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First cut at optimizing single-row updates to use a one-pass algorithm. (CVS 4973)

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FossilOrigin-Name: fba97f7874d723111e873d1470fc1a95e64f922d
This commit is contained in:
drh
2008-04-10 13:33:18 +00:00
parent 67ade0a2d0
commit 08c88eb0d3
7 changed files with 68 additions and 40 deletions
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20
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 1.425 2008/04/01 05:07:15 drh Exp $
** $Id: select.c,v 1.426 2008/04/10 13:33:18 drh Exp $
*/
#include "sqliteInt.h"
@@ -2677,7 +2677,7 @@ static int flattenSubquery(
/*
** Analyze the SELECT statement passed as an argument to see if it
** is a min() or max() query. Return ORDERBY_MIN or ORDERBY_MAX if
** is a min() or max() query. Return WHERE_ORDERBY_MIN or WHERE_ORDERBY_MAX if
** it is, or 0 otherwise. At present, a query is considered to be
** a min()/max() query if:
**
@@ -2690,18 +2690,18 @@ static int minMaxQuery(Parse *pParse, Select *p){
Expr *pExpr;
ExprList *pEList = p->pEList;
if( pEList->nExpr!=1 ) return ORDERBY_NORMAL;
if( pEList->nExpr!=1 ) return WHERE_ORDERBY_NORMAL;
pExpr = pEList->a[0].pExpr;
pEList = pExpr->pList;
if( pExpr->op!=TK_AGG_FUNCTION || pEList==0 || pEList->nExpr!=1 ) return 0;
if( pEList->a[0].pExpr->op!=TK_AGG_COLUMN ) return ORDERBY_NORMAL;
if( pExpr->token.n!=3 ) return ORDERBY_NORMAL;
if( pEList->a[0].pExpr->op!=TK_AGG_COLUMN ) return WHERE_ORDERBY_NORMAL;
if( pExpr->token.n!=3 ) return WHERE_ORDERBY_NORMAL;
if( sqlite3StrNICmp((char*)pExpr->token.z,"min",3)==0 ){
return ORDERBY_MIN;
return WHERE_ORDERBY_MIN;
}else if( sqlite3StrNICmp((char*)pExpr->token.z,"max",3)==0 ){
return ORDERBY_MAX;
return WHERE_ORDERBY_MAX;
}
return ORDERBY_NORMAL;
return WHERE_ORDERBY_NORMAL;
}
/*
@@ -3559,7 +3559,7 @@ int sqlite3Select(
if( flag ){
pDel = pMinMax = sqlite3ExprListDup(db, p->pEList->a[0].pExpr->pList);
if( pMinMax && !db->mallocFailed ){
pMinMax->a[0].sortOrder = ((flag==ORDERBY_MIN)?0:1);
pMinMax->a[0].sortOrder = ((flag==WHERE_ORDERBY_MIN)?0:1);
pMinMax->a[0].pExpr->op = TK_COLUMN;
}
}
@@ -3577,7 +3577,7 @@ int sqlite3Select(
updateAccumulator(pParse, &sAggInfo);
if( !pMinMax && flag ){
sqlite3VdbeAddOp2(v, OP_Goto, 0, pWInfo->iBreak);
VdbeComment((v, "%s() by index", (flag==ORDERBY_MIN?"min":"max")));
VdbeComment((v, "%s() by index", (flag==WHERE_ORDERBY_MIN?"min":"max")));
}
sqlite3WhereEnd(pWInfo);
finalizeAggFunctions(pParse, &sAggInfo);