Lonni J Friedman wrote: > After reading this interesting article on shared_buffers and wal_buffers: > http://rhaas.blogspot.com/2012/03/tuning-sharedbuffers-and-walbuffers.html > > it got me wondering if my settings were ideal. Is there some way to > measure wal_buffer usage in real time, so that I could simply monitor > it for some period of time, and then come up with a way of determining > if the current setting is sufficient? > > I tried googling, but every reference that I've found simply defaults > to the "trial & error" approach to performance tuning.
You can use the contrib module pg_buffercache to inspect the shared buffers. If almost all your shared buffers have high use count (4 or 5), shared_buffers may be too small. If not, consider reducing shared_buffers. It's probably better to start with a moderate value and tune upwards. You can also look at pg_statio_all_tables and pg_statio_all_indexes and calculate the buffer hit ratio. If that is low, that's also an indication that shared_buffers is too small. You should distinguish between tables and indexes: it is usually more important that indexes are cached. Try to observe these things over time, for example by taking snapshots every n minutes and storing the results in a table. Yours, Laurenz Albe -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
