Add the "VALUES-as-coroutine" optimization. Large VALUES clauses on an

INSERT, for example, prepare and run in about half the time and with half
the memory.  This check-in also includes enhancements to the internal
sqlite3ExprIsConstant() routine to recognize pure SQL functions as constant
if they have constant arguments.

FossilOrigin-Name: a120c9235f125e05be494038c16a9dd326fd79837698bef17e7879cd0cd75831

9 files changed, 352 insertions, 68 deletions

diff --git a/src/expr.c b/src/expr.c
index 6640d1907..3a7065b21 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -218,9 +218,10 @@ Expr *sqlite3ExprSkipCollateAndLikely(Expr *pExpr){
       assert( pExpr->x.pList->nExpr>0 );
       assert( pExpr->op==TK_FUNCTION );
       pExpr = pExpr->x.pList->a[0].pExpr;
-    }else{
-      assert( pExpr->op==TK_COLLATE );
+    }else if( pExpr->op==TK_COLLATE ){
       pExpr = pExpr->pLeft;
+    }else{
+      break;
     }
   }  
   return pExpr;
@@ -1869,6 +1870,7 @@ SrcList *sqlite3SrcListDup(sqlite3 *db, const SrcList *p, int flags){
     pNewItem->iCursor = pOldItem->iCursor;
     pNewItem->addrFillSub = pOldItem->addrFillSub;
     pNewItem->regReturn = pOldItem->regReturn;
+    pNewItem->regResult = pOldItem->regResult;
     if( pNewItem->fg.isIndexedBy ){
       pNewItem->u1.zIndexedBy = sqlite3DbStrDup(db, pOldItem->u1.zIndexedBy);
     }
@@ -2345,6 +2347,54 @@ Expr *sqlite3ExprSimplifiedAndOr(Expr *pExpr){
   return pExpr;
 }
 
+/*
+** pExpr is a TK_FUNCTION node.  Try to determine whether or not the
+** function is a constant function.  A function is constant if all of
+** the following are true:
+**
+**    (1)  It is a scalar function (not an aggregate or window function)
+**    (2)  It has either the SQLITE_FUNC_CONSTANT or SQLITE_FUNC_SLOCHNG
+**         property.
+**    (3)  All of its arguments are constants
+**
+** This routine sets pWalker->eCode to 0 if pExpr is not a constant.
+** It makes no changes to pWalker->eCode if pExpr is constant.  In
+** every case, it returns WRC_Abort.
+**
+** Called as a service subroutine from exprNodeIsConstant().
+*/
+static SQLITE_NOINLINE int exprNodeIsConstantFunction(
+  Walker *pWalker,
+  Expr *pExpr
+){
+  int n;             /* Number of arguments */
+  ExprList *pList;   /* List of arguments */
+  FuncDef *pDef;     /* The function */
+  sqlite3 *db;       /* The database */
+
+  assert( pExpr->op==TK_FUNCTION );
+  if( ExprHasProperty(pExpr, EP_TokenOnly)
+   || (pList = pExpr->x.pList)==0
+  ){;
+    n = 0;
+  }else{
+    n = pList->nExpr;
+    sqlite3WalkExprList(pWalker, pList);
+    if( pWalker->eCode==0 ) return WRC_Abort;
+  }
+  db = pWalker->pParse->db;
+  pDef = sqlite3FindFunction(db, pExpr->u.zToken, n, ENC(db), 0);
+  if( pDef==0
+   || pDef->xFinalize!=0
+   || (pDef->funcFlags & (SQLITE_FUNC_CONSTANT|SQLITE_FUNC_SLOCHNG))==0
+   || ExprHasProperty(pExpr, EP_WinFunc)
+  ){
+    pWalker->eCode = 0;
+    return WRC_Abort;
+  }
+  return WRC_Continue;
+}
+
 
 /*
 ** These routines are Walker callbacks used to check expressions to
@@ -2373,6 +2423,7 @@ Expr *sqlite3ExprSimplifiedAndOr(Expr *pExpr){
 ** malformed schema error.
 */
 static int exprNodeIsConstant(Walker *pWalker, Expr *pExpr){
+  assert( pWalker->eCode>0 );
 
