Jonatan Evald Buus <jonatan.buus@xxxxxxxxxxxxxxxxxxx> writes: > We're currently having very poor performance for the following delete query. > DELETE FROM TopTable WHERE id IN (xx, yy, zz); > We've observed that it takes around 7 seconds under normal load to for each > row that's being from TopTable and several minutes pr deleted row under > heavy load. I'd really have to bet that you forgot to index one of the referencing tables. Are any of the foreign keys multi-column? If so you probably need a matching multi-column index, not just indexes on the individual referencing columns. > How do we track down the cause of the poorly performing delete query? EXPLAIN ANALYZE on a DELETE, for starters. That would isolate whether it's the DELETE itself or one of the foreign-key updates, and if the latter which one. It's a little bit difficult to see the exact plan being used for a foreign-key update query, but I think one way you could do it is to enable auto_explain with auto_explain.log_nested_statements turned on. 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
