On Sun, Mar 27, 2011 at 01:12, Simon Riggs <si...@2ndquadrant.com> wrote: >> At the same time I would >> change count_nondeletable_pages() so that it uses a forward scan direction >> (if that leads to a speedup).
+1. > Do we need that? Linux readahead works in both directions doesn't it? > Guess it wouldn't hurt too much. Yes, probably. AFAIK, RHEL 5 cannot readahead in backward scans. It might be improved in the latest kernel, but it would be safe not to rely on kernels except simple forward scans. -- Itagaki Takahiro -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
