On 2014-06-04 09:51:36 -0400, Robert Haas wrote: > On Wed, Jun 4, 2014 at 2:08 AM, Andres Freund <and...@2ndquadrant.com> wrote: > > On 2014-06-04 10:24:13 +0530, Amit Kapila wrote: > >> Incase of recovery, the shared buffers saved by this utility are > >> from previous shutdown which doesn't seem to be of more use > >> than buffers loaded by recovery. > > > > Why? The server might have been queried if it's a hot standby one? > > I think that's essentially the same point Amit is making. Gurjeet is > arguing for reloading the buffers from the previous shutdown at end of > recovery; IIUC, Amit, you, and I all think this isn't a good idea.
I think I am actually arguing for Gurjeet's position. If the server is actively being queried (i.e. hot_standby=on and actually used for queries) it's quite reasonable to expect that shared_buffers has lots of content that is *not* determined by WAL replay. There's not that much read IO going on during WAL replay anyway - after a crash/start from a restartpoint most of it is loaded via full page anyway. So it's only disadvantageous to fault in pages via pg_hibernate if that causes pages that already have been read in via FPIs to be thrown out. Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (email@example.com) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers