On 2016-01-12 17:50:36 +0530, Amit Kapila wrote: > On Tue, Jan 12, 2016 at 12:57 AM, Andres Freund <and...@anarazel.de> wrote:> > > > > My theory is that this happens due to the sorting: pgbench is an update > > heavy workload, the first few pages are always going to be used if > > there's free space as freespacemap.c essentially prefers those. Due to > > the sorting all a relation's early pages are going to be in "in a row". > > > > Not sure, what is best way to tackle this problem, but I think one way could > be to perform sorting at flush requests level rather than before writing > to OS buffers.
I'm not following. If you just sort a couple hundred more or less random buffers - which is what you get if you look in buf_id order through shared_buffers - the likelihood of actually finding neighbouring writes is pretty low. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
