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Allow GIN's extractQuery method to signal that nothing can satisfy the query.

In this case extractQuery should returns -1 as nentries. This changes
prototype of extractQuery method to use int32* instead of uint32* for
nentries argument.
Based on that gincostestimate may see two corner cases: nothing will be found
or seqscan should be used.

Per proposal at http://archives.postgresql.org/pgsql-hackers/2007-01/msg01581.php

PS tsearch_core patch should be sightly modified to support changes, but I'm
waiting a verdict about reviewing of tsearch_core patch.
This commit is contained in:
Teodor Sigaev
2007-01-31 15:09:45 +00:00
parent 147a3ce149
commit d4c6da1527
11 changed files with 199 additions and 29 deletions

View File

@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gin/ginget.c,v 1.5 2007/01/05 22:19:21 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/gin/ginget.c,v 1.6 2007/01/31 15:09:45 teodor Exp $
*-------------------------------------------------------------------------
*/
@ -420,6 +420,7 @@ scanGetItem(IndexScanDesc scan, ItemPointerData *item)
}
#define GinIsNewKey(s) ( ((GinScanOpaque) scan->opaque)->keys == NULL )
#define GinIsVoidRes(s) ( ((GinScanOpaque) scan->opaque)->isVoidRes == true )
Datum
gingetmulti(PG_FUNCTION_ARGS)
@ -432,10 +433,13 @@ gingetmulti(PG_FUNCTION_ARGS)
if (GinIsNewKey(scan))
newScanKey(scan);
startScan(scan);
*returned_tids = 0;
if (GinIsVoidRes(scan))
PG_RETURN_BOOL(false);
startScan(scan);
do
{
if (scanGetItem(scan, tids + *returned_tids))
@ -462,6 +466,9 @@ gingettuple(PG_FUNCTION_ARGS)
if (GinIsNewKey(scan))
newScanKey(scan);
if (GinIsVoidRes(scan))
PG_RETURN_BOOL(false);
startScan(scan);
res = scanGetItem(scan, &scan->xs_ctup.t_self);
stopScan(scan);