3ExprIsVector(pRight)==0 ){
+        disableTerm(pLevel, pRangeStart);
+      }else{
+        startEq = 1;
+      }
+      bSeekPastNull = 0;
+    }else if( bSeekPastNull ){
+      startEq = 0;
+      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
+      start_constraints = 1;
+      nConstraint++;
+    }else if( regBignull ){
+      sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
+      start_constraints = 1;
+      nConstraint++;
+    }
+    codeApplyAffinity(pParse, regBase, nConstraint - bSeekPastNull, zStartAff);
+    if( pLoop->nSkip>0 && nConstraint==pLoop->nSkip ){
+      /* The skip-scan logic inside the call to codeAllEqualityConstraints()
+      ** above has already left the cursor sitting on the correct row,
+      ** so no further seeking is needed */
+    }else{
+      if( regBignull ){
+        sqlite3VdbeAddOp2(v, OP_Integer, 1, regBignull);
+        VdbeComment((v, "NULL-scan pass ctr"));
+      }
+      if( pLevel->regFilter ){
+        sqlite3VdbeAddOp4Int(v, OP_Filter, pLevel->regFilter, addrNxt,
+                             regBase, nEq);
+        VdbeCoverage(v);
+        filterPullDown(pParse, pWInfo, iLevel, addrNxt, notReady);
+      }
+
+      op = aStartOp[(start_constraints<<2) + (startEq<<1) + bRev];
+      assert( op!=0 );
+      if( (pLoop->wsFlags & WHERE_IN_SEEKSCAN)!=0 && op==OP_SeekGE ){
+        assert( regBignull==0 );
+        /* TUNING:  The OP_SeekScan opcode seeks to reduce the number
+        ** of expensive seek operations by replacing a single seek with
+        ** 1 or more step operations.  The question is, how many steps
+        ** should we try before giving up and going with a seek.  The cost
+        ** of a seek is proportional to the logarithm of the of the number
+        ** of entries in the tree, so basing the number of steps to try
+        ** on the estimated number of rows in the btree seems like a good
+        ** guess. */
+        addrSeekScan = sqlite3VdbeAddOp1(v, OP_SeekScan,
+                                         (pIdx->aiRowLogEst[0]+9)/10);
+        if( pRangeStart || pRangeEnd ){
+          sqlite3VdbeChangeP5(v, 1);
+          sqlite3VdbeChangeP2(v, addrSeekScan, sqlite3VdbeCurrentAddr(v)+1);
+          addrSeekScan = 0;
+        }
+        VdbeCoverage(v);
+      }
+      sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
+      VdbeCoverage(v);
+      VdbeCoverageIf(v, op==OP_Rewind);  testcase( op==OP_Rewind );
+      VdbeCoverageIf(v, op==OP_Last);    testcase( op==OP_Last );
+      VdbeCoverageIf(v, op==OP_SeekGT);  testcase( op==OP_SeekGT );
+      VdbeCoverageIf(v, op==OP_SeekGE);  testcase( op==OP_SeekGE );
+      VdbeCoverageIf(v, op==OP_SeekLE);  testcase( op==OP_SeekLE );
+      VdbeCoverageIf(v, op==OP_SeekLT);  testcase( op==OP_SeekLT );
+
+      assert( bSeekPastNull==0 || bStopAtNull==0 );
+      if( regBignull ){
+        assert( bSeekPastNull==1 || bStopAtNull==1 );
+        assert( bSeekPastNull==!bStopAtNull );
+        assert( bStopAtNull==startEq );
+        sqlite3VdbeAddOp2(v, OP_Goto, 0, sqlite3VdbeCurrentAddr(v)+2);
+        op = aStartOp[(nConstraint>1)*4 + 2 + bRev];
+        sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase,
+                             nConstraint-startEq);
+        VdbeCoverage(v);
+        VdbeCoverageIf(v, op==OP_Rewind);  testcase( op==OP_Rewind );
+        VdbeCoverageIf(v, op==OP_Last);    testcase( op==OP_Last );
+        VdbeCoverageIf(v, op==OP_SeekGE);  testcase( op==OP_SeekGE );
+        VdbeCoverageIf(v, op==OP_SeekLE);  testcase( op==OP_SeekLE );
+        assert( op==OP_Rewind || op==OP_Last || op==OP_SeekGE || op==OP_SeekLE);
+      }
+    }
+
+    /* Load the value for the inequality constraint at the end of the
+    ** range (if any).
+    */
+    nConstraint = nEq;
+    assert( pLevel->p2==0 );
+    if( pRangeEnd ){
+      Expr *pRight = pRangeEnd->pExpr->pRight;
+      assert( addrSeekScan==0 );
+      codeExprOrVector(pParse, pRight, regBase+nEq, nTop);
+      whereLikeOptimizationStringFixup(v, pLevel, pRangeEnd);
+      if( (pRangeEnd->wtFlags & TERM_VNULL)==0
+       && sqlite3ExprCanBeNull(pRight)
+      ){
+        sqlite3VdbeAddOp2(v, OP_IsNull, regBase+nEq, addrNxt);
+        VdbeCoverage(v);
+      }
+      if( zEndAff ){
+        updateRangeAffinityStr(pRight, nTop, zEndAff);
+        codeApplyAffinity(pParse, regBase+nEq, nTop, zEndAff);
+      }else{
+        assert( pParse->db->mallocFailed );
+      }
+      nConstraint += nTop;
+      testcase( pRangeEnd->wtFlags & TERM_VIRTUAL );
+
+      if( sqlite3ExprIsVector(pRight)==0 ){
+        disableTerm(pLevel, pRangeEnd);
+      }else{
+        endEq = 1;
+      }
+    }else if( bStopAtNull ){
+      if( regBignull==0 ){
+        sqlite3VdbeAddOp2(v, OP_Null, 0, regBase+nEq);
+        endEq = 0;
+      }
+      nConstraint++;
+    }
+    if( zStartAff ) sqlite3DbNNFreeNN(db, zStartAff);
+    if( zEndAff ) sqlite3DbNNFreeNN(db, zEndAff);
+
+    /* Top of the loop body */
+    pLevel->p2 = sqlite3VdbeCurrentAddr(v);
+
+    /* Check if the index cursor is past the end of the range. */
+    if( nConstraint ){
+      if( regBignull ){
+        /* Except, skip the end-of-range check while doing the NULL-scan */
+        sqlite3VdbeAddOp2(v, OP_IfNot, regBignull, sqlite3VdbeCurrentAddr(v)+3);
+        VdbeComment((v, "If NULL-scan 2nd pass"));
+        VdbeCoverage(v);
+      }
+      op = aEndOp[bRev*2 + endEq];
+      sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase, nConstraint);
+      testcase( op==OP_IdxGT );  VdbeCoverageIf(v, op==OP_IdxGT );
+      testcase( op==OP_IdxGE );  VdbeCoverageIf(v, op==OP_IdxGE );
+      testcase( op==OP_IdxLT );  VdbeCoverageIf(v, op==OP_IdxLT );
+      testcase( op==OP_IdxLE );  VdbeCoverageIf(v, op==OP_IdxLE );
+      if( addrSeekScan ) sqlite3VdbeJumpHere(v, addrSeekScan);
+    }
+    if( regBignull ){
+      /* During a NULL-scan, check to see if we have reached the end of
+      ** the NULLs */
+      assert( bSeekPastNull==!bStopAtNull );
+      assert( bSeekPastNull+bStopAtNull==1 );
+      assert( nConstraint+bSeekPastNull>0 );
+      sqlite3VdbeAddOp2(v, OP_If, regBignull, sqlite3VdbeCurrentAddr(v)+2);
+      VdbeComment((v, "If NULL-scan 1st pass"));
+      VdbeCoverage(v);
+      op = aEndOp[bRev*2 + bSeekPastNull];
+      sqlite3VdbeAddOp4Int(v, op, iIdxCur, addrNxt, regBase,
+                           nConstraint+bSeekPastNull);
+      testcase( op==OP_IdxGT );  VdbeCoverageIf(v, op==OP_IdxGT );
+      testcase( op==OP_IdxGE );  VdbeCoverageIf(v, op==OP_IdxGE );
+      testcase( op==OP_IdxLT );  VdbeCoverageIf(v, op==OP_IdxLT );
+      testcase( op==OP_IdxLE );  VdbeCoverageIf(v, op==OP_IdxLE );
+    }
+
+    if( (pLoop->wsFlags & WHERE_IN_EARLYOUT)!=0 ){
+      sqlite3VdbeAddOp3(v, OP_SeekHit, iIdxCur, nEq, nEq);
+    }
+
+    /* Seek the table cursor, if required */
+    omitTable = (pLoop->wsFlags & WHERE_IDX_ONLY)!=0
+           && (pWInfo->wctrlFlags & (WHERE_OR_SUBCLAUSE|WHERE_RIGHT_JOIN))==0;
+    if( omitTable ){
+      /* pIdx is a covering index.  No need to access the main table. */
+    }else if( HasRowid(pIdx->pTable) ){
+      codeDeferredSeek(pWInfo, pIdx, iCur, iIdxCur);
+    }else if( iCur!=iIdxCur ){
+      Index *pPk = sqlite3PrimaryKeyIndex(pIdx->pTable);
+      iRowidReg = sqlite3GetTempRange(pParse, pPk->nKeyCol);
+      for(j=0; j<pPk->nKeyCol; j++){
+        k = sqlite3TableColumnToIndex(pIdx, pPk->aiColumn[j]);
+        sqlite3VdbeAddOp3(v, OP_Column, iIdxCur, k, iRowidReg+j);
+      }
+      sqlite3VdbeAddOp4Int(v, OP_NotFound, iCur, addrCont,
+                           iRowidReg, pPk->nKeyCol); VdbeCoverage(v);
+    }
+
+    if( pLevel->iLeftJoin==0 ){
+      /* If a partial index is driving the loop, try to eliminate WHERE clause
+      ** terms from the query that must be true due to the WHERE clause of
+      ** the partial index.
+      **
+      ** 2019-11-02 ticket 623eff57e76d45f6: This optimization does not work
+      ** for a LEFT JOIN.
+      */
+      if( pIdx->pPartIdxWhere ){
+        whereApplyPartialIndexConstraints(pIdx->pPartIdxWhere, iCur, pWC);
+      }
+    }else{
+      testcase( pIdx->pPartIdxWhere );
+      /* The following assert() is not a requirement, merely an observation:
+      ** The OR-optimization doesn't work for the right hand table of
+      ** a LEFT JOIN: */
+      assert( (pWInfo->wctrlFlags & (WHERE_OR_SUBCLAUSE|WHERE_RIGHT_JOIN))==0 );
+    }
+ 
+    /* Record the instruction used to terminate the loop. */
+    if( pLoop->wsFlags & WHERE_ONEROW ){
+      pLevel->op = OP_Noop;
+    }else if( bRev ){
+      pLevel->op = OP_Prev;
+    }else{
+      pLevel->op = OP_Next;
+    }
+    pLevel->p1 = iIdxCur;
+    pLevel->p3 = (pLoop->wsFlags&WHERE_UNQ_WANTED)!=0 ? 1:0;
+    if( (pLoop->wsFlags & WHERE_CONSTRAINT)==0 ){
+      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
+    }else{
+      assert( pLevel->p5==0 );
+    }
+    if( omitTable ) pIdx = 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>
+    **
+    ** Added 2014-05-26: If the table is a WITHOUT ROWID table, then
+    ** use an ephemeral index instead of a RowSet to record the primary
+    ** keys of the rows we have already seen.
+    **
+    */
+    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(pParse);/* 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 */
+    Table *pTab = pTabItem->pTab;
+
+    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 */
+      SrcItem *origSrc;              /* Original list of tables */
+      nNotReady = pWInfo->nLevel - iLevel - 1;
+      pOrTab = sqlite3DbMallocRawNN(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.  Or, create an ephemeral index
+    ** capable of holding primary keys in the case of a WITHOUT ROWID.
+    **
+    ** 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 ){
+      if( HasRowid(pTab) ){
+        regRowset = ++pParse->nMem;
+        sqlite3VdbeAddOp2(v, OP_Null, 0, regRowset);
+      }else{
+        Index *pPk = sqlite3PrimaryKeyIndex(pTab);
+        regRowset = pParse->nTab++;
+        sqlite3VdbeAddOp2(v, OP_OpenEphemeral, regRowset, pPk->nKeyCol);
+        sqlite3VdbeSetP4KeyInfo(pParse, pPk);
+      }
+      regRowid = ++pParse->nMem;
+    }
+    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 y
+    ** 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
+    **
+    ** 2022-02-04:  Do not push down slices of a row-value comparison.
+    ** In other words, "w" or "y" may not be a slice of a vector.  Otherwise,
+    ** the initialization of the right-hand operand of the vector comparison
+    ** might not occur, or might occur only in an OR branch that is not
+    ** taken.  dbsqlfuzz 80a9fade844b4fb43564efc972bcb2c68270f5d1.
+    **
+    ** 2022-03-03:  Do not push down expressions that involve subqueries.
