From: | Matthew Nuzum <mattnuzum(at)gmail(dot)com> |
---|---|
To: | Csaba Nagy <nagy(at)ecircle-ag(dot)com> |
Cc: | pgsql-performance(at)postgresql(dot)org |
Subject: | Re: Help tuning postgres |
Date: | 2005-10-12 16:39:50 |
Message-ID: | f3c0b4080510120939x6c08feebvfad37c98df306538@mail.gmail.com |
Views: | Raw Message | Whole Thread | Download mbox | Resend email |
Thread: | |
Lists: | pgsql-performance |
On 10/12/05, Csaba Nagy <nagy(at)ecircle-ag(dot)com> wrote:
> We have adapted our application (originally written for oracle) to
> postgres, and switched part of our business to a postgres data base.
> The data base has in the main tables around 150 million rows, the whole
> data set takes ~ 30G after the initial migration. After ~ a month of
> usage that bloated to ~ 100G. We installed autovacuum after ~ 2 weeks.
>
> The main table is heavily updated during the active periods of usage,
> which is coming in bursts.
>
> Now Oracle on the same hardware has no problems handling it (the load),
> but postgres comes to a crawl. Examining the pg_stats_activity table I
> see the updates on the main table as being the biggest problem, they are
> very slow. The table has a few indexes on it, I wonder if they are
> updated too on an update ? The index fields are not changing. In any
> case, I can't explain why the updates are so much slower on postgres.
I'm not the most experience person on this list, but I've got some big
tables I work with. Doing an update on these big tables often involves
a sequential scan which can be quite slow.
I would suggest posting the explain analyze output for one of your
slow updates. I'll bet it is much more revealing and takes out a lot
of the guesswork.
--
Matthew Nuzum
www.bearfruit.org
From | Date | Subject | |
---|---|---|---|
Next Message | Csaba Nagy | 2005-10-12 16:55:30 | Re: Help tuning postgres |
Previous Message | Merlin Moncure | 2005-10-12 15:54:17 | Re: Help tuning postgres |