On Thu, Dec 11, 2014 at 11:34 AM, Bruce Momjian <br...@momjian.us> wrote: >> compression = 'on' : 1838 secs >> = 'off' : 1701 secs >> >> Different is around 140 secs. > > OK, so the compression took 2x the cpu and was 8% slower. The only > benefit is WAL files are 35% smaller?
Compression didn't take 2x the CPU. It increased user CPU from 354.20 s to 562.67 s over the course of the run, so it took about 60% more CPU. But I wouldn't be too discouraged by that. At least AIUI, there are quite a number of users for whom WAL volume is a serious challenge, and they might be willing to pay that price to have less of it. Also, we have talked a number of times before about incorporating Snappy or LZ4, which I'm guessing would save a fair amount of CPU -- but the decision was made to leave that out of the first version, and just use pg_lz, to keep the initial patch simple. I think that was a good decision. -- 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