+    ** The subquery might get coded as a subroutine.  Any table-references
+    ** in the subquery might be resolved to index-references for the index on
+    ** the OR branch in which the subroutine is coded.  But if the subroutine
+    ** is invoked from a different OR branch that uses a different index, such
+    ** index-references will not work.  tag-20220303a
+    ** https://sqlite.org/forum/forumpost/36937b197273d403
+    */
+    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;
+        testcase( pWC->a[iTerm].wtFlags & TERM_VIRTUAL );
+        testcase( pWC->a[iTerm].wtFlags & TERM_CODED );
+        testcase( pWC->a[iTerm].wtFlags & TERM_SLICE );
+        if( (pWC->a[iTerm].wtFlags & (TERM_VIRTUAL|TERM_CODED|TERM_SLICE))!=0 ){
+          continue;
+        }
+        if( (pWC->a[iTerm].eOperator & WO_ALL)==0 ) continue;
+        if( ExprHasProperty(pExpr, EP_Subquery) ) continue;  /* tag-20220303a */
+        pExpr = sqlite3ExprDup(db, pExpr, 0);
+        pAndExpr = sqlite3ExprAnd(pParse, pAndExpr, pExpr);
+      }
+      if( pAndExpr ){
+        /* The extra 0x10000 bit on the opcode is masked off and does not
+        ** become part of the new Expr.op.  However, it does make the
+        ** op==TK_AND comparison inside of sqlite3PExpr() false, and this
+        ** prevents sqlite3PExpr() from applying the AND short-circuit
+        ** optimization, which we do not want here. */
+        pAndExpr = sqlite3PExpr(pParse, TK_AND|0x10000, 0, pAndExpr);
+      }
+    }
+
+    /* Run a separate WHERE clause for each term of the OR clause.  After
+    ** eliminating duplicates from other WHERE clauses, the action for each
+    ** sub-WHERE clause is to to invoke the main loop body as a subroutine.
+    */
+    ExplainQueryPlan((pParse, 1, "MULTI-INDEX OR"));
+    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; /* Current OR clause term */
+        Expr *pDelete;                  /* Local copy of OR clause term */
+        int jmp1 = 0;                   /* Address of jump operation */
+        testcase( (pTabItem[0].fg.jointype & JT_LEFT)!=0
+               && !ExprHasProperty(pOrExpr, EP_OuterON)
+        ); /* See TH3 vtab25.400 and ticket 614b25314c766238 */
+        pDelete = pOrExpr = sqlite3ExprDup(db, pOrExpr, 0);
+        if( db->mallocFailed ){
+          sqlite3ExprDelete(db, pDelete);
+          continue;
+        }
+        if( pAndExpr ){
+          pAndExpr->pLeft = pOrExpr;
+          pOrExpr = pAndExpr;
+        }
+        /* Loop through table entries that match term pOrTerm. */
+        ExplainQueryPlan((pParse, 1, "INDEX %d", ii+1));
+        WHERETRACE(0xffffffff, ("Subplan for OR-clause:\n"));
+        pSubWInfo = sqlite3WhereBegin(pParse, pOrTab, pOrExpr, 0, 0, 0,
+                                      WHERE_OR_SUBCLAUSE, iCovCur);
+        assert( pSubWInfo || pParse->nErr );
+        if( pSubWInfo ){
+          WhereLoop *pSubLoop;
+          int addrExplain = sqlite3WhereExplainOneScan(
+              pParse, pOrTab, &pSubWInfo->a[0], 0
+          );
+          sqlite3WhereAddScanStatus(v, pOrTab, &pSubWInfo->a[0], addrExplain);
+
+          /* This is the sub-WHERE clause body.  First skip over
+          ** duplicate rows from prior sub-WHERE clauses, and record the
+          ** rowid (or PRIMARY KEY) for the current row so that the same
+          ** row will be skipped in subsequent sub-WHERE clauses.
+          */
+          if( (pWInfo->wctrlFlags & WHERE_DUPLICATES_OK)==0 ){
+            int iSet = ((ii==pOrWc->nTerm-1)?-1:ii);
+            if( HasRowid(pTab) ){
+              sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, -1, regRowid);
+              jmp1 = sqlite3VdbeAddOp4Int(v, OP_RowSetTest, regRowset, 0,
+                                          regRowid, iSet);
+              VdbeCoverage(v);
+            }else{
+              Index *pPk = sqlite3PrimaryKeyIndex(pTab);
+              int nPk = pPk->nKeyCol;
+              int iPk;
+              int r;
+
+              /* Read the PK into an array of temp registers. */
+              r = sqlite3GetTempRange(pParse, nPk);
+              for(iPk=0; iPk<nPk; iPk++){
+                int iCol = pPk->aiColumn[iPk];
+                sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, iCol,r+iPk);
+              }
+
+              /* Check if the temp table already contains this key. If so,
+              ** the row has already been included in the result set and
+              ** can be ignored (by jumping past the Gosub below). Otherwise,
+              ** insert the key into the temp table and proceed with processing
+              ** the row.
