On Sun, May 12, 2013 at 3:46 PM, Jim Nasby <j...@nasby.net> wrote: > On 5/10/13 1:06 PM, Jeff Janes wrote: >> >> Of course the paranoid DBA could turn off restart_after_crash and do a >> manual investigation on every crash, but in that case the database would >> refuse to restart even in the case where it perfectly clear that all the >> following WAL belongs to the recycled file and not the current file. > > > Perhaps we should also allow for zeroing out WAL files before reuse (or just > disable reuse). I know there's a performance hit there, but the reuse idea > happened before we had bgWriter. Theoretically the overhead creating a new > file would always fall to bgWriter and therefore not be a big deal.
For filesystems like btrfs, re-using a WAL file is suboptimal to simply creating a new one and removing the old one when it's no longer required. Using fallocate (or posix_fallocate) (I have a patch for that!) to create a new one is - by my tests - 28 times faster than the currently-used method. -- Jon -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
