The generalized indexed expression optimization of [2435112867fbd7b6] makes

the prior [a47efb7c8520a011] enhancement from 2017 obsolete.  This check-in
removes the older optimization.

FossilOrigin-Name: 56442c9bdd7844454c79acf83323380ea3509cb2e0b9a3d538a6b51726ae6d07

7 files changed, 26 insertions, 224 deletions

diff --git a/src/expr.c b/src/expr.c
index 1a743ee5c..7a4e59f28 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -55,9 +55,8 @@ char sqlite3ExprAffinity(const Expr *pExpr){
   if( op==TK_REGISTER ) op = pExpr->op2;
   if( op==TK_COLUMN || op==TK_AGG_COLUMN ){
     assert( ExprUseYTab(pExpr) );
-    if( pExpr->y.pTab ){
-      return sqlite3TableColumnAffinity(pExpr->y.pTab, pExpr->iColumn);
-    }
+    assert( pExpr->y.pTab!=0 );
+    return sqlite3TableColumnAffinity(pExpr->y.pTab, pExpr->iColumn);
   }
   if( op==TK_SELECT ){
     assert( ExprUseXSelect(pExpr) );
@@ -175,17 +174,14 @@ CollSeq *sqlite3ExprCollSeq(Parse *pParse, const Expr *pExpr){
     int op = p->op;
     if( op==TK_REGISTER ) op = p->op2;
     if( op==TK_AGG_COLUMN || op==TK_COLUMN || op==TK_TRIGGER ){
+      int j;
       assert( ExprUseYTab(p) );
-      if( p->y.pTab!=0 ){
-        /* op==TK_REGISTER && p->y.pTab!=0 happens when pExpr was originally
-        ** a TK_COLUMN but was previously evaluated and cached in a register */
-        int j = p->iColumn;
-        if( j>=0 ){
-          const char *zColl = sqlite3ColumnColl(&p->y.pTab->aCol[j]);
-          pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
-        }
-        break;
+      assert( p->y.pTab!=0 );
+      if( (j = p->iColumn)>=0 ){
+        const char *zColl = sqlite3ColumnColl(&p->y.pTab->aCol[j]);
+        pColl = sqlite3FindCollSeq(db, ENC(db), zColl, 0);
       }
+      break;
     }
     if( op==TK_CAST || op==TK_UPLUS ){
       p = p->pLeft;
@@ -3790,10 +3786,7 @@ void sqlite3ExprCodeGetColumnOfTable(
 ){
   Column *pCol;
   assert( v!=0 );
-  if( pTab==0 ){
-    sqlite3VdbeAddOp3(v, OP_Column, iTabCur, iCol, regOut);
-    return;
-  }
+  assert( pTab!=0 );
   if( iCol<0 || iCol==pTab->iPKey ){
     sqlite3VdbeAddOp2(v, OP_Rowid, iTabCur, regOut);
     VdbeComment((v, "%s.rowid", pTab->zName));
@@ -4168,11 +4161,8 @@ expr_code_doover:
         int aff;
         iReg = sqlite3ExprCodeTarget(pParse, pExpr->pLeft,target);
         assert( ExprUseYTab(pExpr) );
-        if( pExpr->y.pTab ){
-          aff = sqlite3TableColumnAffinity(pExpr->y.pTab, pExpr->iColumn);
-        }else{
-          aff = pExpr->affExpr;
-        }
+        assert( pExpr->y.pTab!=0 );
+        aff = sqlite3TableColumnAffinity(pExpr->y.pTab, pExpr->iColumn);
         if( aff>SQLITE_AFF_BLOB ){
           static const char zAff[] = "B\000C\000D\000E";
           assert( SQLITE_AFF_BLOB=='A' );
@@ -4234,12 +4224,10 @@ expr_code_doover:
         }
       }
       assert( ExprUseYTab(pExpr) );
+      assert( pExpr->y.pTab!=0 );
       iReg = sqlite3ExprCodeGetColumn(pParse, pExpr->y.pTab,
                                pExpr->iColumn, iTab, target,
                                pExpr->op2);
-      if( pExpr->y.pTab==0 && pExpr->affExpr==SQLITE_AFF_REAL ){
-        sqlite3VdbeAddOp1(v, OP_RealAffinity, iReg);
-      }
       return iReg;
     }
     case TK_INTEGER: {
@@ -5930,10 +5918,10 @@ static int impliesNotNullRow(Walker *pWalker, Expr *pExpr){
       assert( pLeft->op!=TK_COLUMN || ExprUseYTab(pLeft) );
       assert( pRight->op!=TK_COLUMN || ExprUseYTab(pRight) );
       if( (pLeft->op==TK_COLUMN
-           && pLeft->y.pTab!=0
+           && ALWAYS(pLeft->y.pTab!=0)
            && IsVirtual(pLeft->y.pTab))
        || (pRight->op==TK_COLUMN
-           && pRight->y.pTab!=0
+           && ALWAYS(pRight->y.pTab!=0)
            && IsVirtual(pRight->y.pTab))
       ){
         return WRC_Prune;
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index a437cc0d2..2159ec848 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -2361,7 +2361,7 @@ struct Table {
 #ifndef SQLITE_OMIT_VIRTUALTABLE
 #  define IsVirtual(X)      ((X)->eTabType==TABTYP_VTAB)
 #  define ExprIsVtab(X)  \
-    ((X)->op==TK_COLUMN && (X)->y.pTab!=0 && (X)->y.pTab->eTabType==TABTYP_VTAB)
+   ((X)->op==TK_COLUMN && (X)->y.pTab->eTabType==TABTYP_VTAB)
 #else
 #  define IsVirtual(X)      0
 #  define ExprIsVtab(X)     0
diff --git a/src/vtab.c b/src/vtab.c
index 9bf031faf..3814b0355 100644
--- a/src/vtab.c
+++ b/src/vtab.c
@@ -1141,7 +1141,7 @@ FuncDef *sqlite3VtabOverloadFunction(
   if( pExpr->op!=TK_COLUMN ) return pDef;
   assert( ExprUseYTab(pExpr) );
   pTab = pExpr->y.pTab;
-  if( pTab==0 ) return pDef;
+  if( NEVER(pTab==0) ) return pDef;
   if( !IsVirtual(pTab) ) return pDef;
   pVtab = sqlite3GetVTable(db, pTab)->pVtab;
   assert( pVtab!=0 );
diff --git a/src/where.c b/src/where.c
index 8c65dc7b0..905c3391e 100644
--- a/src/where.c
+++ b/src/where.c
@@ -2287,7 +2287,6 @@ static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
     pWInfo->pLoops = p->pNextLoop;
     whereLoopDelete(db, p);
   }
-  assert( pWInfo->pExprMods==0 );
   while( pWInfo->pMemToFree ){
     WhereMemBlock *pNext = pWInfo->pMemToFree->pNext;
     sqlite3DbNNFreeNN(db, pWInfo->pMemToFree);
@@ -2296,17 +2295,6 @@ static void whereInfoFree(sqlite3 *db, WhereInfo *pWInfo){
   sqlite3DbNNFreeNN(db, pWInfo);
 }
 