   /* If pWalker->eCode is 2 then any term of the expression that comes from
   ** the ON or USING clauses of an outer join disqualifies the expression
@@ -2392,6 +2443,8 @@ static int exprNodeIsConstant(Walker *pWalker, Expr *pExpr){
       ){
         if( pWalker->eCode==5 ) ExprSetProperty(pExpr, EP_FromDDL);
         return WRC_Continue;
+      }else if( pWalker->pParse ){
+        return exprNodeIsConstantFunction(pWalker, pExpr);
       }else{
         pWalker->eCode = 0;
         return WRC_Abort;
@@ -2444,9 +2497,10 @@ static int exprNodeIsConstant(Walker *pWalker, Expr *pExpr){
       return WRC_Continue;
   }
 }
-static int exprIsConst(Expr *p, int initFlag, int iCur){
+static int exprIsConst(Parse *pParse, Expr *p, int initFlag, int iCur){
   Walker w;
   w.eCode = initFlag;
+  w.pParse = pParse;
   w.xExprCallback = exprNodeIsConstant;
   w.xSelectCallback = sqlite3SelectWalkFail;
 #ifdef SQLITE_DEBUG
@@ -2464,9 +2518,15 @@ static int exprIsConst(Expr *p, int initFlag, int iCur){
 ** For the purposes of this function, a double-quoted string (ex: "abc")
 ** is considered a variable but a single-quoted string (ex: 'abc') is
 ** a constant.
+**
+** The pParse parameter may be NULL.  But if it is NULL, there is no way
+** to determine if function calls are constant or not, and hence all
+** function calls will be considered to be non-constant.  If pParse is
+** not NULL, then a function call might be constant, depending on the
+** function and on its parameters.
 */
-int sqlite3ExprIsConstant(Expr *p){
-  return exprIsConst(p, 1, 0);
+int sqlite3ExprIsConstant(Parse *pParse, Expr *p){
+  return exprIsConst(pParse, p, 1, 0);
 }
 
 /*
@@ -2482,8 +2542,8 @@ int sqlite3ExprIsConstant(Expr *p){
 ** can be added to the pParse->pConstExpr list and evaluated once when
 ** the prepared statement starts up.  See sqlite3ExprCodeRunJustOnce().
 */
-int sqlite3ExprIsConstantNotJoin(Expr *p){
-  return exprIsConst(p, 2, 0);
+static int sqlite3ExprIsConstantNotJoin(Parse *pParse, Expr *p){
+  return exprIsConst(pParse, p, 2, 0);
 }
 
 /*
@@ -2493,7 +2553,7 @@ int sqlite3ExprIsConstantNotJoin(Expr *p){
 ** table other than iCur.
 */
 int sqlite3ExprIsTableConstant(Expr *p, int iCur){
-  return exprIsConst(p, 3, iCur);
+  return exprIsConst(0, p, 3, iCur);
 }
 
 /*
@@ -2650,7 +2710,7 @@ int sqlite3ExprIsConstantOrGroupBy(Parse *pParse, Expr *p, ExprList *pGroupBy){
 */
 int sqlite3ExprIsConstantOrFunction(Expr *p, u8 isInit){
   assert( isInit==0 || isInit==1 );
-  return exprIsConst(p, 4+isInit, 0);
+  return exprIsConst(0, p, 4+isInit, 0);
 }
 
 #ifdef SQLITE_ENABLE_CURSOR_HINTS
@@ -2895,13 +2955,13 @@ static void sqlite3SetHasNullFlag(Vdbe *v, int iCur, int regHasNull){
 ** The argument is an IN operator with a list (not a subquery) on the
 ** right-hand side.  Return TRUE if that list is constant.
 */
-static int sqlite3InRhsIsConstant(Expr *pIn){
+static int sqlite3InRhsIsConstant(Parse *pParse, Expr *pIn){
   Expr *pLHS;
   int res;
   assert( !ExprHasProperty(pIn, EP_xIsSelect) );
   pLHS = pIn->pLeft;
   pIn->pLeft = 0;
-  res = sqlite3ExprIsConstant(pIn);
+  res = sqlite3ExprIsConstant(pParse, pIn);
   pIn->pLeft = pLHS;
   return res;
 }
@@ -3170,7 +3230,7 @@ int sqlite3FindInIndex(
   if( eType==0
    && (inFlags & IN_INDEX_NOOP_OK)
    && ExprUseXList(pX)
-   && (!sqlite3InRhsIsConstant(pX) || pX->x.pList->nExpr<=2)
+   && (!sqlite3InRhsIsConstant(pParse,pX) || pX->x.pList->nExpr<=2)
   ){
     pParse->nTab--;  /* Back out the allocation of the unused cursor */
     iTab = -1;       /* Cursor is not allocated */
@@ -3453,7 +3513,7 @@ void sqlite3CodeRhsOfIN(
       ** this code only executes once.  Because for a non-constant
       ** expression we need to rerun this code each time.
       */
-      if( addrOnce && !sqlite3ExprIsConstant(pE2) ){
+      if( addrOnce && !sqlite3ExprIsConstant(pParse, pE2) ){
         sqlite3VdbeChangeToNoop(v, addrOnce-1);
         sqlite3VdbeChangeToNoop(v, addrOnce);
         ExprClearProperty(pExpr, EP_Subrtn);
@@ -4790,7 +4850,9 @@ expr_code_doover:
       }
 #endif
 
