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

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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
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17
src/backend/access/gin/ginscan.c
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@@ -8,7 +8,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/access/gin/ginscan.c,v 1.8 2007/01/05 22:19:21 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/gin/ginscan.c,v 1.9 2007/01/31 15:09:45 teodor Exp $
*-------------------------------------------------------------------------
*/
@@ -145,10 +145,12 @@ newScanKey(IndexScanDesc scan)
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("GIN indexes do not support whole-index scans")));
so->isVoidRes = false;
for (i = 0; i < scan->numberOfKeys; i++)
{
Datum *entryValues;
uint32 nEntryValues;
int32 nEntryValues;
if (scankey[i].sk_flags & SK_ISNULL)
elog(ERROR, "Gin doesn't support NULL as scan key");
@@ -162,6 +164,15 @@ newScanKey(IndexScanDesc scan)
UInt16GetDatum(scankey[i].sk_strategy)
)
);
if ( nEntryValues < 0 )
{
/*
* extractQueryFn signals that nothing will be found,
* so we can just set isVoidRes flag...
*/
so->isVoidRes = true;
break;
}
if (entryValues == NULL || nEntryValues == 0)
/* full scan... */
continue;
@@ -173,7 +184,7 @@ newScanKey(IndexScanDesc scan)
so->nkeys = nkeys;
if (so->nkeys == 0)
if (so->nkeys == 0 && !so->isVoidRes)
ereport(ERROR,
(errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
errmsg("GIN index does not support search with void query")));