On Fri, Jan 2, 2015 at 05:55:52PM +0100, Andres Freund wrote: > On 2015-01-02 11:52:42 -0500, Bruce Momjian wrote: > > Why are we not seeing the 33% compression and 15% performance > > improvement he saw? What am I missing here? > > To see performance improvements something needs to be the bottleneck. If > WAL writes/flushes aren't that in the tested scenario, you won't see a > performance benefit. Amdahl's law and all that. > > I don't understand your negativity about the topic.
I remember the initial post from Masao in August 2013 showing a performance boost, so I assumed, while we had the concurrent WAL insert performance improvement in 9.4, this was going to be our 9.5 WAL improvement. While the WAL insert performance improvement required no tuning and was never a negative, I now see the compression patch as something that has negatives, so has to be set by the user, and only wins in certain cases. I am disappointed, and am trying to figure out how this became such a marginal win for 9.5. :-( My negativity is not that I don't want it, but I want to understand why it isn't better than I remembered. You are basically telling me it was always a marginal win. :-( Boohoo! -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers