På mandag 09. februar 2015 kl. 22:36:55, skrev Igor Neyman < iney...@perceptron.com <mailto:iney...@perceptron.com>>:
From: pgsql-performance-ow...@postgresql.org [mailto:pgsql-performance-ow...@postgresql.org]On Behalf Of Andreas Joseph Krogh Sent: Monday, February 09, 2015 4:13 PM To: pgsql-performance@postgresql.org Subject: [PERFORM] Poor performance when deleting from entity-attribute-value type master-table Hi all. Using PG-9.4.0 I'm seeing this trying to delete from an "entity"-master table: *# explain analyze delete from onp_crm_entity where entity_id IN (select tmp.delivery_id from temp_delete_delivery_id tmp); QUERY PLAN --------------------------------------------------------------------------------------------------------------------------------------------------- Delete on onp_crm_entity (cost=0.43..5673.40 rows=1770 width=12) (actual time=7.370..7.370 rows=0 loops=1) -> Nested Loop (cost=0.43..5673.40 rows=1770 width=12) (actual time=0.050..1.374 rows=108 loops=1) -> Seq Scan on temp_delete_delivery_id tmp (cost=0.00..27.70 rows=1770 width=14) (actual time=0.014..0.080 rows=108 loops=1) -> Index Scan using onp_crm_entity_pkey on onp_crm_entity (cost=0.43..3.18 rows=1 width=14) (actual time=0.010..0.011 rows=1 loops=108) Index Cond: (entity_id = tmp.delivery_id) Planning time: 0.314 ms Trigger for constraint onp_crm_activity_entity_id_fkey: time=4.141 calls=108 Trigger for constraint ... Trigger for constraint ... Trigger for constraint ... I have lots of tables referencing onp_crm_entity(entity_id) so I expect the poor performance of deleting from it is caused by all the triggers firing to check FKI-constraints. Andreas, do you have indexes on FK columns in child tables? If not – there is your problem. Yes, they have indexes, but deleting 1M rows still results in calling the triggers 1M times * number of FKs... -- Andreas Joseph Krogh CTO / Partner - Visena AS Mobile: +47 909 56 963 andr...@visena.com <mailto:andr...@visena.com> www.visena.com <https://www.visena.com> <https://www.visena.com>