+              **
+              ** Use some of the same optimizations as OP_RowSetTest: If iSet
+              ** is zero, assume that the key cannot already be present in
+              ** the temp table. And if iSet is -1, assume that there is no
+              ** need to insert the key into the temp table, as it will never
+              ** be tested for.  */
+              if( iSet ){
+                jmp1 = sqlite3VdbeAddOp4Int(v, OP_Found, regRowset, 0, r, nPk);
+                VdbeCoverage(v);
+              }
+              if( iSet>=0 ){
+                sqlite3VdbeAddOp3(v, OP_MakeRecord, r, nPk, regRowid);
+                sqlite3VdbeAddOp4Int(v, OP_IdxInsert, regRowset, regRowid,
+                                     r, nPk);
+                if( iSet ) sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
+              }
+
+              /* Release the array of temp registers */
+              sqlite3ReleaseTempRange(pParse, r, nPk);
+            }
+          }
+
+          /* Invoke the main loop body as a subroutine */
+          sqlite3VdbeAddOp2(v, OP_Gosub, regReturn, iLoopBody);
+
+          /* Jump here (skipping the main loop body subroutine) if the
+          ** current sub-WHERE row is a duplicate from prior sub-WHEREs. */
+          if( jmp1 ) sqlite3VdbeJumpHere(v, jmp1);
+
+          /* 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)
+           && (HasRowid(pTab) || !IsPrimaryKeyIndex(pSubLoop->u.btree.pIndex))
+          ){
+            assert( pSubWInfo->a[0].iIdxCur==iCovCur );
+            pCov = pSubLoop->u.btree.pIndex;
+          }else{
+            pCov = 0;
+          }
+          if( sqlite3WhereUsesDeferredSeek(pSubWInfo) ){
+            pWInfo->bDeferredSeek = 1;
+          }
+
+          /* Finish the loop through table entries that match term pOrTerm. */
+          sqlite3WhereEnd(pSubWInfo);
+          ExplainQueryPlanPop(pParse);
+        }
+        sqlite3ExprDelete(db, pDelete);
+      }
+    }
+    ExplainQueryPlanPop(pParse);
+    assert( pLevel->pWLoop==pLoop );
+    assert( (pLoop->wsFlags & WHERE_MULTI_OR)!=0 );
+    assert( (pLoop->wsFlags & WHERE_IN_ABLE)==0 );
+    pLevel->u.pCoveringIdx = pCov;
+    if( pCov ) pLevel->iIdxCur = iCovCur;
+    if( pAndExpr ){
+      pAndExpr->pLeft = 0;
+      sqlite3ExprDelete(db, pAndExpr);
+    }
+    sqlite3VdbeChangeP1(v, iRetInit, sqlite3VdbeCurrentAddr(v));
+    sqlite3VdbeGoto(v, pLevel->addrBrk);
+    sqlite3VdbeResolveLabel(v, iLoopBody);
+
+    /* Set the P2 operand of the OP_Return opcode that will end the current
+    ** loop to point to this spot, which is the top of the next containing
+    ** loop.  The byte-code formatter will use that P2 value as a hint to
+    ** indent everything in between the this point and the final OP_Return.
+    ** See tag-20220407a in vdbe.c and shell.c */
+    assert( pLevel->op==OP_Return );
+    pLevel->p2 = sqlite3VdbeCurrentAddr(v);
+
+    if( pWInfo->nLevel>1 ){ sqlite3DbFreeNN(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 );
+    if( pTabItem->fg.isRecursive ){
+      /* Tables marked isRecursive have only a single row that is stored in
+      ** a pseudo-cursor.  No need to Rewind or Next such cursors. */
+      pLevel->op = OP_Noop;
+    }else{
+      codeCursorHint(pTabItem, pWInfo, pLevel, 0);
+      pLevel->op = aStep[bRev];
+      pLevel->p1 = iCur;
+      pLevel->p2 = 1 + sqlite3VdbeAddOp2(v, aStart[bRev], iCur, addrHalt);
+      VdbeCoverageIf(v, bRev==0);
+      VdbeCoverageIf(v, bRev!=0);
+      pLevel->p5 = SQLITE_STMTSTATUS_FULLSCAN_STEP;
+    }
+  }
+
+#ifdef SQLITE_ENABLE_STMT_SCANSTATUS
+  pLevel->addrVisit = sqlite3VdbeCurrentAddr(v);
+#endif
+
+  /* Insert code to test every subexpression that can be completely
+  ** computed using the current set of tables.
+  **
+  ** This loop may run between one and three times, depending on the
+  ** constraints to be generated. The value of stack variable iLoop
+  ** determines the constraints coded by each iteration, as follows:
+  **
+  ** iLoop==1: Code only expressions that are entirely covered by pIdx.
+  ** iLoop==2: Code remaining expressions that do not contain correlated
+  **           sub-queries. 
+  ** iLoop==3: Code all remaining expressions.
+  **
+  ** An effort is made to skip unnecessary iterations of the loop.
+  */
+  iLoop = (pIdx ? 1 : 2);
+  do{
+    int iNext = 0;                /* Next value for iLoop */
+    for(pTerm=pWC->a, j=pWC->nTerm; j>0; j--, pTerm++){
+      Expr *pE;
+      int skipLikeAddr = 0;
+      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_OR_SUBCLAUSE)!=0 );
+        pWInfo->untestedTerms = 1;
+        continue;
+      }
+      pE = pTerm->pExpr;
+      assert( pE!=0 );
+      if( pTabItem->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT) ){
+        if( !ExprHasProperty(pE,EP_OuterON|EP_InnerON) ){
+          /* Defer processing WHERE clause constraints until after outer
+          ** join processing.  tag-20220513a */
+          continue;
+        }else if( (pTabItem->fg.jointype & JT_LEFT)==JT_LEFT
+               && !ExprHasProperty(pE,EP_OuterON) ){
+          continue;
+        }else{
+          Bitmask m = sqlite3WhereGetMask(&pWInfo->sMaskSet, pE->w.iJoin);
+          if( m & pLevel->notReady ){
+            /* An ON clause that is not ripe */
+            continue;
+          }
+        }
+      }
+      if( iLoop==1 && !sqlite3ExprCoveredByIndex(pE, pLevel->iTabCur, pIdx) ){
+        iNext = 2;
+        continue;
+      }
+      if( iLoop<3 && (pTerm->wtFlags & TERM_VARSELECT) ){
+        if( iNext==0 ) iNext = 3;
+        continue;
+      }
+
+      if( (pTerm->wtFlags & TERM_LIKECOND)!=0 ){
+        /* If the TERM_LIKECOND flag is set, that means that the range search
+        ** is sufficient to guarantee that the LIKE operator is true, so we
+        ** can skip the call to the like(A,B) function.  But this only works
+        ** for strings.  So do not skip the call to the function on the pass
+        ** that compares BLOBs. */
+#ifdef SQLITE_LIKE_DOESNT_MATCH_BLOBS
+        continue;
+#else
+        u32 x = pLevel->iLikeRepCntr;
+        if( x>0 ){
+          skipLikeAddr = sqlite3VdbeAddOp1(v, (x&1)?OP_IfNot:OP_If,(int)(x>>1));
+          VdbeCoverageIf(v, (x&1)==1);
+          VdbeCoverageIf(v, (x&1)==0);
+        }
+#endif
+      }
+#ifdef WHERETRACE_ENABLED /* 0xffffffff */
+      if( sqlite3WhereTrace ){
+        VdbeNoopComment((v, "WhereTerm[%d] (%p) priority=%d",
+                         pWC->nTerm-j, pTerm, iLoop));
+      }
+      if( sqlite3WhereTrace & 0x4000 ){
+        sqlite3DebugPrintf("Coding auxiliary constraint:\n");
+        sqlite3WhereTermPrint(pTerm, pWC->nTerm-j);
+      }
+#endif
+      sqlite3ExprIfFalse(pParse, pE, addrCont, SQLITE_JUMPIFNULL);
+      if( skipLikeAddr ) sqlite3VdbeJumpHere(v, skipLikeAddr);
+      pTerm->wtFlags |= TERM_CODED;
+    }
+    iLoop = iNext;
+  }while( iLoop>0 );
+
+  /* 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->nBase; j>0; j--, pTerm++){
+    Expr *pE, sEAlt;
+    WhereTerm *pAlt;
+    if( pTerm->wtFlags & (TERM_VIRTUAL|TERM_CODED) ) continue;
+    if( (pTerm->eOperator & (WO_EQ|WO_IS))==0 ) continue;
+    if( (pTerm->eOperator & WO_EQUIV)==0 ) continue;
+    if( pTerm->leftCursor!=iCur ) continue;
+    if( pTabItem->fg.jointype & (JT_LEFT|JT_LTORJ|JT_RIGHT) ) continue;
+    pE = pTerm->pExpr;
+#ifdef WHERETRACE_ENABLED /* 0x4001 */
+    if( (sqlite3WhereTrace & 0x4001)==0x4001 ){
+      sqlite3DebugPrintf("Coding transitive constraint:\n");
+      sqlite3WhereTermPrint(pTerm, pWC->nTerm-j);
+    }
+#endif
+    assert( !ExprHasProperty(pE, EP_OuterON) );
+    assert( (pTerm->prereqRight & pLevel->notReady)!=0 );
+    assert( (pTerm->eOperator & (WO_OR|WO_AND))==0 );
+    pAlt = sqlite3WhereFindTerm(pWC, iCur, pTerm->u.x.leftColumn, notReady,
+                    WO_EQ|WO_IN|WO_IS, 0);
+    if( pAlt==0 ) continue;
+    if( pAlt->wtFlags & (TERM_CODED) ) continue;
+    if( (pAlt->eOperator & WO_IN)
+     && ExprUseXSelect(pAlt->pExpr)
+     && (pAlt->pExpr->x.pSelect->pEList->nExpr>1)
+    ){
+      continue;
+    }
+    testcase( pAlt->eOperator & WO_EQ );
+    testcase( pAlt->eOperator & WO_IS );
+    testcase( pAlt->eOperator & WO_IN );
+    VdbeModuleComment((v, "begin transitive constraint"));
+    sEAlt = *pAlt->pExpr;
+    sEAlt.pLeft = pE->pLeft;
+    sqlite3ExprIfFalse(pParse, &sEAlt, addrCont, SQLITE_JUMPIFNULL);
+    pAlt->wtFlags |= TERM_CODED;
+  }
+
+  /* For a RIGHT OUTER JOIN, record the fact that the current row has
+  ** been matched at least once.
