When an Expr object is changed and that Expr is referenced by an AggInfo, then

also update the AggInfo.  Also, persist all AggInfo objects until the Parse
object is destroyed.  This is a new fix for ticket [c8d3b9f0a750a529] that
avoids the follow-on problems identified by tickets
[0899cf62f597d7e7], [1f6f353b684fc708], [e5504e987e419fb0], and
[f7d890858f361402].

FossilOrigin-Name: 6e6b3729e0549de028f6c5bf494b2d69d621c81b61a1dc0a329d3950039342fb

6 files changed, 187 insertions, 56 deletions

diff --git a/src/build.c b/src/build.c
index 877db0508..03081b965 100644
--- a/src/build.c
+++ b/src/build.c
@@ -207,12 +207,21 @@ void sqlite3FinishCoding(Parse *pParse){
       */
       sqlite3AutoincrementBegin(pParse);
 
-      /* Code constant expressions that where factored out of inner loops */
+      /* Code constant expressions that where factored out of inner loops.
+      **
+      ** The pConstExpr list might also contain expressions that we simply
+      ** want to keep around until the Parse object is deleted.  Such
+      ** expressions have iConstExprReg==0.  Do not generate code for
+      ** those expressions, of course.
+      */
       if( pParse->pConstExpr ){
         ExprList *pEL = pParse->pConstExpr;
         pParse->okConstFactor = 0;
         for(i=0; i<pEL->nExpr; i++){
-          sqlite3ExprCode(pParse, pEL->a[i].pExpr, pEL->a[i].u.iConstExprReg);
+          int iReg = pEL->a[i].u.iConstExprReg;
+          if( iReg>0 ){
+            sqlite3ExprCode(pParse, pEL->a[i].pExpr, iReg);
+          }
         }
       }
 
diff --git a/src/expr.c b/src/expr.c
index 496177a5c..6fbc8bb49 100644
--- a/src/expr.c
+++ b/src/expr.c
@@ -52,7 +52,12 @@ char sqlite3ExprAffinity(const Expr *pExpr){
   op = pExpr->op;
   if( op==TK_SELECT ){
     assert( pExpr->flags&EP_xIsSelect );
-    return sqlite3ExprAffinity(pExpr->x.pSelect->pEList->a[0].pExpr);
+    if( ALWAYS(pExpr->x.pSelect)
+     && pExpr->x.pSelect->pEList
+     && ALWAYS(pExpr->x.pSelect->pEList->a[0].pExpr)
+    ){
+      return sqlite3ExprAffinity(pExpr->x.pSelect->pEList->a[0].pExpr);
+    }
   }
   if( op==TK_REGISTER ) op = pExpr->op2;
 #ifndef SQLITE_OMIT_CAST
@@ -5710,6 +5715,64 @@ int sqlite3FunctionUsesThisSrc(Expr *pExpr, SrcList *pSrcList){
 }
 
