Hello, On Wed, Aug 13, 2014 at 5:28 PM, Marti Raudsepp <ma...@juffo.org> wrote:
> On Wed, Aug 13, 2014 at 9:44 AM, Albe Laurenz <laurenz.a...@wien.gv.at> > wrote: > > Set wal_buffers to 16MB so that a whole WAL segment will fit. > > No need, wal_buffers is automatically tuned now. If your > shared_buffers is 512MB or larger, wal_buffers will be 16MB. > > Thanks everyone, The settings that seem to work well for our workload/hw are shared_buffers = 2GB wal_buffers = 16MB effective_cache_size = 100GB checkpoint_segments = 32 * With shared_buffers set to default and wal_buffers set to 16MB - bgwriter stats indicates most writes were due to backend_buffers and not checkpoint buffers * With shared_buffers set to 2GB and wal_buffers set to 16MB - bgwriter stats indicates most writes were due to checkpoint_buffers and not backend buffers * Increasing wal_buffers beyond 16mb did not show any improvements I also found good advice about shared_buffers and wal_buffers on this slides : http://2ndquadrant.com/media/pdfs/talks/MonitoringBufferCache.pdf Few aspects that iam confused about are - a. what is the relation between shared_buffers and wal_buffers when wal_buffers is set manually ? b. What else is shared_buffers used for ? c. Why does increasing shared_buffers to 2GB from default while leaving wal_buffers constant at 16MB increase checkpoint buffer writes ? tia dushy
