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Don't try to run clauseless index scans on index types that don't support

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it.  Per report from Marinos Yannikos.
This commit is contained in:
Tom Lane 2005-04-20 21:48:04 +00:00
parent a8ac7d8713
commit eb4f58ad40
1 changed files with 17 additions and 7 deletions
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24
src/backend/optimizer/path/indxpath.c
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@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.173 2005/04/11 23:06:55 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.174 2005/04/20 21:48:04 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -146,11 +146,16 @@ create_index_paths(Query *root, RelOptInfo *rel)
* 2. Compute pathkeys describing index's ordering, if any, then
* see how many of them are actually useful for this query.
*/
index_pathkeys = build_index_pathkeys(root, index,
ForwardScanDirection);
index_is_ordered = (index_pathkeys != NIL);
useful_pathkeys = truncate_useless_pathkeys(root, rel,
index_pathkeys);
index_is_ordered = OidIsValid(index->ordering[0]);
if (index_is_ordered)
{
index_pathkeys = build_index_pathkeys(root, index,
ForwardScanDirection);
useful_pathkeys = truncate_useless_pathkeys(root, rel,
index_pathkeys);
}
else
useful_pathkeys = NIL;
/*
* 3. Generate an indexscan path if there are relevant restriction
@ -160,10 +165,15 @@ create_index_paths(Query *root, RelOptInfo *rel)
* If there is a predicate, consider it anyway since the index
* predicate has already been found to match the query. The
* selectivity of the predicate might alone make the index useful.
*
* Note: not all index AMs support scans with no restriction clauses.
* We assume here that the AM does so if and only if it supports
* ordered scans. (It would probably be better if there were a
* specific flag for this in pg_am, but there's not.)
*/
if (restrictclauses != NIL ||
useful_pathkeys != NIL ||
index->indpred != NIL)
(index->indpred != NIL && index_is_ordered))
add_path(rel, (Path *)
create_index_path(root, index,
restrictclauses,