-      if( ConstFactorOk(pParse) && sqlite3ExprIsConstantNotJoin(pExpr) ){
+      if( ConstFactorOk(pParse)
+       && sqlite3ExprIsConstantNotJoin(pParse,pExpr)
+      ){
         /* SQL functions can be expensive. So try to avoid running them
         ** multiple times if we know they always give the same result */
         return sqlite3ExprCodeRunJustOnce(pParse, pExpr, -1);
@@ -4821,7 +4883,7 @@ expr_code_doover:
       }
 
       for(i=0; i<nFarg; i++){
-        if( i<32 && sqlite3ExprIsConstant(pFarg->a[i].pExpr) ){
+        if( i<32 && sqlite3ExprIsConstant(pParse, pFarg->a[i].pExpr) ){
           testcase( i==31 );
           constMask |= MASKBIT32(i);
         }
@@ -5288,7 +5350,7 @@ int sqlite3ExprCodeTemp(Parse *pParse, Expr *pExpr, int *pReg){
   if( ConstFactorOk(pParse)
    && ALWAYS(pExpr!=0)
    && pExpr->op!=TK_REGISTER
-   && sqlite3ExprIsConstantNotJoin(pExpr)
+   && sqlite3ExprIsConstantNotJoin(pParse, pExpr)
   ){
     *pReg  = 0;
     r2 = sqlite3ExprCodeRunJustOnce(pParse, pExpr, -1);
@@ -5352,7 +5414,7 @@ void sqlite3ExprCodeCopy(Parse *pParse, Expr *pExpr, int target){
 ** might choose to code the expression at initialization time.
 */
 void sqlite3ExprCodeFactorable(Parse *pParse, Expr *pExpr, int target){
-  if( pParse->okConstFactor && sqlite3ExprIsConstantNotJoin(pExpr) ){
+  if( pParse->okConstFactor && sqlite3ExprIsConstantNotJoin(pParse,pExpr) ){
     sqlite3ExprCodeRunJustOnce(pParse, pExpr, target);
   }else{
     sqlite3ExprCodeCopy(pParse, pExpr, target);
@@ -5411,7 +5473,7 @@ int sqlite3ExprCodeExprList(
         sqlite3VdbeAddOp2(v, copyOp, j+srcReg-1, target+i);
       }
     }else if( (flags & SQLITE_ECEL_FACTOR)!=0
-           && sqlite3ExprIsConstantNotJoin(pExpr)
+           && sqlite3ExprIsConstantNotJoin(pParse,pExpr)
     ){
       sqlite3ExprCodeRunJustOnce(pParse, pExpr, target+i);
     }else{
diff --git a/src/insert.c b/src/insert.c
index 095298b90..fe7ba05dc 100644
--- a/src/insert.c
+++ b/src/insert.c
@@ -577,6 +577,193 @@ void sqlite3AutoincrementEnd(Parse *pParse){
 # define autoIncStep(A,B,C)
 #endif /* SQLITE_OMIT_AUTOINCREMENT */
 
