Chris <dmagick@xxxxxxxxx> writes: > The query: > SELECT > assetid, custom_val > FROM > sq_ast_attr_val > WHERE > attrid IN (SELECT attrid FROM sq_ast_attr WHERE name = > 'is_contextable' AND (type_code = 'metadata_field_select' OR > owning_type_code = 'metadata_field')) > AND contextid = 0 > INTERSECT > SELECT > assetid, custom_val > FROM > sq_ast_attr_val > WHERE > assetid = '62321' > AND contextid = 0; > The explain analyze plan: > http://explain.depesz.com/s/nWs Hrm ... are you *certain* that's an 8.4 server? Because the bit with Index Cond: (sq_ast_attr_val.attrid = "outer".attrid) is a locution that EXPLAIN hasn't used since 8.1, according to a quick check. More recent versions don't say "outer". The actual problem seems to be that choose_bitmap_and() is choosing to add an indexscan on sq_ast_attr_val_contextid, even though this index is a lot less selective than the sq_ast_attr_val_attrid scan it had already picked. I've seen that behavior before, and there were a series of patches back in 2006-2007 that seem to have pretty much fixed it. So that's another reason for suspecting you've got an old server version there... regards, tom lane -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
