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Get LIMIT and OFFSET working again for negative limits and offsets.

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Ticket #1586. (CVS 2889)

FossilOrigin-Name: b2ac0be07ec76ab23b7e5b800c0bc62d0bc97f4b
This commit is contained in:
drh
2006-01-08 18:10:17 +00:00
parent 6f58f7069b
commit 15007a99e4
8 changed files with 97 additions and 57 deletions
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61
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 1.287 2006/01/08 05:02:55 drh Exp $
** $Id: select.c,v 1.288 2006/01/08 18:10:18 drh Exp $
*/
#include "sqliteInt.h"
@@ -363,14 +363,14 @@ static void pushOntoSorter(
sqlite3VdbeAddOp(v, OP_MakeRecord, pOrderBy->nExpr + 2, 0);
sqlite3VdbeAddOp(v, OP_IdxInsert, pOrderBy->iECursor, 0);
if( pSelect->iLimit>=0 ){
int addr1;
sqlite3VdbeAddOp(v, OP_MemIncr, pSelect->iLimit+1, 0);
addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, pSelect->iLimit+1, 0);
sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
int addr1, addr2;
addr1 = sqlite3VdbeAddOp(v, OP_IfMemZero, pSelect->iLimit+1, 0);
sqlite3VdbeAddOp(v, OP_MemIncr, -1, pSelect->iLimit+1);
addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
sqlite3VdbeJumpHere(v, addr1);
sqlite3VdbeAddOp(v, OP_Last, pOrderBy->iECursor, 0);
sqlite3VdbeAddOp(v, OP_Delete, pOrderBy->iECursor, 0);
sqlite3VdbeJumpHere(v, addr1+1);
sqlite3VdbeJumpHere(v, addr2);
pSelect->iLimit = -1;
}
}
@@ -385,15 +385,15 @@ static void codeOffset(
int nPop /* Number of times to pop stack when jumping */
){
if( p->iOffset>=0 && iContinue!=0 ){
int addr = sqlite3VdbeCurrentAddr(v) + 3;
if( nPop>0 ) addr++;
sqlite3VdbeAddOp(v, OP_MemIncr, p->iOffset, 0);
sqlite3VdbeAddOp(v, OP_IfMemPos, p->iOffset, addr);
int addr;
sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iOffset);
addr = sqlite3VdbeAddOp(v, OP_IfMemNeg, p->iOffset, addr);
if( nPop>0 ){
sqlite3VdbeAddOp(v, OP_Pop, nPop, 0);
}
sqlite3VdbeAddOp(v, OP_Goto, 0, iContinue);
VdbeComment((v, "# skip OFFSET records"));
sqlite3VdbeJumpHere(v, addr);
}
}
@@ -617,7 +617,7 @@ static int selectInnerLoop(
/* Jump to the end of the loop if the LIMIT is reached.
*/
if( p->iLimit>=0 && pOrderBy==0 ){
sqlite3VdbeAddOp(v, OP_MemIncr, p->iLimit, 0);
sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, iBreak);
}
return 0;
@@ -739,7 +739,7 @@ static void generateSortTail(
/* Jump to the end of the loop when the LIMIT is reached
*/
if( p->iLimit>=0 ){
sqlite3VdbeAddOp(v, OP_MemIncr, p->iLimit, 0);
sqlite3VdbeAddOp(v, OP_MemIncr, -1, p->iLimit);
sqlite3VdbeAddOp(v, OP_IfMemZero, p->iLimit, brk);
}
@@ -1365,6 +1365,7 @@ Vdbe *sqlite3GetVdbe(Parse *pParse){
return v;
}
/*
** Compute the iLimit and iOffset fields of the SELECT based on the
** pLimit and pOffset expressions. pLimit and pOffset hold the expressions
@@ -1384,6 +1385,11 @@ Vdbe *sqlite3GetVdbe(Parse *pParse){
** SELECT statements.
*/
static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
Vdbe *v;
int iLimit;
int iOffset;
int addr1, addr2;
/*
** "LIMIT -1" always shows all rows. There is some
** contraversy about what the correct behavior should be.
@@ -1391,36 +1397,41 @@ static void computeLimitRegisters(Parse *pParse, Select *p, int iBreak){
** no rows.
*/
if( p->pLimit ){
int iMem = pParse->nMem;
p->iLimit = iLimit = pParse->nMem;
pParse->nMem += 2;
Vdbe *v = sqlite3GetVdbe(pParse);
v = sqlite3GetVdbe(pParse);
if( v==0 ) return;
sqlite3ExprCode(pParse, p->pLimit);
sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
sqlite3VdbeAddOp(v, OP_Negative, 0, 0);
sqlite3VdbeAddOp(v, OP_MemStore, iMem, 0);
sqlite3VdbeAddOp(v, OP_MemStore, iLimit, 0);
VdbeComment((v, "# LIMIT counter"));
sqlite3VdbeAddOp(v, OP_IfMemZero, iMem, iBreak);
p->iLimit = iMem;
sqlite3VdbeAddOp(v, OP_IfMemZero, iLimit, iBreak);
}
if( p->pOffset ){
int iMem = pParse->nMem++;
Vdbe *v = sqlite3GetVdbe(pParse);
p->iOffset = iOffset = pParse->nMem++;
v = sqlite3GetVdbe(pParse);
if( v==0 ) return;
sqlite3ExprCode(pParse, p->pOffset);
sqlite3VdbeAddOp(v, OP_MustBeInt, 0, 0);
sqlite3VdbeAddOp(v, OP_Negative, 0, 0);
sqlite3VdbeAddOp(v, OP_MemStore, iMem, p->pLimit==0);
sqlite3VdbeAddOp(v, OP_MemStore, iOffset, p->pLimit==0);
VdbeComment((v, "# OFFSET counter"));
addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, iOffset, 0);
sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
sqlite3VdbeAddOp(v, OP_Integer, 0, 0);
sqlite3VdbeJumpHere(v, addr1);
if( p->pLimit ){
sqlite3VdbeAddOp(v, OP_Add, 0, 0);
}
p->iOffset = iMem;
}
if( p->pLimit ){
Vdbe *v = pParse->pVdbe;
sqlite3VdbeAddOp(v, OP_MemStore, p->iLimit+1, 1);
addr1 = sqlite3VdbeAddOp(v, OP_IfMemPos, iLimit, 0);
sqlite3VdbeAddOp(v, OP_Pop, 1, 0);
sqlite3VdbeAddOp(v, OP_MemInt, -1, iLimit+1);
addr2 = sqlite3VdbeAddOp(v, OP_Goto, 0, 0);
sqlite3VdbeJumpHere(v, addr1);
sqlite3VdbeAddOp(v, OP_MemStore, iLimit+1, 1);
VdbeComment((v, "# LIMIT+OFFSET"));
sqlite3VdbeJumpHere(v, addr2);
}
}