-/* Undo all Expr node modifications
-*/
-static void whereUndoExprMods(WhereInfo *pWInfo){
-  while( pWInfo->pExprMods ){
-    WhereExprMod *p = pWInfo->pExprMods;
-    pWInfo->pExprMods = p->pNext;
-    memcpy(p->pExpr, &p->orig, sizeof(p->orig));
-    sqlite3DbFree(pWInfo->pParse->db, p);
-  }
-}
-
 /*
 ** Return TRUE if all of the following are true:
 **
@@ -5608,7 +5596,9 @@ WhereInfo *sqlite3WhereBegin(
   pWInfo->pParse = pParse;
   pWInfo->pTabList = pTabList;
   pWInfo->pOrderBy = pOrderBy;
+#if WHERETRACE_ENABLED
   pWInfo->pWhere = pWhere;
+#endif
   pWInfo->pResultSet = pResultSet;
   pWInfo->aiCurOnePass[0] = pWInfo->aiCurOnePass[1] = -1;
   pWInfo->nLevel = nTabList;
@@ -6115,8 +6105,6 @@ WhereInfo *sqlite3WhereBegin(
   /* Jump here if malloc fails */
 whereBeginError:
   if( pWInfo ){
-    testcase( pWInfo->pExprMods!=0 );
-    whereUndoExprMods(pWInfo);
     pParse->nQueryLoop = pWInfo->savedNQueryLoop;
     whereInfoFree(db, pWInfo);
   }
@@ -6335,7 +6323,6 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
   }
 
   assert( pWInfo->nLevel<=pTabList->nSrc );
-  if( pWInfo->pExprMods ) whereUndoExprMods(pWInfo);
   for(i=0, pLevel=pWInfo->a; i<pWInfo->nLevel; i++, pLevel++){
     int k, last;
     VdbeOp *pOp, *pLastOp;
diff --git a/src/whereInt.h b/src/whereInt.h
index 43da5c208..ae436e045 100644
--- a/src/whereInt.h
+++ b/src/whereInt.h
@@ -450,20 +450,6 @@ struct WhereLoopBuilder {
 #endif
 
