Excerpts from Simon Riggs's message of jue ene 19 16:05:36 -0300 2012: > On Sun, Jan 15, 2012 at 9:17 PM, Heikki Linnakangas > <heikki.linnakan...@enterprisedb.com> wrote: > > > I think it makes more sense to use the max read rate as the main knob, > > rather than write rate. That's because the max read rate is higher than the > > write rate, when you don't need to dirty pages. Or do you think saturating > > the I/O system with writes is so much bigger a problem than read I/O that it > > makes more sense to emphasize the writes? > > Yes, the writes are more important of the two. > > Too many writes at one time can overflow hardware caches, so things > tend to get much worse beyond a certain point. > > Also, rate limiting writes means we rate limit WAL rate also which is > very important. > > I'd like this to apply to large DDL, not just VACUUMs.
More generally, this can sometimes be useful in general queries as well. -- Álvaro Herrera <alvhe...@commandprompt.com> The PostgreSQL Company - Command Prompt, Inc. PostgreSQL Replication, Consulting, Custom Development, 24x7 support -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
