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Skip opfamily check in eclass_matches_any_index() when the index isn't a

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btree.  We can't easily tell whether clauses generated from the equivalence
class could be used with such an index, so just assume that they might be.
This bit of over-optimization prevented use of non-btree indexes for nestloop
inner indexscans, in any case where the join uses an equality operator that
is also a btree operator --- which in particular is typically true for hash
indexes.  Noted while trying to test the current hash index patch.
This commit is contained in:
Tom Lane 2008-09-12 14:56:19 +00:00
parent 2d4ef572b4
commit e5b1eed7c9
1 changed files with 13 additions and 2 deletions
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15
src/backend/optimizer/path/indxpath.c
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@ -9,7 +9,7 @@
*
*
* IDENTIFICATION
* $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.227 2008/02/07 17:53:53 tgl Exp $
* $PostgreSQL: pgsql/src/backend/optimizer/path/indxpath.c,v 1.227.2.1 2008/09/12 14:56:19 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1584,7 +1584,18 @@ eclass_matches_any_index(EquivalenceClass *ec, EquivalenceMember *em,
{
Oid curFamily = families[0];
if (list_member_oid(ec->ec_opfamilies, curFamily) &&
/*
* If it's a btree index, we can reject it if its opfamily isn't
* compatible with the EC, since no clause generated from the
* EC could be used with the index. For non-btree indexes,
* we can't easily tell whether clauses generated from the EC
* could be used with the index, so only check for expression
* match. This might mean we return "true" for a useless index,
* but that will just cause some wasted planner cycles; it's
* better than ignoring useful indexes.
*/
if ((index->relam != BTREE_AM_OID ||
list_member_oid(ec->ec_opfamilies, curFamily)) &&
match_index_to_operand((Node *) em->em_expr, indexcol, index))
return true;