Re: Postgres-7.0.2 optimization question
От | Mitch Vincent |
---|---|
Тема | Re: Postgres-7.0.2 optimization question |
Дата | |
Msg-id | 00da01c03540$d510a1f0$0200000a@doot обсуждение исходный текст |
Ответ на | Postgres-7.0.2 optimization question ("Igor V. Rafienko" <igorr@ifi.uio.no>) |
Список | pgsql-general |
If you could post the queries in question along with the table structure and EXPLAIN output of the queries, I'm sure someone might be able to suggest something.. -Mitch ----- Original Message ----- From: "Alfred Perlstein" <bright@wintelcom.net> To: "Igor V. Rafienko" <igorr@ifi.uio.no> Cc: <pgsql-general@postgresql.org> Sent: Friday, October 13, 2000 10:47 AM Subject: Re: [GENERAL] Postgres-7.0.2 optimization question > * Igor V. Rafienko <igorr@ifi.uio.no> [001013 05:09] wrote: > > > > > > Hi, > > > > > > I've got a slight optimization problem with postgres and I was hoping > > someone could give me a clue as to what could be tweaked. > > > > I have a couple of tables which contain little data (around 500,000 tuples > > each), and most operations take insanely long time to complete. The > > primary keys in both tables are ints (int8, iirc). When I perform a delete > > (with a where clause on a part of a primary key), an strace shows that > > postgres reads the entire table sequentially (lseek() and read()). Since > > each table is around 200MB, things take time. > > Postgresql fails to use the index on several of our tables, an > 'EXPLAIN <query>' would probably output a lot of lines about > doing a 'sequential scan'. > > The only solution that I've been able to come across is to issue > a 'set enable_seqscan=off;' SQL statement on most of my queries > to force postgresql to use an index. > > hope this helps, > -Alfred >
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