On Fri, Jan 02, 2015 at 01:01:06PM +0100, Andres Freund wrote: > On 2014-12-31 16:09:31 -0500, Bruce Momjian wrote: > > I still don't understand the value of adding WAL compression, given the > > high CPU usage and minimal performance improvement. The only big > > advantage is WAL storage, but again, why not just compress the WAL file > > when archiving. > > before: pg_xlog is 800GB > after: pg_xlog is 600GB. > > I'm damned sure that many people would be happy with that, even if the > *per backend* overhead is a bit higher. And no, compression of archives > when archiving helps *zap* with that (streaming, wal_keep_segments, > checkpoint_timeout). As discussed before. > > Greetings, > > Andres Freund >
+1 On an I/O constrained system assuming 50:50 table:WAL I/O, in the case above you can process 100GB of transaction data at the cost of a bit more CPU. Regards, Ken -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers