On Fri, Nov 11, 2005 at 08:26:41PM +0100, Marcin Giedz wrote: > Tom Lane napisa?(a): > > >Marcin Giedz <marcin.giedz@xxxxxxxxxxxxxx> writes: > > > > > >>However I still can see 'spikey' performance but not as much as before > >>changes. What can I do more to eliminate or smooth these spikes? > >> > >> > > > >The spikes are certainly caused by checkpoints. You can fool with the > >checkpoint timing via checkpoint_segments and checkpoint_timeout. > > > > > I didn't mention before but I changed checkpoint_segments to 300 but no > checkpoint_time. Disk space doesn't matter at all ... time to > recovery.... shouldn't be very long (I don't have much experiences with > this as I do online backup every day). Can anyone please tell me what > values of these two parametres are reasonable? What Tom was refering to about 'time to recovery' is recovering from an unexpected database shutdown by replaying the WAL. If you go 5 minutes between syncing WAL to the mainline storage, then a worst-case recovery will take ~5 minutes (well, it could probably take longer, but it should be a linear relationship). The longer you make checkpoint interval, the longer you'll have to wait for the database to come back. -- Jim C. Nasby, Sr. Engineering Consultant jnasby@xxxxxxxxxxxxx Pervasive Software http://pervasive.com work: 512-231-6117 vcard: http://jim.nasby.net/pervasive.vcf cell: 512-569-9461 ---------------------------(end of broadcast)--------------------------- TIP 3: Have you checked our extensive FAQ? http://www.postgresql.org/docs/faq
