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Disable an overzealous optimization the omitted sorting on a join if the first

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table gave a unique result.  The sort can only be omitted if all tables in
the join are unique.  Ticket #1358. (CVS 2589)

FossilOrigin-Name: 4f07661279fb11a06b3ddffeda672f077c0d306a
This commit is contained in:
drh
2005-08-13 16:13:04 +00:00
parent 531fe87834
commit 8718f52624
5 changed files with 64 additions and 24 deletions
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17
src/where.c
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@@ -16,7 +16,7 @@
** so is applicable. Because this module is responsible for selecting
** indices, you might also think of this module as the "query optimizer".
**
** $Id: where.c,v 1.160 2005/08/12 22:56:09 drh Exp $
** $Id: where.c,v 1.161 2005/08/13 16:13:05 drh Exp $
*/
#include "sqliteInt.h"
@@ -719,10 +719,6 @@ or_not_possible:
** constraints. Any of these columns may be missing from the ORDER BY
** clause and the match can still be a success.
**
** If the index is UNIQUE, then the ORDER BY clause is allowed to have
** additional terms past the end of the index and the match will still
** be a success.
**
** All terms of the ORDER BY that match against the index must be either
** ASC or DESC. (Terms of the ORDER BY clause past the end of a UNIQUE
** index do not need to satisfy this constraint.) The *pbRev value is
@@ -791,10 +787,9 @@ static int isSortingIndex(
}
/* The index can be used for sorting if all terms of the ORDER BY clause
** or covered or if we ran out of index columns and the it is a UNIQUE
** index.
** are covered.
*/
if( j>=nTerm || (i>=pIdx->nColumn && pIdx->onError!=OE_None) ){
if( j>=nTerm ){
*pbRev = sortOrder==SQLITE_SO_DESC;
return 1;
}
@@ -829,14 +824,12 @@ static int sortableByRowid(
** the total cost of performing operatings with O(logN) or O(NlogN)
** complexity. Because N is just a guess, it is no great tragedy if
** logN is a little off.
**
** We can assume N>=1.0;
*/
static double estLog(double N){
double logN = 1.0;
double x = 10.0;
while( N>x ){
logN = logN+1.0;
logN += 1.0;
x *= 10;
}
return logN;
@@ -1013,7 +1006,7 @@ static double bestIndex(
*/
if( pOrderBy ){
if( (flags & WHERE_COLUMN_IN)==0 &&
isSortingIndex(pParse, pProbe, pSrc->pTab, iCur, pOrderBy, nEq, &rev) ){
isSortingIndex(pParse,pProbe,pSrc->pTab,iCur,pOrderBy,nEq,&rev) ){
if( flags==0 ){
flags = WHERE_COLUMN_RANGE;
}