On Fri, Dec 12, 2014 at 11:12 AM, Andres Freund <and...@anarazel.de> wrote: > On 2014-12-12 11:08:52 -0500, Robert Haas wrote: >> Unless I'm missing something, this test is showing that FPW >> compression saves 298MB of WAL for 17.3 seconds of CPU time, as >> against master. And compressing the whole record saves a further 1MB >> of WAL for a further 13.39 seconds of CPU time. That makes >> compressing the whole record sound like a pretty terrible idea - even >> if you get more benefit by reducing the lower boundary, you're still >> burning a ton of extra CPU time for almost no gain on the larger >> records. Ouch! > > Well, that test pretty much doesn't have any large records besides FPWs > afaics. So it's unsurprising that it's not beneficial.
"Not beneficial" is rather an understatement. It's actively harmful, and not by a small margin. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