+  */
+  if( pLevel->pRJ ){
+    Table *pTab;
+    int nPk;
+    int r;
+    int jmp1 = 0;
+    WhereRightJoin *pRJ = pLevel->pRJ;
+
+    /* pTab is the right-hand table of the RIGHT JOIN.  Generate code that
+    ** will record that the current row of that table has been matched at
+    ** least once.  This is accomplished by storing the PK for the row in
+    ** both the iMatch index and the regBloom Bloom filter.
+    */
+    pTab = pWInfo->pTabList->a[pLevel->iFrom].pTab;
+    if( HasRowid(pTab) ){
+      r = sqlite3GetTempRange(pParse, 2);
+      sqlite3ExprCodeGetColumnOfTable(v, pTab, pLevel->iTabCur, -1, r+1);
+      nPk = 1;
+    }else{
+      int iPk;
+      Index *pPk = sqlite3PrimaryKeyIndex(pTab);
+      nPk = pPk->nKeyCol;
+      r = sqlite3GetTempRange(pParse, nPk+1);
+      for(iPk=0; iPk<nPk; iPk++){
+        int iCol = pPk->aiColumn[iPk];
+        sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, iCol,r+1+iPk);
+      }
+    }
+    jmp1 = sqlite3VdbeAddOp4Int(v, OP_Found, pRJ->iMatch, 0, r+1, nPk);
+    VdbeCoverage(v);
+    VdbeComment((v, "match against %s", pTab->zName));
+    sqlite3VdbeAddOp3(v, OP_MakeRecord, r+1, nPk, r);
+    sqlite3VdbeAddOp4Int(v, OP_IdxInsert, pRJ->iMatch, r, r+1, nPk);
+    sqlite3VdbeAddOp4Int(v, OP_FilterAdd, pRJ->regBloom, 0, r+1, nPk);
+    sqlite3VdbeChangeP5(v, OPFLAG_USESEEKRESULT);
+    sqlite3VdbeJumpHere(v, jmp1);
+    sqlite3ReleaseTempRange(pParse, r, nPk+1);
+  }
+
+  /* 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"));
+    if( pLevel->pRJ==0 ){
+      goto code_outer_join_constraints; /* WHERE clause constraints */
+    }
+  }
+
+  if( pLevel->pRJ ){
+    /* Create a subroutine used to process all interior loops and code
+    ** of the RIGHT JOIN.  During normal operation, the subroutine will
+    ** be in-line with the rest of the code.  But at the end, a separate
+    ** loop will run that invokes this subroutine for unmatched rows
+    ** of pTab, with all tables to left begin set to NULL.
+    */
+    WhereRightJoin *pRJ = pLevel->pRJ;
+    sqlite3VdbeAddOp2(v, OP_BeginSubrtn, 0, pRJ->regReturn);
+    pRJ->addrSubrtn = sqlite3VdbeCurrentAddr(v);
+    assert( pParse->withinRJSubrtn < 255 );
+    pParse->withinRJSubrtn++;
+
+    /* WHERE clause constraints must be deferred until after outer join
+    ** row elimination has completed, since WHERE clause constraints apply
+    ** to the results of the OUTER JOIN.  The following loop generates the
+    ** appropriate WHERE clause constraint checks.  tag-20220513a.
+    */
+  code_outer_join_constraints:
+    for(pTerm=pWC->a, j=0; j<pWC->nBase; 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;
+      }
+      if( pTabItem->fg.jointype & JT_LTORJ ) continue;
+      assert( pTerm->pExpr );
+      sqlite3ExprIfFalse(pParse, pTerm->pExpr, addrCont, SQLITE_JUMPIFNULL);
+      pTerm->wtFlags |= TERM_CODED;
+    }
+  }
+
+#if WHERETRACE_ENABLED /* 0x4001 */
+  if( sqlite3WhereTrace & 0x4000 ){
+    sqlite3DebugPrintf("All WHERE-clause terms after coding level %d:\n",
+                       iLevel);
+    sqlite3WhereClausePrint(pWC);
+  }
+  if( sqlite3WhereTrace & 0x1 ){
+    sqlite3DebugPrintf("End Coding level %d:  notReady=%llx\n",
+       iLevel, (u64)pLevel->notReady);
+  }
+#endif
+  return pLevel->notReady;
+}
+
+/*
+** Generate the code for the loop that finds all non-matched terms
+** for a RIGHT JOIN.
