Re: [dspam-users] Postgres vs. MySQL
Lionel Bouton <lionel-subscription@bouton.name>
From: Lionel Bouton <lionel-subscription@bouton.name>
To: Casey Allen Shobe <cshobe@osss.net>
Cc: Clifton Royston <cliftonr@tikitechnologies.com>, Evilio del Rio <edelrio@cmima.csic.es>, dspam-users@networkdweebs.com, pgsql-performance@postgresql.org
Date: 2004-11-27T10:14:30Z
Lists: pgsql-performance
Casey Allen Shobe wrote the following on 11/27/04 03:11 : >I posted about this a couple days ago on dspam-dev... > >I am using DSpam with PostgreSQL, and like you discovered the horrible >performance. The reason is because the default PostgreSQL query planner >settings determine that a sequence scan will be more efficient than an >index scan, which is wrong. To correct this behavior, adjust the query >planner settings for the appropriate table/column with this command: > >alter table "dspam_token_data" alter "token" set statistics 200; analyze; > >Let me know if it help you. It worked wonders for me. > > > In tum mode, this could help too (I'm currently testing it) : CREATE INDEX id_token_data_sumhits ON dspam_token_data ((spam_hits + innocent_hits)); Indeed each UPDATE on dspam_token_data in TUM is done with : WHERE ... AND spam_hits + innocent_hits < 50