+/*
+** If argument pVal is a Select object returned by an sqlite3MultiValues()
+** that was able to use the co-routine optimization, finish coding the
+** co-routine.
+*/
+void sqlite3MultiValuesEnd(Parse *pParse, Select *pVal){
+  if( ALWAYS(pVal) && pVal->pSrc->nSrc>0 ){
+    SrcItem *pItem = &pVal->pSrc->a[0];
+    sqlite3VdbeEndCoroutine(pParse->pVdbe, pItem->regReturn);
+    sqlite3VdbeJumpHere(pParse->pVdbe, pItem->addrFillSub - 1);
+  }
+}
+
+/*
+** Return true if all expressions in the expression-list passed as the
+** only argument are constant.
+*/
+static int exprListIsConstant(Parse *pParse, ExprList *pRow){
+  int ii;
+  for(ii=0; ii<pRow->nExpr; ii++){
+    if( 0==sqlite3ExprIsConstant(pParse, pRow->a[ii].pExpr) ) return 0;
+  }
+  return 1;
+}
+
+/*
+** Return true if all expressions in the expression-list passed as the
+** only argument are both constant and have no affinity.
+*/
+static int exprListIsNoAffinity(Parse *pParse, ExprList *pRow){
+  int ii;
+  if( exprListIsConstant(pParse,pRow)==0 ) return 0;
+  for(ii=0; ii<pRow->nExpr; ii++){
+    assert( pRow->a[ii].pExpr->affExpr==0 );
+    if( 0!=sqlite3ExprAffinity(pRow->a[ii].pExpr) ) return 0;
+  }
+  return 1;
+
+}
+
+/*
+** This function is called by the parser for the second and subsequent
+** rows of a multi-row VALUES clause. Argument pLeft is the part of
+** the VALUES clause already parsed, argument pRow is the vector of values
+** for the new row. The Select object returned represents the complete
+** VALUES clause, including the new row.
+**
+** There are two ways in which this may be achieved - by incremental 
+** coding of a co-routine (the "co-routine" method) or by returning a
+** Select object equivalent to the following (the "UNION ALL" method):
+**
+**        "pLeft UNION ALL SELECT pRow"
+**
+** If the VALUES clause contains a lot of rows, this compound Select
+** object may consume a lot of memory.
+**
+** When the co-routine method is used, each row that will be returned
+** by the VALUES clause is coded into part of a co-routine as it is 
+** passed to this function. The returned Select object is equivalent to:
+**
+**     SELECT * FROM (
+**       Select object to read co-routine
+**     )
+**
+** The co-routine method is used in most cases. Exceptions are:
+**
+**    a) If the current statement has a WITH clause. This is to avoid
+**       statements like:
+**
+**            WITH cte AS ( VALUES('x'), ('y') ... )
+**            SELECT * FROM cte AS a, cte AS b;
+**
+**       This will not work, as the co-routine uses a hard-coded register
+**       for its OP_Yield instructions, and so it is not possible for two
+**       cursors to iterate through it concurrently.
+**
+**    b) The schema is currently being parsed (i.e. the VALUES clause is part 
+**       of a schema item like a VIEW or TRIGGER). In this case there is no VM
+**       being generated when parsing is taking place, and so generating 
+**       a co-routine is not possible.
+**
+**    c) There are non-constant expressions in the VALUES clause (e.g.
+**       the VALUES clause is part of a correlated sub-query).
+**
+**    d) One or more of the values in the first row of the VALUES clause
+**       has an affinity (i.e. is a CAST expression). This causes problems
+**       because the complex rules SQLite uses (see function 
+**       sqlite3SubqueryColumnTypes() in select.c) to determine the effective
+**       affinity of such a column for all rows require access to all values in
+**       the column simultaneously. 
+*/
+Select *sqlite3MultiValues(Parse *pParse, Select *pLeft, ExprList *pRow){
+
+  if( pParse->bHasWith                   /* condition (a) above */
+   || pParse->db->init.busy              /* condition (b) above */
+   || exprListIsConstant(pParse,pRow)==0 /* condition (c) above */
+   || (pLeft->pSrc->nSrc==0 &&
+       exprListIsNoAffinity(pParse,pLeft->pEList)==0) /* condition (d) above */
+   || IN_SPECIAL_PARSE
+  ){
+    /* The co-routine method cannot be used. Fall back to UNION ALL. */
+    Select *pSelect = 0;
+    int f = SF_Values | SF_MultiValue;
+    if( pLeft->pSrc->nSrc ){
+      sqlite3MultiValuesEnd(pParse, pLeft);
+      f = SF_Values;
+    }else if( pLeft->pPrior ){
+      /* In this case set the SF_MultiValue flag only if it was set on pLeft */
+      f = (f & pLeft->selFlags);
+    }
+    pSelect = sqlite3SelectNew(pParse, pRow, 0, 0, 0, 0, 0, f, 0);
+    pLeft->selFlags &= ~SF_MultiValue;
+    if( pSelect ){
+      pSelect->op = TK_ALL;
+      pSelect->pPrior = pLeft;
+      pLeft = pSelect;
+    }
+  }else{
+    SrcItem *p = 0;               /* SrcItem that reads from co-routine */
+
+    if( pLeft->pSrc->nSrc==0 ){
+      /* Co-routine has not yet been started and the special Select object
+      ** that accesses the co-routine has not yet been created. This block 
+      ** does both those things. */
+      Vdbe *v = sqlite3GetVdbe(pParse);
+      Select *pRet = sqlite3SelectNew(pParse, 0, 0, 0, 0, 0, 0, 0, 0);
+
+      /* Ensure the database schema has been read. This is to ensure we have
+      ** the correct text encoding.  */
+      if( (pParse->db->mDbFlags & DBFLAG_SchemaKnownOk)==0 ){
+        sqlite3ReadSchema(pParse);
+      }
+
+      if( pRet ){
+        SelectDest dest;
+        pRet->pSrc->nSrc = 1;
+        pRet->pPrior = pLeft->pPrior;
+        pRet->op = pLeft->op;
+        pLeft->pPrior = 0;
+        pLeft->op = TK_SELECT;
+        assert( pLeft->pNext==0 );
+        assert( pRet->pNext==0 );
+        p = &pRet->pSrc->a[0];
+        p->pSelect = pLeft;
+        p->fg.viaCoroutine = 1;
+        p->addrFillSub = sqlite3VdbeCurrentAddr(v) + 1;
+        p->regReturn = ++pParse->nMem;
+        p->iCursor = -1;
+        p->u1.nRow = 2;
+        sqlite3VdbeAddOp3(v,OP_InitCoroutine,p->regReturn,0,p->addrFillSub);
+        sqlite3SelectDestInit(&dest, SRT_Coroutine, p->regReturn);
+
+        /* Allocate registers for the output of the co-routine. Do so so
+        ** that there are two unused registers immediately before those
+        ** used by the co-routine. This allows the code in sqlite3Insert()
+        ** to use these registers directly, instead of copying the output
+        ** of the co-routine to a separate array for processing.  */
+        dest.iSdst = pParse->nMem + 3; 
+        dest.nSdst = pLeft->pEList->nExpr;
+        pParse->nMem += 2 + dest.nSdst;
+
+        pLeft->selFlags |= SF_MultiValue;
+        sqlite3Select(pParse, pLeft, &dest);
+        p->regResult = dest.iSdst;
+        assert( pParse->nErr || dest.iSdst>0 );
+        pLeft = pRet;
+      }
+    }else{
+      p = &pLeft->pSrc->a[0];
+      assert( !p->fg.isTabFunc && !p->fg.isIndexedBy );
+      p->u1.nRow++;
+    }
+  
+    if( pParse->nErr==0 ){
+      assert( p!=0 );
+      if( p->pSelect->pEList->nExpr!=pRow->nExpr ){
+        sqlite3SelectWrongNumTermsError(pParse, p->pSelect);
+      }else{
+        sqlite3ExprCodeExprList(pParse, pRow, p->regResult, 0, 0);
+        sqlite3VdbeAddOp1(pParse->pVdbe, OP_Yield, p->regReturn);
+      }
+    }
+    sqlite3ExprListDelete(pParse->db, pRow);
+  }
+
+  return pLeft;
+}
 
