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Fix for bugs #77 and #80: Rework the LIMIT mechanism to be reentrant and to

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clean up the VDBE stack properly. (CVS 636)

FossilOrigin-Name: 9d5523107937e3700c76666fb058694babdd672c
This commit is contained in:
drh
2002-06-21 23:01:49 +00:00
parent 7aa128dbc5
commit d11d382c99
8 changed files with 218 additions and 189 deletions
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35
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 1.95 2002/06/20 03:38:26 drh Exp $
** $Id: select.c,v 1.96 2002/06/21 23:01:50 drh Exp $
*/
#include "sqliteInt.h"
@@ -334,10 +334,12 @@ static int selectInnerLoop(
*/
if( pOrderBy==0 ){
if( p->nOffset>0 ){
sqliteVdbeAddOp(v, OP_LimitCk, 1, iContinue);
int addr = sqliteVdbeCurrentAddr(v);
sqliteVdbeAddOp(v, OP_MemIncr, p->nOffset, addr+2);
sqliteVdbeAddOp(v, OP_Goto, 0, iContinue);
}
if( p->nLimit>0 ){
sqliteVdbeAddOp(v, OP_LimitCk, 0, iBreak);
if( p->nLimit>=0 ){
sqliteVdbeAddOp(v, OP_MemIncr, p->nLimit, iBreak);
}
}
@@ -483,10 +485,12 @@ static void generateSortTail(
sqliteVdbeAddOp(v, OP_Sort, 0, 0);
addr = sqliteVdbeAddOp(v, OP_SortNext, 0, end);
if( p->nOffset>0 ){
sqliteVdbeAddOp(v, OP_LimitCk, 1, addr);
sqliteVdbeAddOp(v, OP_MemIncr, p->nOffset, addr+4);
sqliteVdbeAddOp(v, OP_Pop, 1, 0);
sqliteVdbeAddOp(v, OP_Goto, 0, addr);
}
if( p->nLimit>0 ){
sqliteVdbeAddOp(v, OP_LimitCk, 0, end);
if( p->nLimit>=0 ){
sqliteVdbeAddOp(v, OP_MemIncr, p->nLimit, end);
}
switch( eDest ){
case SRT_Callback: {
@@ -1305,7 +1309,7 @@ int flattenSubquery(Select *p, int iFrom, int isAgg, int subqueryIsAgg){
if( (pSub->isDistinct || pSub->nLimit>=0) && (pSrc->nSrc>1 || isAgg) ){
return 0;
}
if( (p->isDistinct || p->nLimit) && subqueryIsAgg ) return 0;
if( (p->isDistinct || p->nLimit>=0) && subqueryIsAgg ) return 0;
/* If we reach this point, it means flattening is permitted for the
** i-th entry of the FROM clause in the outer query.
@@ -1722,10 +1726,21 @@ int sqliteSelect(
/* Set the limiter
*/
if( p->nLimit<=0 ){
p->nLimit = -1;
p->nOffset = 0;
}else{
if( p->nOffset<0 ) p->nOffset = 0;
sqliteVdbeAddOp(v, OP_Limit, p->nLimit, p->nOffset);
int iMem = pParse->nMem++;
sqliteVdbeAddOp(v, OP_Integer, -p->nLimit, 0);
sqliteVdbeAddOp(v, OP_MemStore, iMem, 0);
p->nLimit = iMem;
if( p->nOffset<=0 ){
p->nOffset = 0;
}else{
iMem = pParse->nMem++;
sqliteVdbeAddOp(v, OP_Integer, -p->nOffset, 0);
sqliteVdbeAddOp(v, OP_MemStore, iMem, 0);
p->nOffset = iMem;
}
}
/* Generate code for all sub-queries in the FROM clause