+*/
+SQLITE_NOINLINE void sqlite3WhereRightJoinLoop(
+  WhereInfo *pWInfo,
+  int iLevel,
+  WhereLevel *pLevel
+){
+  Parse *pParse = pWInfo->pParse;
+  Vdbe *v = pParse->pVdbe;
+  WhereRightJoin *pRJ = pLevel->pRJ;
+  Expr *pSubWhere = 0;
+  WhereClause *pWC = &pWInfo->sWC;
+  WhereInfo *pSubWInfo;
+  WhereLoop *pLoop = pLevel->pWLoop;
+  SrcItem *pTabItem = &pWInfo->pTabList->a[pLevel->iFrom];
+  SrcList sFrom;
+  Bitmask mAll = 0;
+  int k;
+
+  ExplainQueryPlan((pParse, 1, "RIGHT-JOIN %s", pTabItem->pTab->zName));
+  sqlite3VdbeNoJumpsOutsideSubrtn(v, pRJ->addrSubrtn, pRJ->endSubrtn,
+                                  pRJ->regReturn);
+  for(k=0; k<iLevel; k++){
+    int iIdxCur;
+    mAll |= pWInfo->a[k].pWLoop->maskSelf;
+    sqlite3VdbeAddOp1(v, OP_NullRow, pWInfo->a[k].iTabCur);
+    iIdxCur = pWInfo->a[k].iIdxCur;
+    if( iIdxCur ){
+      sqlite3VdbeAddOp1(v, OP_NullRow, iIdxCur);
+    }
+  }
+  if( (pTabItem->fg.jointype & JT_LTORJ)==0 ){
+    mAll |= pLoop->maskSelf;
+    for(k=0; k<pWC->nTerm; k++){
+      WhereTerm *pTerm = &pWC->a[k];
+      if( (pTerm->wtFlags & (TERM_VIRTUAL|TERM_SLICE))!=0
+       && pTerm->eOperator!=WO_ROWVAL
+      ){
+        break;
+      }
+      if( pTerm->prereqAll & ~mAll ) continue;
+      if( ExprHasProperty(pTerm->pExpr, EP_OuterON|EP_InnerON) ) continue;
+      pSubWhere = sqlite3ExprAnd(pParse, pSubWhere,
+                                 sqlite3ExprDup(pParse->db, pTerm->pExpr, 0));
+    }
+  }
+  sFrom.nSrc = 1;
+  sFrom.nAlloc = 1;
+  memcpy(&sFrom.a[0], pTabItem, sizeof(SrcItem));
+  sFrom.a[0].fg.jointype = 0;
+  assert( pParse->withinRJSubrtn < 100 );
+  pParse->withinRJSubrtn++;
+  pSubWInfo = sqlite3WhereBegin(pParse, &sFrom, pSubWhere, 0, 0, 0,
+                                WHERE_RIGHT_JOIN, 0);
+  if( pSubWInfo ){
+    int iCur = pLevel->iTabCur;
+    int r = ++pParse->nMem;
+    int nPk;
+    int jmp;
+    int addrCont = sqlite3WhereContinueLabel(pSubWInfo);
+    Table *pTab = pTabItem->pTab;
+    if( HasRowid(pTab) ){
+      sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, -1, r);
+      nPk = 1;
+    }else{
+      int iPk;
+      Index *pPk = sqlite3PrimaryKeyIndex(pTab);
+      nPk = pPk->nKeyCol;
+      pParse->nMem += nPk - 1;
+      for(iPk=0; iPk<nPk; iPk++){
+        int iCol = pPk->aiColumn[iPk];
+        sqlite3ExprCodeGetColumnOfTable(v, pTab, iCur, iCol,r+iPk);
+      }
+    }
+    jmp = sqlite3VdbeAddOp4Int(v, OP_Filter, pRJ->regBloom, 0, r, nPk);
+    VdbeCoverage(v);
+    sqlite3VdbeAddOp4Int(v, OP_Found, pRJ->iMatch, addrCont, r, nPk);
+    VdbeCoverage(v);
+    sqlite3VdbeJumpHere(v, jmp);
+    sqlite3VdbeAddOp2(v, OP_Gosub, pRJ->regReturn, pRJ->addrSubrtn);
+    sqlite3WhereEnd(pSubWInfo);
+  }
+  sqlite3ExprDelete(pParse->db, pSubWhere);
+  ExplainQueryPlanPop(pParse);
+  assert( pParse->withinRJSubrtn>0 );
+  pParse->withinRJSubrtn--;
+}