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Fix for tickets #3378 and #3381 that preserves the aliasing optimization.

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And yet, this fix feels uncomfortable.  Seeking an alternative... (CVS 5712)

FossilOrigin-Name: f8b759f1977915c314be874840ebf18e6bc69b57
This commit is contained in:
drh
2008-09-17 00:13:12 +00:00
parent f44ed02790
commit d176611b44
5 changed files with 90 additions and 72 deletions
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121
src/select.c
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@@ -12,7 +12,7 @@
** This file contains C code routines that are called by the parser
** to handle SELECT statements in SQLite.
**
** $Id: select.c,v 1.474 2008/09/16 15:55:56 danielk1977 Exp $
** $Id: select.c,v 1.475 2008/09/17 00:13:12 drh Exp $
*/
#include "sqliteInt.h"
@@ -2047,7 +2047,7 @@ static int multiSelectOrderBy(
int labelEnd; /* Label for the end of the overall SELECT stmt */
int j1; /* Jump instructions that get retargetted */
int op; /* One of TK_ALL, TK_UNION, TK_EXCEPT, TK_INTERSECT */
KeyInfo *pKeyDup = 0; /* Comparison information for duplicate removal */
KeyInfo *pKeyDup; /* Comparison information for duplicate removal */
KeyInfo *pKeyMerge; /* Comparison information for merging rows */
sqlite3 *db; /* Database connection */
ExprList *pOrderBy; /* The ORDER BY clause */
@@ -3650,20 +3650,25 @@ int sqlite3Select(
** processed */
int iAbortFlag; /* Mem address which causes query abort if positive */
int groupBySort; /* Rows come from source in GROUP BY order */
int addrEnd; /* End of processing for this SELECT */
/* Remove any and all aliases between the result set and the
** GROUP BY clause.
*/
if( pGroupBy ){
int i; /* Loop counter */
struct ExprList_item *pItem; /* For looping over expression in a list */
/* The following variables hold addresses or labels for parts of the
** virtual machine program we are putting together */
int addrOutputRow; /* Start of subroutine that outputs a result row */
int regOutputRow; /* Return address register for output subroutine */
int addrSetAbort; /* Set the abort flag and return */
int addrInitializeLoop; /* Start of code that initializes the input loop */
int addrTopOfLoop; /* Top of the input loop */
int addrEnd; /* End of all processing */
int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */
int addrReset; /* Subroutine for resetting the accumulator */
int regReset; /* Return address register for reset subroutine */
for(i=p->pEList->nExpr, pItem=p->pEList->a; i>0; i--, pItem++){
pItem->iAlias = 0;
}
for(i=pGroupBy->nExpr, pItem=pGroupBy->a; i>0; i--, pItem++){
pItem->iAlias = 0;
}
}
/* Create a label to jump to when we want to abort the query */
addrEnd = sqlite3VdbeMakeLabel(v);
/* Convert TK_COLUMN nodes into TK_AGG_COLUMN and make entries in
@@ -3692,11 +3697,14 @@ int sqlite3Select(
*/
if( pGroupBy ){
KeyInfo *pKeyInfo; /* Keying information for the group by clause */
int j1;
/* Create labels that we will be needing
*/
addrInitializeLoop = sqlite3VdbeMakeLabel(v);
int j1; /* A-vs-B comparision jump */
int addrOutputRow; /* Start of subroutine that outputs a result row */
int regOutputRow; /* Return address register for output subroutine */
int addrSetAbort; /* Set the abort flag and return */
int addrTopOfLoop; /* Top of the input loop */
int addrSortingIdx; /* The OP_OpenEphemeral for the sorting index */
int addrReset; /* Subroutine for resetting the accumulator */
int regReset; /* Return address register for reset subroutine */
/* If there is a GROUP BY clause we might need a sorting index to
** implement it. Allocate that sorting index now. If it turns out
@@ -3713,6 +3721,10 @@ int sqlite3Select(
*/
iUseFlag = ++pParse->nMem;
iAbortFlag = ++pParse->nMem;
regOutputRow = ++pParse->nMem;
addrOutputRow = sqlite3VdbeMakeLabel(v);
regReset = ++pParse->nMem;
addrReset = sqlite3VdbeMakeLabel(v);
iAMem = pParse->nMem + 1;
pParse->nMem += pGroupBy->nExpr;
iBMem = pParse->nMem + 1;
@@ -3721,47 +3733,12 @@ int sqlite3Select(
VdbeComment((v, "clear abort flag"));
sqlite3VdbeAddOp2(v, OP_Integer, 0, iUseFlag);
VdbeComment((v, "indicate accumulator empty"));
sqlite3VdbeAddOp2(v, OP_Goto, 0, addrInitializeLoop);
/* Generate a subroutine that outputs a single row of the result
** set. This subroutine first looks at the iUseFlag. If iUseFlag
** is less than or equal to zero, the subroutine is a no-op. If
** the processing calls for the query to abort, this subroutine
** increments the iAbortFlag memory location before returning in
** order to signal the caller to abort.
*/
addrSetAbort = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag);
VdbeComment((v, "set abort flag"));
regOutputRow = ++pParse->nMem;
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
addrOutputRow = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
VdbeComment((v, "Groupby result generator entry point"));
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
finalizeAggFunctions(pParse, &sAggInfo);
if( pHaving ){
sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
}
selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy,
distinct, pDest,
addrOutputRow+1, addrSetAbort);
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
VdbeComment((v, "end groupby result generator"));
/* Generate a subroutine that will reset the group-by accumulator
*/
addrReset = sqlite3VdbeCurrentAddr(v);
regReset = ++pParse->nMem;
resetAccumulator(pParse, &sAggInfo);
sqlite3VdbeAddOp1(v, OP_Return, regReset);
/* Begin a loop that will extract all source rows in GROUP BY order.
** This might involve two separate loops with an OP_Sort in between, or
** it might be a single loop that uses an index to extract information
** in the right order to begin with.
*/
sqlite3VdbeResolveLabel(v, addrInitializeLoop);
sqlite3VdbeAddOp2(v, OP_Gosub, regReset, addrReset);
pWInfo = sqlite3WhereBegin(pParse, pTabList, pWhere, &pGroupBy, 0);
if( pWInfo==0 ) goto select_end;
@@ -3879,7 +3856,43 @@ int sqlite3Select(
*/
sqlite3VdbeAddOp2(v, OP_Gosub, regOutputRow, addrOutputRow);
VdbeComment((v, "output final row"));
/* Jump over the subroutines
*/
sqlite3VdbeAddOp2(v, OP_Goto, 0, addrEnd);
/* Generate a subroutine that outputs a single row of the result
** set. This subroutine first looks at the iUseFlag. If iUseFlag
** is less than or equal to zero, the subroutine is a no-op. If
** the processing calls for the query to abort, this subroutine
** increments the iAbortFlag memory location before returning in
** order to signal the caller to abort.
*/
addrSetAbort = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_Integer, 1, iAbortFlag);
VdbeComment((v, "set abort flag"));
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
sqlite3VdbeResolveLabel(v, addrOutputRow);
addrOutputRow = sqlite3VdbeCurrentAddr(v);
sqlite3VdbeAddOp2(v, OP_IfPos, iUseFlag, addrOutputRow+2);
VdbeComment((v, "Groupby result generator entry point"));
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
finalizeAggFunctions(pParse, &sAggInfo);
if( pHaving ){
sqlite3ExprIfFalse(pParse, pHaving, addrOutputRow+1, SQLITE_JUMPIFNULL);
}
selectInnerLoop(pParse, p, p->pEList, 0, 0, pOrderBy,
distinct, pDest,
addrOutputRow+1, addrSetAbort);
sqlite3VdbeAddOp1(v, OP_Return, regOutputRow);
VdbeComment((v, "end groupby result generator"));
/* Generate a subroutine that will reset the group-by accumulator
*/
sqlite3VdbeResolveLabel(v, addrReset);
resetAccumulator(pParse, &sAggInfo);
sqlite3VdbeAddOp1(v, OP_Return, regReset);
} /* endif pGroupBy */
else {
ExprList *pMinMax = 0;