Adrian Moisey wrote: > Hi > >>>> If I tail the logs, I see a steady stream of functions that took longer >>>> then 5 seconds. But every now and then I see nothing for 3 minutes and >>>> after that a whole bunch (about 20 - 30) queries all finishing at the >>>> same second. >>> >>> Search this list for references to "checkpoints". If you run >>> vmstat/iostat for a bit you should see bursts of disk activity at those >>> times. >>> >>> Counter-intuitively you probably want *more* checkpoints (with less data >>> to write out each time), but see the list archives for discussion. Also >>> check the manuals for some background info. >> >> We use a lot of checkpoints in our database, we don't care about these > > We use a lot of temporary tables in our database, sorry. > >> much. We think this is causing the checkpoint to write a lot of data at >> checkpoint time. Can we stop this behavior ? No, data written in temp tables do not cause extra I/O on checkpoint. Catalog changes due to temp table creation could, but I doubt that's the problem. Perhaps, if you want to avoid I/O caused by temp tables (but it's not at checkpoint time, so perhaps this has nothing to do with your problem), you could try raising temp_buffers. -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support ---------------------------(end of broadcast)--------------------------- TIP 6: explain analyze is your friend