 /*
-** Each instance of this object records a change to a single node
-** in an expression tree to cause that node to point to a column
-** of an index rather than an expression or a virtual column.  All
-** such transformations need to be undone at the end of WHERE clause
-** processing.
-*/
-typedef struct WhereExprMod WhereExprMod;
-struct WhereExprMod {
-  WhereExprMod *pNext;  /* Next translation on a list of them all */
-  Expr *pExpr;          /* The Expr node that was transformed */
-  Expr orig;            /* Original value of the Expr node */
-};
-
-/*
 ** The WHERE clause processing routine has two halves.  The
 ** first part does the start of the WHERE loop and the second
 ** half does the tail of the WHERE loop.  An instance of
@@ -478,7 +464,9 @@ struct WhereInfo {
   SrcList *pTabList;        /* List of tables in the join */
   ExprList *pOrderBy;       /* The ORDER BY clause or NULL */
   ExprList *pResultSet;     /* Result set of the query */
+#if WHERETRACE_ENABLED
   Expr *pWhere;             /* The complete WHERE clause */
+#endif
 #ifndef SQLITE_OMIT_VIRTUALTABLE
   Select *pLimit;           /* Used to access LIMIT expr/registers for vtabs */
 #endif
@@ -500,7 +488,6 @@ struct WhereInfo {
   int iTop;                 /* The very beginning of the WHERE loop */
   int iEndWhere;            /* End of the WHERE clause itself */
   WhereLoop *pLoops;        /* List of all WhereLoop objects */
-  WhereExprMod *pExprMods;  /* Expression modifications */
   WhereMemBlock *pMemToFree;/* Memory to free when this object destroyed */
   Bitmask revMask;          /* Mask of ORDER BY terms that need reversing */
   WhereClause sWC;          /* Decomposition of the WHERE clause */
diff --git a/src/wherecode.c b/src/wherecode.c
index c2e7278d1..a1ecf93b8 100644
--- a/src/wherecode.c
+++ b/src/wherecode.c
@@ -1217,143 +1217,6 @@ static void codeExprOrVector(Parse *pParse, Expr *p, int iReg, int nReg){
   }
 }
 
