On Wed, Oct 10, 2012 at 2:03 PM, Bruce Momjian <bruce@xxxxxxxxxx> wrote: > On Wed, Oct 10, 2012 at 10:12:51PM +0200, Strahinja Kustudić wrote: >> @Claudio So you are basically saying that if I have set effective_cache_size to >> 10GB and I have 10 concurrent processes which are using 10 different indices >> which are for example 2GB, it would be better to set the effective_cache size >> to 1GB? Since if I leave it at 10GB each running process query planner will >> think the whole index is in cache and that won't be true? Did I get that right? > > Well, the real question is whether, while traversing the index, if some > of the pages are going to be removed from the cache by other process > cache usage. effective_cache_size is not figuring the cache will remain > between queries. Does anyone see effective_cache_size make a difference anyway? If so, in what circumstances? In my hands, queries for which effective_cache_size might come into play (for deciding between seq scan and index scan) are instead planned as bitmap scans. Cheers, Jeff -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
