On Thu, Feb 18, 2010 at 7:04 PM, Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> wrote: > Magnus Hagander wrote: >> O_DIRECT helps us when we're not going to read the file again, because >> we don't waste cache on it. If we are, which is the case here, it >> should be really bad for performance, since we actually have to do a >> physical read. >> >> Incidentally, that should also apply to general WAL when archive_mdoe >> is on. Do we optimize for that? > > Hmm, no we don't. We do take that into account so that we refrain from > issuing posix_fadvice(DONTNEED) if archive_mode is on, but we don't > disable O_DIRECT. Maybe we should..
Since the performance of WAL write is more important than that of WAL archiving in general, that optimization might offer little benefit. Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
