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. > > pg_buffercache only reports on the buffer_cache, it does not report > any data on the wal_cache.
You are right. >> 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. > > Isn't this also specific to the buffer_cache rather than the wal_cache? Correct. I don't know how to inspect usage WAL cache usage. 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
