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More efficient handling of the LIMIT clause. Scalar subqueries and EXISTS

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on compound SELECT statements now working properly.  Ticket #1473. (CVS 2747)

FossilOrigin-Name: edca8913ca012fc0c17343a27f819de95147b1bd
This commit is contained in:
drh
2005-10-06 16:53:14 +00:00
parent 23cc57f6a3
commit ec7429ae27
9 changed files with 829 additions and 69 deletions
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20
src/expr.c
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@@ -12,7 +12,7 @@
** This file contains routines used for analyzing expressions and
** for generating VDBE code that evaluates expressions in SQLite.
**
** $Id: expr.c,v 1.230 2005/09/23 21:11:54 drh Exp $
** $Id: expr.c,v 1.231 2005/10/06 16:53:15 drh Exp $
*/
#include "sqliteInt.h"
#include <ctype.h>
@@ -1390,21 +1390,25 @@ void sqlite3CodeSubselect(Parse *pParse, Expr *pExpr){
** value of this select in a memory cell and record the number
** of the memory cell in iColumn.
*/
int sop;
static const Token one = { "1", 0, 1 };
Select *pSel;
int iMem;
int sop;
pExpr->iColumn = pParse->nMem++;
pExpr->iColumn = iMem = pParse->nMem++;
pSel = pExpr->pSelect;
if( pExpr->op==TK_SELECT ){
sop = SRT_Mem;
sqlite3VdbeAddOp(v, OP_MemNull, iMem, 0);
VdbeComment((v, "# Init subquery result"));
}else{
static const Token one = { "1", 0, 1 };
sop = SRT_Exists;
sqlite3ExprListDelete(pSel->pEList);
pSel->pEList = sqlite3ExprListAppend(0,
sqlite3Expr(TK_INTEGER, 0, 0, &one), 0);
sqlite3VdbeAddOp(v, OP_MemInt, 0, iMem);
VdbeComment((v, "# Init EXISTS result"));
}
sqlite3Select(pParse, pSel, sop, pExpr->iColumn, 0, 0, 0, 0);
sqlite3ExprDelete(pSel->pLimit);
pSel->pLimit = sqlite3Expr(TK_INTEGER, 0, 0, &one);
sqlite3Select(pParse, pSel, sop, iMem, 0, 0, 0, 0);
break;
}
}