 /*
+** This is a Walker expression node callback.
+**
+** For Expr nodes that contain pAggInfo pointers, make sure the AggInfo
+** object that is referenced does not refer directly to the Expr.  If
+** it does, make a copy.  This is done because the pExpr argument is
+** subject to change.
+**
+** The copy is stored on pParse->pConstExpr with a register number of 0.
+** This will cause the expression to be deleted automatically when the
+** Parse object is destroyed, but the zero register number means that it
+** will not generate any code in the preamble.
+*/
+static int agginfoPersistExprCb(Walker *pWalker, Expr *pExpr){
+  if( ALWAYS(!ExprHasProperty(pExpr, EP_TokenOnly|EP_Reduced))
+   && pExpr->pAggInfo!=0
+  ){
+    AggInfo *pAggInfo = pExpr->pAggInfo;
+    int iAgg = pExpr->iAgg;
+    Parse *pParse = pWalker->pParse;
+    sqlite3 *db = pParse->db;
+    assert( pExpr->op==TK_AGG_COLUMN || pExpr->op==TK_AGG_FUNCTION );
+    if( pExpr->op==TK_AGG_COLUMN ){
+      assert( iAgg>=0 && iAgg<pAggInfo->nColumn );
+      if( pAggInfo->aCol[iAgg].pExpr==pExpr ){
+        pExpr = sqlite3ExprDup(db, pExpr, 0);
+        if( pExpr ){
+          pAggInfo->aCol[iAgg].pExpr = pExpr;
+          pParse->pConstExpr = 
+             sqlite3ExprListAppend(pParse, pParse->pConstExpr, pExpr);
+        }
+      }
+    }else{
+      assert( iAgg>=0 && iAgg<pAggInfo->nFunc );
+      if( pAggInfo->aFunc[iAgg].pExpr==pExpr ){
+        pExpr = sqlite3ExprDup(db, pExpr, 0);
+        if( pExpr ){
+          pAggInfo->aFunc[iAgg].pExpr = pExpr;
+          pParse->pConstExpr = 
+             sqlite3ExprListAppend(pParse, pParse->pConstExpr, pExpr);
+        }
+      }
+    }
+  }
+  return WRC_Continue;
+}
+
+/*
+** Initialize a Walker object so that will persist AggInfo entries referenced
+** by the tree that is walked.
+*/
+void sqlite3AggInfoPersistWalkerInit(Walker *pWalker, Parse *pParse){
+  memset(pWalker, 0, sizeof(*pWalker));
+  pWalker->pParse = pParse;
+  pWalker->xExprCallback = agginfoPersistExprCb;
+  pWalker->xSelectCallback = sqlite3SelectWalkNoop;
+}
+
+/*
 ** Add a new element to the pAggInfo->aCol[] array.  Return the index of
 ** the new element.  Return a negative number if malloc fails.
 */
@@ -5739,7 +5802,7 @@ static int addAggInfoFunc(sqlite3 *db, AggInfo *pInfo){
        &i
   );
   return i;
-}    
+}
 
 /*
 ** This is the xExprCallback for a tree walker.  It is used to
diff --git a/src/prepare.c b/src/prepare.c
index 259954676..c63c0a835 100644
--- a/src/prepare.c
+++ b/src/prepare.c
@@ -531,10 +531,25 @@ int sqlite3SchemaToIndex(sqlite3 *db, Schema *pSchema){
 }
 
 /*
+** Deallocate a single AggInfo object
+*/
+static void agginfoFree(sqlite3 *db, AggInfo *p){
+  sqlite3DbFree(db, p->aCol);
+  sqlite3DbFree(db, p->aFunc);
+  sqlite3DbFree(db, p);
+}
+
+/*
 ** Free all memory allocations in the pParse object
 */
 void sqlite3ParserReset(Parse *pParse){
   sqlite3 *db = pParse->db;
+  AggInfo *pThis = pParse->pAggList;
+  while( pThis ){
+    AggInfo *pNext = pThis->pNext;
+    agginfoFree(db, pThis);
+    pThis = pNext;
+  }
   sqlite3DbFree(db, pParse->aLabel);
   sqlite3ExprListDelete(db, pParse->pConstExpr);
   if( db ){
diff --git a/src/select.c b/src/select.c
index 7ff2b5d34..9e8af0cb1 100644
--- a/src/select.c
+++ b/src/select.c
@@ -3791,6 +3791,7 @@ static int flattenSubquery(
   Expr *pWhere;                    /* The WHERE clause */
   struct SrcList_item *pSubitem;   /* The subquery */
   sqlite3 *db = pParse->db;
+  Walker w;                        /* Walker to persist agginfo data */
 
   /* Check to see if flattening is permitted.  Return 0 if not.
   */
@@ -4165,6 +4166,8 @@ static int flattenSubquery(
   /* Finially, delete what is left of the subquery and return
   ** success.
   */
+  sqlite3AggInfoPersistWalkerInit(&w, pParse);
+  sqlite3WalkSelect(&w,pSub1);
   sqlite3SelectDelete(db, pSub1);
 
