On Tue, Oct 26, 2010 at 2:13 PM, Heikki Linnakangas <heikki.linnakan...@enterprisedb.com> wrote: > On 26.10.2010 21:03, fazool mein wrote: >>> >>> Might I suggest adopting the same technique walsender does, ie just read >>> the data back from disk? There's a reason why we gave up trying to have >>> walsender read directly from the buffers. >>> >> That is exactly what I do not want to do, i.e. read from disk, as long as >> the piece of WAL is available in the buffers. > > Why not? If the reason is performance, I'd like to see some performance > numbers to show that it's worth the trouble. You could perhaps do a quick > and dirty hack that doesn't do the locking 100% correctly first, and do some > benchmarking on that to get a ballpark number of how much potential there > is. Or run oprofile on the current walsender implementation to see how much > time is currently spent reading WAL from the kernel buffers. > >> Can you please describe why >> walsender reading directly from the buffers was given up? To avoid a lot >> of >> locking? > > To avoid locking yes, and complexity in general.
And the fact that it might allow the standby to get ahead of the master, leading to silent database corruption. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
