"John L. Clark" <jlc6@xxxxxxxxxxx> writes: > I posted this earlier, but I haven't seen it come through the mailing > list, perhaps because of the attachment. I have also posted the > attachment at <http://infinitesque.net/temp/union_performance_2009-04-21.postgresql.dump.gz>. Ah. The problem is that your view contains constants in the UNION arms: CREATE VIEW uri_or_literal_object AS SELECT literalproperties.subject, literalproperties.subject_term, literalproperties.predicate, literalproperties.predicate_term, literalproperties.object, 'L'::character(1) AS object_term, literalproperties.context, literalproperties.context_term, literalproperties.data_type, literalproperties.language FROM literalproperties UNION ALL SELECT relations.subject, relations.subject_term, relations.predicate, relations.predicate_term, relations.object, relations.object_term, relations.context, relations.context_term, NULL::bigint AS data_type, NULL::character varying(3) AS language FROM relations; In 8.2 and 8.3, the planner is only smart enough to generate inner-indexscan nestloop plans on UNIONs if all the elements of the SELECT lists are simple variables (that is, table columns). 8.4 will be smarter about this. 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