 #if SELECTTRACE_ENABLED
@@ -5749,10 +5752,10 @@ int sqlite3Select(
   Expr *pWhere;          /* The WHERE clause.  May be NULL */
   ExprList *pGroupBy;    /* The GROUP BY clause.  May be NULL */
   Expr *pHaving;         /* The HAVING clause.  May be NULL */
+  AggInfo *pAggInfo = 0; /* Aggregate information */
   int rc = 1;            /* Value to return from this function */
   DistinctCtx sDistinct; /* Info on how to code the DISTINCT keyword */
   SortCtx sSort;         /* Info on how to code the ORDER BY clause */
-  AggInfo sAggInfo;      /* Information used by aggregate queries */
   int iEnd;              /* Address of the end of the query */
   sqlite3 *db;           /* The database connection */
   ExprList *pMinMaxOrderBy = 0;  /* Added ORDER BY for min/max queries */
@@ -5764,7 +5767,6 @@ int sqlite3Select(
     return 1;
   }
   if( sqlite3AuthCheck(pParse, SQLITE_SELECT, 0, 0, 0) ) return 1;
-  memset(&sAggInfo, 0, sizeof(sAggInfo));
 #if SELECTTRACE_ENABLED
   SELECTTRACE(1,pParse,p, ("begin processing:\n", pParse->addrExplain));
   if( sqlite3SelectTrace & 0x100 ){
@@ -6354,14 +6356,20 @@ int sqlite3Select(
     ** sAggInfo for all TK_AGG_FUNCTION nodes in expressions of the
     ** SELECT statement.
     */
+    pAggInfo = sqlite3DbMallocZero(db, sizeof(*pAggInfo) );
+    if( pAggInfo==0 ){
+      goto select_end;
+    }
+    pAggInfo->pNext = pParse->pAggList;
+    pParse->pAggList = pAggInfo;
     memset(&sNC, 0, sizeof(sNC));
     sNC.pParse = pParse;
     sNC.pSrcList = pTabList;
-    sNC.uNC.pAggInfo = &sAggInfo;
+    sNC.uNC.pAggInfo = pAggInfo;
     VVA_ONLY( sNC.ncFlags = NC_UAggInfo; )
-    sAggInfo.mnReg = pParse->nMem+1;
-    sAggInfo.nSortingColumn = pGroupBy ? pGroupBy->nExpr : 0;
-    sAggInfo.pGroupBy = pGroupBy;
+    pAggInfo->mnReg = pParse->nMem+1;
+    pAggInfo->nSortingColumn = pGroupBy ? pGroupBy->nExpr : 0;
+    pAggInfo->pGroupBy = pGroupBy;
     sqlite3ExprAnalyzeAggList(&sNC, pEList);
     sqlite3ExprAnalyzeAggList(&sNC, sSort.pOrderBy);
     if( pHaving ){
@@ -6374,14 +6382,14 @@ int sqlite3Select(
       }
       sqlite3ExprAnalyzeAggregates(&sNC, pHaving);
     }
-    sAggInfo.nAccumulator = sAggInfo.nColumn;
-    if( p->pGroupBy==0 && p->pHaving==0 && sAggInfo.nFunc==1 ){
-      minMaxFlag = minMaxQuery(db, sAggInfo.aFunc[0].pExpr, &pMinMaxOrderBy);
+    pAggInfo->nAccumulator = pAggInfo->nColumn;
+    if( p->pGroupBy==0 && p->pHaving==0 && pAggInfo->nFunc==1 ){
+      minMaxFlag = minMaxQuery(db, pAggInfo->aFunc[0].pExpr, &pMinMaxOrderBy);
     }else{
       minMaxFlag = WHERE_ORDERBY_NORMAL;
     }
-    for(i=0; i<sAggInfo.nFunc; i++){
-      Expr *pExpr = sAggInfo.aFunc[i].pExpr;
+    for(i=0; i<pAggInfo->nFunc; i++){
+      Expr *pExpr = pAggInfo->aFunc[i].pExpr;
       assert( !ExprHasProperty(pExpr, EP_xIsSelect) );
       sNC.ncFlags |= NC_InAggFunc;
       sqlite3ExprAnalyzeAggList(&sNC, pExpr->x.pList);
@@ -6393,22 +6401,22 @@ int sqlite3Select(
 #endif
       sNC.ncFlags &= ~NC_InAggFunc;
     }
-    sAggInfo.mxReg = pParse->nMem;
+    pAggInfo->mxReg = pParse->nMem;
     if( db->mallocFailed ) goto select_end;
 #if SELECTTRACE_ENABLED
     if( sqlite3SelectTrace & 0x400 ){
       int ii;
-      SELECTTRACE(0x400,pParse,p,("After aggregate analysis %p:\n", &sAggInfo));
+      SELECTTRACE(0x400,pParse,p,("After aggregate analysis %p:\n", pAggInfo));
       sqlite3TreeViewSelect(0, p, 0);
-      for(ii=0; ii<sAggInfo.nColumn; ii++){
+      for(ii=0; ii<pAggInfo->nColumn; ii++){
         sqlite3DebugPrintf("agg-column[%d] iMem=%d\n",
-            ii, sAggInfo.aCol[ii].iMem);
-        sqlite3TreeViewExpr(0, sAggInfo.aCol[ii].pExpr, 0);
+            ii, pAggInfo->aCol[ii].iMem);
+        sqlite3TreeViewExpr(0, pAggInfo->aCol[ii].pExpr, 0);
       }
-      for(ii=0; ii<sAggInfo.nFunc; ii++){
+      for(ii=0; ii<pAggInfo->nFunc; ii++){
         sqlite3DebugPrintf("agg-func[%d]: iMem=%d\n",
-            ii, sAggInfo.aFunc[ii].iMem);
-        sqlite3TreeViewExpr(0, sAggInfo.aFunc[ii].pExpr, 0);
+            ii, pAggInfo->aFunc[ii].iMem);
+        sqlite3TreeViewExpr(0, pAggInfo->aFunc[ii].pExpr, 0);
       }
     }
 #endif
@@ -6433,10 +6441,11 @@ int sqlite3Select(
       ** that we do not need it after all, the OP_SorterOpen instruction
       ** will be converted into a Noop.  
       */
-      sAggInfo.sortingIdx = pParse->nTab++;
-      pKeyInfo = sqlite3KeyInfoFromExprList(pParse,pGroupBy,0,sAggInfo.nColumn);
+      pAggInfo->sortingIdx = pParse->nTab++;
+      pKeyInfo = sqlite3KeyInfoFromExprList(pParse, pGroupBy,
+                                            0, pAggInfo->nColumn);
       addrSortingIdx = sqlite3VdbeAddOp4(v, OP_SorterOpen, 
-          sAggInfo.sortingIdx, sAggInfo.nSortingColumn, 
+          pAggInfo->sortingIdx, pAggInfo->nSortingColumn, 
           0, (char*)pKeyInfo, P4_KEYINFO);
 
       /* Initialize memory locations used by GROUP BY aggregate processing
@@ -6491,8 +6500,8 @@ int sqlite3Select(
         nGroupBy = pGroupBy->nExpr;
         nCol = nGroupBy;
         j = nGroupBy;
-        for(i=0; i<sAggInfo.nColumn; i++){
-          if( sAggInfo.aCol[i].iSorterColumn>=j ){
+        for(i=0; i<pAggInfo->nColumn; i++){
+          if( pAggInfo->aCol[i].iSorterColumn>=j ){
             nCol++;
             j++;
           }
@@ -6500,8 +6509,8 @@ int sqlite3Select(
         regBase = sqlite3GetTempRange(pParse, nCol);
         sqlite3ExprCodeExprList(pParse, pGroupBy, regBase, 0, 0);
         j = nGroupBy;
-        for(i=0; i<sAggInfo.nColumn; i++){
-          struct AggInfo_col *pCol = &sAggInfo.aCol[i];
+        for(i=0; i<pAggInfo->nColumn; i++){
+          struct AggInfo_col *pCol = &pAggInfo->aCol[i];
           if( pCol->iSorterColumn>=j ){
             int r1 = j + regBase;
             sqlite3ExprCodeGetColumnOfTable(v,
@@ -6511,16 +6520,16 @@ int sqlite3Select(
         }
         regRecord = sqlite3GetTempReg(pParse);
         sqlite3VdbeAddOp3(v, OP_MakeRecord, regBase, nCol, regRecord);
-        sqlite3VdbeAddOp2(v, OP_SorterInsert, sAggInfo.sortingIdx, regRecord);
+        sqlite3VdbeAddOp2(v, OP_SorterInsert, pAggInfo->sortingIdx, regRecord);
         sqlite3ReleaseTempReg(pParse, regRecord);
         sqlite3ReleaseTempRange(pParse, regBase, nCol);
         sqlite3WhereEnd(pWInfo);
-        sAggInfo.sortingIdxPTab = sortPTab = pParse->nTab++;
+        pAggInfo->sortingIdxPTab = sortPTab = pParse->nTab++;
         sortOut = sqlite3GetTempReg(pParse);
         sqlite3VdbeAddOp3(v, OP_OpenPseudo, sortPTab, sortOut, nCol);
-        sqlite3VdbeAddOp2(v, OP_SorterSort, sAggInfo.sortingIdx, addrEnd);
+        sqlite3VdbeAddOp2(v, OP_SorterSort, pAggInfo->sortingIdx, addrEnd);
         VdbeComment((v, "GROUP BY sort")); VdbeCoverage(v);
-        sAggInfo.useSortingIdx = 1;
+        pAggInfo->useSortingIdx = 1;
       }
 
