On Thu, Sep 5, 2013 at 5:11 PM, Josh Berkus <j...@agliodbs.com> wrote: > On 09/05/2013 02:16 PM, Bruce Momjian wrote: >>> Well, the real problem with this patch is that it documents what the >>> auto-tuning algorithm is; without that commitment, just saying "-1 means >>> autotune" might be fine. >> >> OK, but I did this based on wal_buffers, which has a -1 default, calls >> it auto-tuning, and explains how the default is computed. > > I don't see a real problem with this. For users who have set their > shared_buffers correctly, effective_cache_size should also be correct.
Agreed. I think -1 is the right setting for autotune as things stand today. If we want something else, then we should change other settings as well (like wal_buffers) and that is not in the scope of this patch. >> The problem there is that many users are told to tune shared_buffers, >> but don't touch effective cache size. Having initdb set the >> effective_cache_size value would not help there. Again, this is all >> based on the auto-tuning of wal_buffers. > > Standard advice we've given in the past is 25% shared buffers, 75% > effective_cache_size. Which would make EFS *3X* shared_buffers, not 4X. > Maybe we're changing the conventional calculation, but I thought I'd > point that out. This was debated upthread. merlin -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