 /* Forward declaration */
 static int xferOptimization(
@@ -913,25 +1100,40 @@ void sqlite3Insert(
   if( pSelect ){
     /* Data is coming from a SELECT or from a multi-row VALUES clause.
     ** Generate a co-routine to run the SELECT. */
-    int regYield;       /* Register holding co-routine entry-point */
-    int addrTop;        /* Top of the co-routine */
     int rc;             /* Result code */
 
-    regYield = ++pParse->nMem;
-    addrTop = sqlite3VdbeCurrentAddr(v) + 1;
-    sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, addrTop);
-    sqlite3SelectDestInit(&dest, SRT_Coroutine, regYield);
-    dest.iSdst = bIdListInOrder ? regData : 0;
-    dest.nSdst = pTab->nCol;
-    rc = sqlite3Select(pParse, pSelect, &dest);
-    regFromSelect = dest.iSdst;
-    assert( db->pParse==pParse );
-    if( rc || pParse->nErr ) goto insert_cleanup;
-    assert( db->mallocFailed==0 );
-    sqlite3VdbeEndCoroutine(v, regYield);
-    sqlite3VdbeJumpHere(v, addrTop - 1);                       /* label B: */
-    assert( pSelect->pEList );
-    nColumn = pSelect->pEList->nExpr;
+    if( pSelect->pSrc->nSrc==1 
+     && pSelect->pSrc->a[0].fg.viaCoroutine 
+     && pSelect->pPrior==0
+    ){
+      SrcItem *pItem = &pSelect->pSrc->a[0];
+      dest.iSDParm = pItem->regReturn;
+      regFromSelect = pItem->regResult;
+      nColumn = pItem->pSelect->pEList->nExpr;
+      ExplainQueryPlan((pParse, 0, "SCAN %S", pItem));
+      if( bIdListInOrder && nColumn==pTab->nCol ){
+        regData = regFromSelect;
+        regRowid = regData - 1;
+        regIns = regRowid - (IsVirtual(pTab) ? 1 : 0);
+      }
+    }else{
+      int addrTop;        /* Top of the co-routine */
+      int regYield = ++pParse->nMem;
+      addrTop = sqlite3VdbeCurrentAddr(v) + 1;
+      sqlite3VdbeAddOp3(v, OP_InitCoroutine, regYield, 0, addrTop);
+      sqlite3SelectDestInit(&dest, SRT_Coroutine, regYield);
+      dest.iSdst = bIdListInOrder ? regData : 0;
+      dest.nSdst = pTab->nCol;
+      rc = sqlite3Select(pParse, pSelect, &dest);
+      regFromSelect = dest.iSdst;
+      assert( db->pParse==pParse );
+      if( rc || pParse->nErr ) goto insert_cleanup;
+      assert( db->mallocFailed==0 );
+      sqlite3VdbeEndCoroutine(v, regYield);
+      sqlite3VdbeJumpHere(v, addrTop - 1);                       /* label B: */
+      assert( pSelect->pEList );
+      nColumn = pSelect->pEList->nExpr;
+    }
 
     /* Set useTempTable to TRUE if the result of the SELECT statement
     ** should be written into a temporary table (template 4).  Set to
diff --git a/src/parse.y b/src/parse.y
index 37c9fa8bc..d22c8e6fc 100644
--- a/src/parse.y
+++ b/src/parse.y
@@ -565,6 +565,7 @@ cmd ::= select(X).  {
 select(A) ::= WITH wqlist(W) selectnowith(X). {A = attachWithToSelect(pParse,X,W);}
 select(A) ::= WITH RECURSIVE wqlist(W) selectnowith(X).
                                               {A = attachWithToSelect(pParse,X,W);}
+
 %endif /* SQLITE_OMIT_CTE */
 select(A) ::= selectnowith(A). {
   Select *p = A;
@@ -622,24 +623,27 @@ oneselect(A) ::= SELECT distinct(D) selcollist(W) from(X) where_opt(Y)
 %endif
 
 
-oneselect(A) ::= values(A).
-
+// Single row VALUES clause.
+//
 %type values {Select*}
+oneselect(A) ::= values(A).
 %destructor values {sqlite3SelectDelete(pParse->db, $$);}
 values(A) ::= VALUES LP nexprlist(X) RP. {
   A = sqlite3SelectNew(pParse,X,0,0,0,0,0,SF_Values,0);
 }
-values(A) ::= values(A) COMMA LP nexprlist(Y) RP. {
-  Select *pRight, *pLeft = A;
-  pRight = sqlite3SelectNew(pParse,Y,0,0,0,0,0,SF_Values|SF_MultiValue,0);
-  if( ALWAYS(pLeft) ) pLeft->selFlags &= ~SF_MultiValue;
-  if( pRight ){
-    pRight->op = TK_ALL;
-    pRight->pPrior = pLeft;
-    A = pRight;
-  }else{
-    A = pLeft;
-  }
+
+// Multiple row VALUES clause.
+//
+%type mvalues {Select*}
+oneselect(A) ::= mvalues(A). {
+  sqlite3MultiValuesEnd(pParse, A);
+}
+%destructor mvalues {sqlite3SelectDelete(pParse->db, $$);}
+mvalues(A) ::= values(A) COMMA LP nexprlist(Y) RP. {
+  A = sqlite3MultiValues(pParse, A, Y);
+}
+mvalues(A) ::= mvalues(A) COMMA LP nexprlist(Y) RP. {
+  A = sqlite3MultiValues(pParse, A, Y);
 }
 
 // The "distinct" nonterminal is true (1) if the DISTINCT keyword is
@@ -1321,7 +1325,7 @@ expr(A) ::= expr(A) between_op(N) expr(X) AND expr(Y). [BETWEEN] {
       if( A ) sqlite3ExprIdToTrueFalse(A);
     }else{
       Expr *pRHS = Y->a[0].pExpr;
-      if( Y->nExpr==1 && sqlite3ExprIsConstant(pRHS) && A->op!=TK_VECTOR ){
+      if( Y->nExpr==1 && sqlite3ExprIsConstant(pParse,pRHS) && A->op!=TK_VECTOR ){
         Y->a[0].pExpr = 0;
         sqlite3ExprListDelete(pParse->db, Y);
         pRHS = sqlite3PExpr(pParse, TK_UPLUS, pRHS, 0);
@@ -1761,9 +1765,10 @@ with ::= WITH RECURSIVE wqlist(W).    { sqlite3WithPush(pParse, W, 1); }
 wqas(A)   ::= AS.                  {A = M10d_Any;}
 wqas(A)   ::= AS MATERIALIZED.     {A = M10d_Yes;}
 wqas(A)   ::= AS NOT MATERIALIZED. {A = M10d_No;}
-wqitem(A) ::= nm(X) eidlist_opt(Y) wqas(M) LP select(Z) RP. {
+wqitem(A) ::= withnm(X) eidlist_opt(Y) wqas(M) LP select(Z) RP. {
   A = sqlite3CteNew(pParse, &X, Y, Z, M); /*A-overwrites-X*/
 }
+withnm(A) ::= nm(A). {pParse->bHasWith = 1;}
 wqlist(A) ::= wqitem(X). {
   A = sqlite3WithAdd(pParse, 0, X); /*A-overwrites-X*/
 }
diff --git a/src/printf.c b/src/printf.c
index 186e95bb8..eb22ee320 100644
--- a/src/printf.c
+++ b/src/printf.c
@@ -860,6 +860,10 @@ void sqlite3_str_vappendf(
           assert( pSel!=0 );
           if( pSel->selFlags & SF_NestedFrom ){
             sqlite3_str_appendf(pAccum, "(join-%u)", pSel->selId);
+          }else if( pSel->selFlags & SF_MultiValue ){
+            assert( !pItem->fg.isTabFunc && !pItem->fg.isIndexedBy );
+            sqlite3_str_appendf(pAccum, "%u-ROW VALUES CLAUSE",
+                                pItem->u1.nRow);
           }else{
             sqlite3_str_appendf(pAccum, "(subquery-%u)", pSel->selId);
           }
diff --git a/src/select.c b/src/select.c
index 81e802d6e..1085b9943 100644
--- a/src/select.c
+++ b/src/select.c
@@ -4776,7 +4776,7 @@ static void constInsert(
 ){
   int i;
   assert( pColumn->op==TK_COLUMN );
-  assert( sqlite3ExprIsConstant(pValue) );
+  assert( sqlite3ExprIsConstant(pConst->pParse, pValue) );
 
