On 5 Březen 2012, 16:11, Marc Schablewski wrote: > We have an optimizer problem regarding partitioned tables on 8.4.11. ... > gdw=> explain select min( emg_id ) from edifactmsgpart; > QUERY PLAN > -------------------------------------------------------------------------------------------------------------- > Aggregate (cost=23521692.03..23521692.04 rows=1 width=8) > -> Append (cost=0.00..20944139.42 rows=1031021042 width=8) > -> Seq Scan on edifactmsgpart (cost=0.00..13.70 rows=370 > width=8) > -> Seq Scan on edifactmsgpart_pact edifactmsgpart > (cost=0.00..20944125.72 rows=1031020672 > width=8) > > I would expect this to run half an hour or so, completely overloading the > server... > > Any Ideas? This is a well known "feature" of pre-9.1 releases - it simply does not handle min/max on partitioned tables well. There's even an example of a workaround on the wiki: https://wiki.postgresql.org/wiki/Efficient_min/max_over_partitioned_table Another option is to upgrade to 9.1 which handles this fine. Tomas -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
