On Tue, May 6, 2014 at 11:15:17PM +0100, Simon Riggs wrote: > > Well, for what it's worth, I've encountered systems where setting > > effective_cache_size too low resulted in bad query plans, but I've > > never encountered the reverse situation. > > I agree with that. > > Though that misses my point, which is that you can't know that all of > that memory is truly available on a server with many concurrent users. > Choosing settings that undercost memory intensive plans are not the > best choice for a default strategy in a mixed workload when cache may > be better used elsewhere, even if such settings make sense for some > individual users.
This is the same problem we had with auto-tuning work_mem, in that we didn't know what other concurrent activity was happening. Seems we need concurrent activity detection before auto-tuning work_mem and effective_cache_size. -- 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