   if( ExprHasProperty(pColumn, EP_FixedCol) ) return;
   if( sqlite3ExprAffinity(pValue)!=0 ) return;
@@ -4834,10 +4834,10 @@ static void findConstInWhere(WhereConst *pConst, Expr *pExpr){
   pLeft = pExpr->pLeft;
   assert( pRight!=0 );
   assert( pLeft!=0 );
-  if( pRight->op==TK_COLUMN && sqlite3ExprIsConstant(pLeft) ){
+  if( pRight->op==TK_COLUMN && sqlite3ExprIsConstant(pConst->pParse, pLeft) ){
     constInsert(pConst,pRight,pLeft,pExpr);
   }
-  if( pLeft->op==TK_COLUMN && sqlite3ExprIsConstant(pRight) ){
+  if( pLeft->op==TK_COLUMN && sqlite3ExprIsConstant(pConst->pParse, pRight) ){
     constInsert(pConst,pLeft,pRight,pExpr);
   }
 }
@@ -7636,7 +7636,7 @@ int sqlite3Select(
     /* Generate code for all sub-queries in the FROM clause
     */
     pSub = pItem->pSelect;
-    if( pSub==0 ) continue;
+    if( pSub==0 || pItem->addrFillSub!=0 ) continue;
 
     /* The code for a subquery should only be generated once. */
     assert( pItem->addrFillSub==0 );
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index e11b5b3a4..8d18bfdfb 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -3270,10 +3270,12 @@ struct IdList {
 **
 ** Union member validity:
 **
-**    u1.zIndexedBy          fg.isIndexedBy && !fg.isTabFunc
-**    u1.pFuncArg            fg.isTabFunc   && !fg.isIndexedBy
-**    u2.pIBIndex            fg.isIndexedBy && !fg.isCte
-**    u2.pCteUse             fg.isCte       && !fg.isIndexedBy
+**    u1.zIndexedBy      fg.isIndexedBy && !fg.isTabFunc
+**    u1.pFuncArg        fg.isTabFunc   && !fg.isIndexedBy
+**    u1.nRow            !fg.isTabFunc  && !fg.isIndexedBy
+**
+**    u2.pIBIndex        fg.isIndexedBy && !fg.isCte
+**    u2.pCteUse         fg.isCte       && !fg.isIndexedBy
 */
 struct SrcItem {
   Schema *pSchema;  /* Schema to which this item is fixed */
@@ -3311,6 +3313,7 @@ struct SrcItem {
   union {
     char *zIndexedBy;    /* Identifier from "INDEXED BY <zIndex>" clause */
     ExprList *pFuncArg;  /* Arguments to table-valued-function */
+    u32 nRow;            /* Number of rows in a VALUES clause */
   } u1;
   union {
     Index *pIBIndex;  /* Index structure corresponding to u1.zIndexedBy */
@@ -3812,6 +3815,7 @@ struct Parse {
   u8 disableLookaside; /* Number of times lookaside has been disabled */
   u8 prepFlags;        /* SQLITE_PREPARE_* flags */
   u8 withinRJSubrtn;   /* Nesting level for RIGHT JOIN body subroutines */
+  u8 bHasWith;         /* True if statement contains WITH */
 #if defined(SQLITE_DEBUG) || defined(SQLITE_COVERAGE_TEST)
   u8 earlyCleanup;     /* OOM inside sqlite3ParserAddCleanup() */
 #endif
@@ -4486,6 +4490,9 @@ struct Window {
                           ** due to the SQLITE_SUBTYPE flag */
 };
 
+Select *sqlite3MultiValues(Parse *pParse, Select *pLeft, ExprList *pRow);
+void sqlite3MultiValuesEnd(Parse *pParse, Select *pVal);
+
 #ifndef SQLITE_OMIT_WINDOWFUNC
 void sqlite3WindowDelete(sqlite3*, Window*);
 void sqlite3WindowUnlinkFromSelect(Window*);
@@ -5054,8 +5061,7 @@ void sqlite3LeaveMutexAndCloseZombie(sqlite3*);
 u32 sqlite3IsTrueOrFalse(const char*);
 int sqlite3ExprIdToTrueFalse(Expr*);
 int sqlite3ExprTruthValue(const Expr*);
-int sqlite3ExprIsConstant(Expr*);
-int sqlite3ExprIsConstantNotJoin(Expr*);
+int sqlite3ExprIsConstant(Parse*,Expr*);
 int sqlite3ExprIsConstantOrFunction(Expr*, u8);
 int sqlite3ExprIsConstantOrGroupBy(Parse*, Expr*, ExprList*);
 int sqlite3ExprIsTableConstant(Expr*,int);
diff --git a/src/where.c b/src/where.c
index 9850d22cc..2463e823c 100644
--- a/src/where.c
+++ b/src/where.c
@@ -1329,7 +1329,7 @@ static sqlite3_index_info *allocateIndexInfo(
       Expr *pE2;
 
       /* Skip over constant terms in the ORDER BY clause */
-      if( sqlite3ExprIsConstant(pExpr) ){
+      if( sqlite3ExprIsConstant(0, pExpr) ){
         continue;
       }
 
