2010/2/25 Devrim GÜNDÜZ <devrim@xxxxxxxxxx>: > On Thu, 2010-02-25 at 22:12 -0800, Tory M Blue wrote: >> shared_buffers = 1500MB > > Some people tend to increase this to 2.2GB(32-bit) or 4-6 GB (64 bit), > if needed. Please note that more shared_buffers will lead to more > pressure on bgwriter, but it also has lots of benefits, too. > >> work_mem = 100MB > > This is too much. Since you have 300 connections, you will probably swap > because of this setting, since each connection may use this much > work_mem. The rule of the thumb is to set this to a lower general value > (say, 1-2 MB), and set it per-query when needed. > >> checkpoint_segments = 100 >> checkpoint_warning = 3600s > > What about checkpoint_timeout? Please note that even if > checkpoint_segments = 100, if timeout value is low (say 5 mins), > PostgreSQL will probably checkpoint every checkpoint_timeout minutes > (unless PostgreSQL creates $checkpoint_segments xlogs before > checkpoint_timeout value). Depending on your workload, this may not be > intended, and it may cause spikes -- which will lead to the issues you > complain. > > I'll stop here, and suggest you read this: > > http://www.westnet.com/~gsmith/content/postgresql/chkp-bgw-83.htm > > for details about this subject. As noted there, if you are running 8.3+, > pg_stat_bgwriter will help you to tune checkpoint & bgwriter settings. > > -HTH. Checkpoint_timeout is the default and that looks like 5 mins (300 seconds). And is obviously why I have such a discrepancy between time reached and requested. Thank you sir, that's actually the page that I've spent much of my time on this eve :) I'll continue to read and check my configuration settings. Tory -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
