On 10/12/05, Csaba Nagy <[EMAIL PROTECTED]> 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 ---------------------------(end of broadcast)--------------------------- TIP 5: don't forget to increase your free space map settings