       /* If the index or temporary table used by the GROUP BY sort
@@ -6544,14 +6553,14 @@ int sqlite3Select(
       */
       addrTopOfLoop = sqlite3VdbeCurrentAddr(v);
       if( groupBySort ){
-        sqlite3VdbeAddOp3(v, OP_SorterData, sAggInfo.sortingIdx,
+        sqlite3VdbeAddOp3(v, OP_SorterData, pAggInfo->sortingIdx,
                           sortOut, sortPTab);
       }
       for(j=0; j<pGroupBy->nExpr; j++){
         if( groupBySort ){
           sqlite3VdbeAddOp3(v, OP_Column, sortPTab, j, iBMem+j);
         }else{
-          sAggInfo.directMode = 1;
+          pAggInfo->directMode = 1;
           sqlite3ExprCode(pParse, pGroupBy->a[j].pExpr, iBMem+j);
         }
       }
@@ -6581,14 +6590,14 @@ int sqlite3Select(
       ** the current row
       */
       sqlite3VdbeJumpHere(v, addr1);
-      updateAccumulator(pParse, iUseFlag, &sAggInfo);
+      updateAccumulator(pParse, iUseFlag, pAggInfo);
       sqlite3VdbeAddOp2(v, OP_Integer, 1, iUseFlag);
       VdbeComment((v, "indicate data in accumulator"));
 
       /* End of the loop
       */
       if( groupBySort ){
-        sqlite3VdbeAddOp2(v, OP_SorterNext, sAggInfo.sortingIdx, addrTopOfLoop);
+        sqlite3VdbeAddOp2(v, OP_SorterNext, pAggInfo->sortingIdx, addrTopOfLoop);
         VdbeCoverage(v);
       }else{
         sqlite3WhereEnd(pWInfo);
@@ -6621,7 +6630,7 @@ int sqlite3Select(
       VdbeCoverage(v);
       VdbeComment((v, "Groupby result generator entry point"));
       sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
-      finalizeAggFunctions(pParse, &sAggInfo);
+      finalizeAggFunctions(pParse, pAggInfo);
       sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
       selectInnerLoop(pParse, p, -1, &sSort,
                       &sDistinct, pDest,
@@ -6632,7 +6641,7 @@ int sqlite3Select(
       /* Generate a subroutine that will reset the group-by accumulator
       */
       sqlite3VdbeResolveLabel(v, addrReset);
-      resetAccumulator(pParse, &sAggInfo);
+      resetAccumulator(pParse, pAggInfo);
       sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
       VdbeComment((v, "indicate accumulator empty"));
       sqlite3VdbeAddOp1(v, OP_Return, regReset);
@@ -6640,7 +6649,7 @@ int sqlite3Select(
     } /* endif pGroupBy.  Begin aggregate queries without GROUP BY: */
     else {
       Table *pTab;
-      if( (pTab = isSimpleCount(p, &sAggInfo))!=0 ){
+      if( (pTab = isSimpleCount(p, pAggInfo))!=0 ){
         /* If isSimpleCount() returns a pointer to a Table structure, then
         ** the SQL statement is of the form:
         **
@@ -6695,7 +6704,7 @@ int sqlite3Select(
         if( pKeyInfo ){
           sqlite3VdbeChangeP4(v, -1, (char *)pKeyInfo, P4_KEYINFO);
         }
-        sqlite3VdbeAddOp2(v, OP_Count, iCsr, sAggInfo.aFunc[0].iMem);
+        sqlite3VdbeAddOp2(v, OP_Count, iCsr, pAggInfo->aFunc[0].iMem);
         sqlite3VdbeAddOp1(v, OP_Close, iCsr);
         explainSimpleCount(pParse, pTab, pBest);
       }else{
@@ -6710,12 +6719,16 @@ int sqlite3Select(
         ** first row visited by the aggregate, so that they are updated at
         ** least once even if the FILTER clause means the min() or max() 
         ** function visits zero rows.  */
-        if( sAggInfo.nAccumulator ){
-          for(i=0; i<sAggInfo.nFunc; i++){
-            if( ExprHasProperty(sAggInfo.aFunc[i].pExpr, EP_WinFunc) ) continue;
-            if( sAggInfo.aFunc[i].pFunc->funcFlags&SQLITE_FUNC_NEEDCOLL ) break;
+        if( pAggInfo->nAccumulator ){
+          for(i=0; i<pAggInfo->nFunc; i++){
+            if( ExprHasProperty(pAggInfo->aFunc[i].pExpr, EP_WinFunc) ){
+              continue;
+            }
+            if( pAggInfo->aFunc[i].pFunc->funcFlags&SQLITE_FUNC_NEEDCOLL ){
+              break;
+            }
           }
-          if( i==sAggInfo.nFunc ){
+          if( i==pAggInfo->nFunc ){
             regAcc = ++pParse->nMem;
             sqlite3VdbeAddOp2(v, OP_Integer, 0, regAcc);
           }
@@ -6726,7 +6739,7 @@ int sqlite3Select(
         ** of output.
         */
         assert( p->pGroupBy==0 );
-        resetAccumulator(pParse, &sAggInfo);
+        resetAccumulator(pParse, pAggInfo);
 
         /* If this query is a candidate for the min/max optimization, then
         ** minMaxFlag will have been previously set to either
@@ -6742,7 +6755,7 @@ int sqlite3Select(
         if( pWInfo==0 ){
           goto select_end;
         }
-        updateAccumulator(pParse, regAcc, &sAggInfo);
+        updateAccumulator(pParse, regAcc, pAggInfo);
         if( regAcc ) sqlite3VdbeAddOp2(v, OP_Integer, 1, regAcc);
         if( sqlite3WhereIsOrdered(pWInfo)>0 ){
           sqlite3VdbeGoto(v, sqlite3WhereBreakLabel(pWInfo));
@@ -6750,7 +6763,7 @@ int sqlite3Select(
                 (minMaxFlag==WHERE_ORDERBY_MIN?"min":"max")));
         }
         sqlite3WhereEnd(pWInfo);
-        finalizeAggFunctions(pParse, &sAggInfo);
+        finalizeAggFunctions(pParse, pAggInfo);
       }
 
       sSort.pOrderBy = 0;
@@ -6789,8 +6802,25 @@ int sqlite3Select(
   */
 select_end:
   sqlite3ExprListDelete(db, pMinMaxOrderBy);
-  sqlite3DbFree(db, sAggInfo.aCol);
-  sqlite3DbFree(db, sAggInfo.aFunc);
+#ifdef SQLITE_DEBUG
+  if( pAggInfo ){
+    for(i=0; i<pAggInfo->nColumn; i++){
+      Expr *pExpr = pAggInfo->aCol[i].pExpr;
+      assert( pExpr!=0 || db->mallocFailed );
+      if( pExpr==0 ) continue;
+      assert( pExpr->pAggInfo==pAggInfo );
+      assert( pExpr->iAgg==i );
+    }
+    for(i=0; i<pAggInfo->nFunc; i++){
+      Expr *pExpr = pAggInfo->aFunc[i].pExpr;
+      assert( pExpr!=0 || db->mallocFailed );
+      if( pExpr==0 ) continue;
+      assert( pExpr->pAggInfo==pAggInfo );
+      assert( pExpr->iAgg==i );
+    }
+  }
+#endif
+
 #if SELECTTRACE_ENABLED
   SELECTTRACE(0x1,pParse,p,("end processing\n"));
   if( (sqlite3SelectTrace & 0x2000)!=0 && ExplainQueryPlanParent(pParse)==0 ){
diff --git a/src/sqliteInt.h b/src/sqliteInt.h
index e37ed673a..0b71ef42b 100644
--- a/src/sqliteInt.h
+++ b/src/sqliteInt.h
@@ -2506,11 +2506,11 @@ struct AggInfo {
   ExprList *pGroupBy;     /* The group by clause */
   struct AggInfo_col {    /* For each column used in source tables */
     Table *pTab;             /* Source table */
+    Expr *pExpr;             /* The original expression */
     int iTable;              /* Cursor number of the source table */
-    int iColumn;             /* Column number within the source table */
-    int iSorterColumn;       /* Column number in the sorting index */
     int iMem;                /* Memory location that acts as accumulator */
-    Expr *pExpr;             /* The original expression */
+    i16 iColumn;             /* Column number within the source table */
+    i16 iSorterColumn;       /* Column number in the sorting index */
   } *aCol;
   int nColumn;            /* Number of used entries in aCol[] */
   int nAccumulator;       /* Number of columns that show through to the output.
@@ -2523,9 +2523,18 @@ struct AggInfo {
     int iDistinct;           /* Ephemeral table used to enforce DISTINCT */
   } *aFunc;
   int nFunc;              /* Number of entries in aFunc[] */
+#ifdef SQLITE_DEBUG
+  int iAggMagic;          /* Magic number when valid */
+#endif
+  AggInfo *pNext;         /* Next in list of them all */
 };
 
 /*
+** Value for AggInfo.iAggMagic when the structure is valid
+*/
+#define AggInfoMagic  0x2059e99e
+
+/*
 ** The datatype ynVar is a signed integer, either 16-bit or 32-bit.
 ** Usually it is 16-bits.  But if SQLITE_MAX_VARIABLE_NUMBER is greater
 ** than 32767 we have to make it 32-bit.  16-bit is preferred because
@@ -3321,6 +3330,7 @@ struct Parse {
   Parse *pToplevel;    /* Parse structure for main program (or NULL) */
   Table *pTriggerTab;  /* Table triggers are being coded for */
   Parse *pParentParse; /* Parent parser if this parser is nested */
+  AggInfo *pAggList;   /* List of all AggInfo objects */
   int addrCrTab;       /* Address of OP_CreateBtree opcode on CREATE TABLE */
   u32 nQueryLoop;      /* Est number of iterations of a query (10*log2(N)) */
   u32 oldmask;         /* Mask of old.* columns referenced */
@@ -4287,6 +4297,7 @@ int sqlite3ExprCompareSkip(Expr*, Expr*, int);
 int sqlite3ExprListCompare(ExprList*, ExprList*, int);
 int sqlite3ExprImpliesExpr(Parse*,Expr*, Expr*, int);
 int sqlite3ExprImpliesNonNullRow(Expr*,int);
+void sqlite3AggInfoPersistWalkerInit(Walker*,Parse*);
 void sqlite3ExprAnalyzeAggregates(NameContext*, Expr*);
 void sqlite3ExprAnalyzeAggList(NameContext*,ExprList*);
 int sqlite3ExprCoveredByIndex(Expr*, int iCur, Index *pIdx);
diff --git a/src/window.c b/src/window.c
index 77ec8a02e..8046e4627 100644
--- a/src/window.c
+++ b/src/window.c
@@ -956,12 +956,16 @@ int sqlite3WindowRewrite(Parse *pParse, Select *p){
     Window *pMWin = p->pWin;      /* Master window object */
     Window *pWin;                 /* Window object iterator */
     Table *pTab;
+    Walker w;
+
     u32 selFlags = p->selFlags;
 
     pTab = sqlite3DbMallocZero(db, sizeof(Table));
     if( pTab==0 ){
       return sqlite3ErrorToParser(db, SQLITE_NOMEM);
     }
+    sqlite3AggInfoPersistWalkerInit(&w, pParse);
+    sqlite3WalkSelect(&w, p);
 
     p->pSrc = 0;
     p->pWhere = 0;
@@ -1042,7 +1046,6 @@ int sqlite3WindowRewrite(Parse *pParse, Select *p){
     p->pSrc = sqlite3SrcListAppend(pParse, 0, 0, 0);
     if( p->pSrc ){
       Table *pTab2;
-      Walker w;
       p->pSrc->a[0].pSelect = pSub;
       sqlite3SrcListAssignCursors(pParse, p->pSrc);
       pSub->selFlags |= SF_Expanded;