@@ -1441,7 +1441,7 @@ static sqlite3_index_info *allocateIndexInfo(
   pIdxInfo->nConstraint = j;
   for(i=j=0; i<nOrderBy; i++){
     Expr *pExpr = pOrderBy->a[i].pExpr;
-    if( sqlite3ExprIsConstant(pExpr) ) continue;
+    if( sqlite3ExprIsConstant(0, pExpr) ) continue;
     assert( pExpr->op==TK_COLUMN
          || (pExpr->op==TK_COLLATE && pExpr->pLeft->op==TK_COLUMN
               && pExpr->iColumn==pExpr->pLeft->iColumn) );
@@ -3623,7 +3623,7 @@ static void wherePartIdxExpr(
     u8 aff;
 
     if( pLeft->op!=TK_COLUMN ) return;
-    if( !sqlite3ExprIsConstant(pRight) ) return;
+    if( !sqlite3ExprIsConstant(0, pRight) ) return;
     if( !sqlite3IsBinary(sqlite3ExprCompareCollSeq(pParse, pPart)) ) return;
     if( pLeft->iColumn<0 ) return;
     aff = pIdx->pTable->aCol[pLeft->iColumn].affinity;
@@ -4997,7 +4997,7 @@ static i8 wherePathSatisfiesOrderBy(
         if( MASKBIT(i) & obSat ) continue;
         p = pOrderBy->a[i].pExpr;
         mTerm = sqlite3WhereExprUsage(&pWInfo->sMaskSet,p);
-        if( mTerm==0 && !sqlite3ExprIsConstant(p) ) continue;
+        if( mTerm==0 && !sqlite3ExprIsConstant(0,p) ) continue;
         if( (mTerm&~orderDistinctMask)==0 ){
           obSat |= MASKBIT(i);
         }
@@ -5866,7 +5866,7 @@ static SQLITE_NOINLINE void whereAddIndexedExpr(
     }else{
       continue;
     }
-    if( sqlite3ExprIsConstant(pExpr) ) continue;
+    if( sqlite3ExprIsConstant(0,pExpr) ) continue;
     if( pExpr->op==TK_FUNCTION ){
       /* Functions that might set a subtype should not be replaced by the
       ** value taken from an expression index since the index omits the
@@ -6144,7 +6144,11 @@ WhereInfo *sqlite3WhereBegin(
     ){
       pWInfo->eDistinct = WHERE_DISTINCT_UNIQUE;
     }
-    ExplainQueryPlan((pParse, 0, "SCAN CONSTANT ROW"));
+    if( ALWAYS(pWInfo->pSelect)
+     && (pWInfo->pSelect->selFlags & SF_MultiValue)==0
+    ){
+      ExplainQueryPlan((pParse, 0, "SCAN CONSTANT ROW"));
+    }
   }else{
     /* Assign a bit from the bitmask to every term in the FROM clause.
     **
@@ -6896,6 +6900,7 @@ void sqlite3WhereEnd(WhereInfo *pWInfo){
     */
     if( pTabItem->fg.viaCoroutine ){
       testcase( pParse->db->mallocFailed );
+      assert( pTabItem->regResult>=0 );
       translateColumnToCopy(pParse, pLevel->addrBody, pLevel->iTabCur,
                             pTabItem->regResult, 0);
       continue;
diff --git a/src/whereexpr.c b/src/whereexpr.c
index 25db8f396..9d1f947a0 100644
--- a/src/whereexpr.c
+++ b/src/whereexpr.c
@@ -989,7 +989,7 @@ static SQLITE_NOINLINE int exprMightBeIndexed2(
         if( pIdx->aiColumn[i]!=XN_EXPR ) continue;
         assert( pIdx->bHasExpr );
         if( sqlite3ExprCompareSkip(pExpr,pIdx->aColExpr->a[i].pExpr,iCur)==0
-         && !sqlite3ExprIsConstant(pIdx->aColExpr->a[i].pExpr)
+         && !sqlite3ExprIsConstant(0,pIdx->aColExpr->a[i].pExpr)
         ){
           aiCurCol[0] = iCur;
           aiCurCol[1] = XN_EXPR;
diff --git a/src/window.c b/src/window.c
index 62df349fb..bcee65d92 100644
--- a/src/window.c
+++ b/src/window.c
@@ -1164,7 +1164,7 @@ void sqlite3WindowListDelete(sqlite3 *db, Window *p){
 ** variable values in the expression tree.
 */
 static Expr *sqlite3WindowOffsetExpr(Parse *pParse, Expr *pExpr){
-  if( 0==sqlite3ExprIsConstant(pExpr) ){
+  if( 0==sqlite3ExprIsConstant(0,pExpr) ){
     if( IN_RENAME_OBJECT ) sqlite3RenameExprUnmap(pParse, pExpr);
     sqlite3ExprDelete(pParse->db, pExpr);
     pExpr = sqlite3ExprAlloc(pParse->db, TK_NULL, 0, 0);