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Create hooks to let a loadable plugin monitor (or even replace) the planner

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and/or create plans for hypothetical situations; in particular, investigate
plans that would be generated using hypothetical indexes.  This is a
heavily-rewritten version of the hooks proposed by Gurjeet Singh for his
Index Advisor project.  In this formulation, the index advisor can be
entirely a loadable module instead of requiring a significant part to be
in the core backend, and plans can be generated for hypothetical indexes
without requiring the creation and rolling-back of system catalog entries.

The index advisor patch as-submitted is not compatible with these hooks,
but it needs significant work anyway due to other 8.2-to-8.3 planner
changes.  With these hooks in the core backend, development of the advisor
can proceed as a pgfoundry project.
This commit is contained in:
Tom Lane
2007-05-25 17:54:25 +00:00
parent ce5b24abed
commit 604ffd280b
9 changed files with 168 additions and 62 deletions
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18
src/backend/executor/nodeBitmapIndexscan.c
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@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.22 2007/01/05 22:19:28 momjian Exp $
* $PostgreSQL: pgsql/src/backend/executor/nodeBitmapIndexscan.c,v 1.23 2007/05/25 17:54:25 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -198,10 +198,12 @@ ExecEndBitmapIndexScan(BitmapIndexScanState *node)
#endif
/*
* close the index relation
* close the index relation (no-op if we didn't open it)
*/
index_endscan(indexScanDesc);
index_close(indexRelationDesc, NoLock);
if (indexScanDesc)
index_endscan(indexScanDesc);
if (indexRelationDesc)
index_close(indexRelationDesc, NoLock);
}
/* ----------------------------------------------------------------
@ -256,6 +258,14 @@ ExecInitBitmapIndexScan(BitmapIndexScan *node, EState *estate, int eflags)
indexstate->ss.ss_currentRelation = NULL;
indexstate->ss.ss_currentScanDesc = NULL;
/*
* If we are just doing EXPLAIN (ie, aren't going to run the plan),
* stop here. This allows an index-advisor plugin to EXPLAIN a plan
* containing references to nonexistent indexes.
*/
if (eflags & EXEC_FLAG_EXPLAIN_ONLY)
return indexstate;
/*
* Open the index relation.
*