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Get the min/max optimization working with descending indices. Ticket #2514. (CVS 4161)

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FossilOrigin-Name: a80a3c9d0a5e0a8a3d67bd841e2076893fd5e9aa
This commit is contained in:
drh
2007-07-18 18:17:11 +00:00
parent e927818455
commit 309be02483
4 changed files with 406 additions and 8 deletions
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12
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 1.353 2007/06/26 10:38:55 danielk1977 Exp $
** $Id: select.c,v 1.354 2007/07/18 18:17:12 drh Exp $
*/
#include "sqliteInt.h"
@@ -2514,6 +2514,16 @@ static int simpleMinMaxQuery(Parse *pParse, Select *p, int eDest, int iParm){
sqlite3VdbeAddOp(v, OP_MakeRecord, 1, 0);
seekOp = OP_MoveGt;
}
if( pIdx->aSortOrder[0]==SQLITE_SO_DESC ){
/* Ticket #2514: invert the seek operator if we are using
** a descending index. */
if( seekOp==OP_Last ){
seekOp = OP_Rewind;
}else{
assert( seekOp==OP_MoveGt );
seekOp = OP_MoveLt;
}
}
sqlite3VdbeAddOp(v, seekOp, iIdx, 0);
sqlite3VdbeAddOp(v, OP_IdxRowid, iIdx, 0);
sqlite3VdbeAddOp(v, OP_Close, iIdx, 0);