> That would explain all the writes, but it doesn't seem to explain why > your two servers aren't behaving similarly.
Well, that's why I said "ostensibly identical". There may in fact be differences, not just in the databases but in some OS libs as well. These servers have been in production for quite a while, and the owner has a messy deployment process. > Most likely that's the libc implementation of the select()-based sleeps > for vacuum_cost_delay. I'm still suspicious that the writes are eating > more cost_delay points than you think. Tested that. It does look like if I increase vacuum_cost_limit to 10000 and lower vacuum_cost_page_dirty to 10, it reads 5-7 pages and writes 2-3 before each pollsys. The math seems completely wrong on that, though -- it should be 50 and 30 pages, or similar. If I can, I'll test a vacuum without cost_delay and make sure the pollsys() are connected to the cost delay and not something else. -- -- Josh Berkus PostgreSQL Experts Inc. http://www.pgexperts.com -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers