On Fri, Mar 4, 2011 at 6:40 AM, Mark Thornton <mthornton@xxxxxxxxxxxx> wrote: > The query plan appends sequential scans on the tables in the partition (9 > tables, ~4 million rows) and then hash joins that with a 14 row table. The > join condition is the primary key of each table in the partition (and would > be the primary key of the parent if that was supported). > It would be much faster if it did an index scan on each of the child tables > and merged the results. > > I can achieve this manually by rewriting the query as a union between > queries against each of the child tables. Is there a better way? (I'm using > PostGreSQL 8.4 with PostGIS 1.4). Can you post the EXPLAIN ANALYZE output of the other formulation of the query? > -> Seq Scan on linkids (cost=0.00..31.40 rows=2140 width=8) > (actual time=0.006..0.012 rows=14 loops=1) That seems quite surprising. There are only 14 rows in the table but PG thinks 2140? Do you have autovacuum turned on? Has this table been analyzed recently? -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