-/* An instance of the IdxExprTrans object carries information about a
-** mapping from an expression on table columns into a column in an index
-** down through the Walker.
-*/
-typedef struct IdxExprTrans {
-  Expr *pIdxExpr;    /* The index expression */
-  int iTabCur;       /* The cursor of the corresponding table */
-  int iIdxCur;       /* The cursor for the index */
-  int iIdxCol;       /* The column for the index */
-  int iTabCol;       /* The column for the table */
-  WhereInfo *pWInfo; /* Complete WHERE clause information */
-  sqlite3 *db;       /* Database connection (for malloc()) */
-} IdxExprTrans;
-
-/*
-** Preserve pExpr on the WhereETrans list of the WhereInfo.
-*/
-static void preserveExpr(IdxExprTrans *pTrans, Expr *pExpr){
-  WhereExprMod *pNew;
-  pNew = sqlite3DbMallocRaw(pTrans->db, sizeof(*pNew));
-  if( pNew==0 ) return;
-  pNew->pNext = pTrans->pWInfo->pExprMods;
-  pTrans->pWInfo->pExprMods = pNew;
-  pNew->pExpr = pExpr;
-  memcpy(&pNew->orig, pExpr, sizeof(*pExpr));
-}
-
-/* The walker node callback used to transform matching expressions into
-** a reference to an index column for an index on an expression.
-**
-** If pExpr matches, then transform it into a reference to the index column
-** that contains the value of pExpr.
-*/
-static int whereIndexExprTransNode(Walker *p, Expr *pExpr){
-  IdxExprTrans *pX = p->u.pIdxTrans;
-  if( sqlite3ExprCompare(0, pExpr, pX->pIdxExpr, pX->iTabCur)==0 ){
-    pExpr = sqlite3ExprSkipCollate(pExpr);
-    preserveExpr(pX, pExpr);
-    pExpr->affExpr = sqlite3ExprAffinity(pExpr);
-    pExpr->op = TK_COLUMN;
-    pExpr->iTable = pX->iIdxCur;
-    pExpr->iColumn = pX->iIdxCol;
-    testcase( ExprHasProperty(pExpr, EP_Unlikely) );
-    ExprClearProperty(pExpr, EP_Skip|EP_Unlikely|EP_WinFunc|EP_Subrtn);
-    pExpr->y.pTab = 0;
-    return WRC_Prune;
-  }else{
-    return WRC_Continue;
-  }
-}
-
-#ifndef SQLITE_OMIT_GENERATED_COLUMNS
-/* A walker node callback that translates a column reference to a table
-** into a corresponding column reference of an index.
-*/
-static int whereIndexExprTransColumn(Walker *p, Expr *pExpr){
-  if( pExpr->op==TK_COLUMN ){
-    IdxExprTrans *pX = p->u.pIdxTrans;
-    if( pExpr->iTable==pX->iTabCur && pExpr->iColumn==pX->iTabCol ){
-      assert( ExprUseYTab(pExpr) && pExpr->y.pTab!=0 );
-      preserveExpr(pX, pExpr);
-      pExpr->affExpr = sqlite3TableColumnAffinity(pExpr->y.pTab,pExpr->iColumn);
-      pExpr->iTable = pX->iIdxCur;
-      pExpr->iColumn = pX->iIdxCol;
-      pExpr->y.pTab = 0;
-    }
-  }
-  return WRC_Continue;
-}
-#endif /* SQLITE_OMIT_GENERATED_COLUMNS */
-
-/*
-** For an indexes on expression X, locate every instance of expression X
-** in pExpr and change that subexpression into a reference to the appropriate
-** column of the index.
-**
-** 2019-10-24: Updated to also translate references to a VIRTUAL column in
-** the table into references to the corresponding (stored) column of the
-** index.
-*/
-static void whereIndexExprTrans(
-  Index *pIdx,      /* The Index */
-  int iTabCur,      /* Cursor of the table that is being indexed */
-  int iIdxCur,      /* Cursor of the index itself */
-  WhereInfo *pWInfo /* Transform expressions in this WHERE clause */
-){
-  int iIdxCol;               /* Column number of the index */
-  ExprList *aColExpr;        /* Expressions that are indexed */
-  Table *pTab;
-  Walker w;
-  IdxExprTrans x;
-  aColExpr = pIdx->aColExpr;
-  if( aColExpr==0 && !pIdx->bHasVCol ){
-    /* The index does not reference any expressions or virtual columns
-    ** so no translations are needed. */
-    return;
-  }
-  pTab = pIdx->pTable;
-  memset(&w, 0, sizeof(w));
-  w.u.pIdxTrans = &x;
-  x.iTabCur = iTabCur;
-  x.iIdxCur = iIdxCur;
-  x.pWInfo = pWInfo;
-  x.db = pWInfo->pParse->db;
-  for(iIdxCol=0; iIdxCol<pIdx->nColumn; iIdxCol++){
-    i16 iRef = pIdx->aiColumn[iIdxCol];
-    if( iRef==XN_EXPR ){
-      assert( aColExpr!=0 && aColExpr->a[iIdxCol].pExpr!=0 );
-      x.pIdxExpr = aColExpr->a[iIdxCol].pExpr;
-      if( sqlite3ExprIsConstant(x.pIdxExpr) ) continue;
-      w.xExprCallback = whereIndexExprTransNode;
-#ifndef SQLITE_OMIT_GENERATED_COLUMNS
-    }else if( iRef>=0
-       && (pTab->aCol[iRef].colFlags & COLFLAG_VIRTUAL)!=0
-       && ((pTab->aCol[iRef].colFlags & COLFLAG_HASCOLL)==0
-           || sqlite3StrICmp(sqlite3ColumnColl(&pTab->aCol[iRef]),
-                                               sqlite3StrBINARY)==0)
-    ){
-      /* Check to see if there are direct references to generated columns
-      ** that are contained in the index.  Pulling the generated column
-      ** out of the index is an optimization only - the main table is always
-      ** available if the index cannot be used.  To avoid unnecessary
-      ** complication, omit this optimization if the collating sequence for
-      ** the column is non-standard */
-      x.iTabCol = iRef;
-      w.xExprCallback = whereIndexExprTransColumn;
-#endif /* SQLITE_OMIT_GENERATED_COLUMNS */
-    }else{
-      continue;
-    }
-    x.iIdxCol = iIdxCol;
-    sqlite3WalkExpr(&w, pWInfo->pWhere);
-    sqlite3WalkExprList(&w, pWInfo->pOrderBy);
-    sqlite3WalkExprList(&w, pWInfo->pResultSet);
-  }
-}
-
 /*
 ** 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
@@ -2181,27 +2044,6 @@ Bitmask sqlite3WhereCodeOneLoopStart(
     }
 
     if( pLevel->iLeftJoin==0 ){
-      /* If pIdx is an index on one or more expressions, then look through
-      ** all the expressions in pWInfo and try to transform matching expressions
-      ** into reference to index columns.  Also attempt to translate references
-      ** to virtual columns in the table into references to (stored) columns
-      ** of the index.
-      **
-      ** Do not do this for the RHS of a LEFT JOIN. This is because the 
-      ** expression may be evaluated after OP_NullRow has been executed on
-      ** the cursor. In this case it is important to do the full evaluation,
-      ** as the result of the expression may not be NULL, even if all table
-      ** column values are.  https://www.sqlite.org/src/info/7fa8049685b50b5a
-      **
-      ** Also, do not do this when processing one index an a multi-index
-      ** OR clause, since the transformation will become invalid once we
-      ** move forward to the next index.
-      ** https://sqlite.org/src/info/4e8e4857d32d401f
-      */
-      if( (pWInfo->wctrlFlags & (WHERE_OR_SUBCLAUSE|WHERE_RIGHT_JOIN))==0 ){
-        whereIndexExprTrans(pIdx, iCur, iIdxCur, pWInfo);
-      }
-  
       /* 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.
diff --git a/src/whereexpr.c b/src/whereexpr.c
index 20e569642..9fe779120 100644
--- a/src/whereexpr.c
+++ b/src/whereexpr.c
@@ -266,7 +266,7 @@ static int isLikeOrGlob(
         if( pLeft->op!=TK_COLUMN 
          || sqlite3ExprAffinity(pLeft)!=SQLITE_AFF_TEXT 
          || (ALWAYS( ExprUseYTab(pLeft) )
-             && pLeft->y.pTab
+             && ALWAYS(pLeft->y.pTab)
              && IsVirtual(pLeft->y.pTab))  /* Might be numeric */
         ){
           int isNum;
@@ -383,8 +383,7 @@ static int isAuxiliaryVtabOperator(
     **       MATCH(expression,vtab_column)
     */
     pCol = pList->a[1].pExpr;
-    assert( pCol->op!=TK_COLUMN || ExprUseYTab(pCol) );
-    testcase( pCol->op==TK_COLUMN && pCol->y.pTab==0 );
+    assert( pCol->op!=TK_COLUMN || (ExprUseYTab(pCol) && pCol->y.pTab!=0) );
     if( ExprIsVtab(pCol) ){
       for(i=0; i<ArraySize(aOp); i++){
         assert( !ExprHasProperty(pExpr, EP_IntValue) );
@@ -409,7 +408,7 @@ static int isAuxiliaryVtabOperator(
     */
     pCol = pList->a[0].pExpr;
     assert( pCol->op!=TK_COLUMN || ExprUseYTab(pCol) );
-    testcase( pCol->op==TK_COLUMN && pCol->y.pTab==0 );
+    assert( pCol->op!=TK_COLUMN || (ExprUseYTab(pCol) && pCol->y.pTab!=0) );
     if( ExprIsVtab(pCol) ){
       sqlite3_vtab *pVtab;
       sqlite3_module *pMod;
@@ -434,13 +433,12 @@ static int isAuxiliaryVtabOperator(
     int res = 0;
     Expr *pLeft = pExpr->pLeft;
     Expr *pRight = pExpr->pRight;
-    assert( pLeft->op!=TK_COLUMN || ExprUseYTab(pLeft) );
-    testcase( pLeft->op==TK_COLUMN && pLeft->y.pTab==0 );
+    assert( pLeft->op!=TK_COLUMN || (ExprUseYTab(pLeft) && pLeft->y.pTab!=0) );
     if( ExprIsVtab(pLeft) ){
       res++;
     }
-    assert( pRight==0 || pRight->op!=TK_COLUMN || ExprUseYTab(pRight) );
-    testcase( pRight && pRight->op==TK_COLUMN && pRight->y.pTab==0 );
+    assert( pRight==0 || pRight->op!=TK_COLUMN
+            || (ExprUseYTab(pRight) && pRight->y.pTab!=0) );
     if( pRight && ExprIsVtab(pRight) ){
       res++;
       SWAP(Expr*, pLeft, pRight);