On Fri, Apr 24, 2015 at 1:31 AM, Jim Nasby <jim.na...@bluetreble.com> wrote: > On 4/23/15 11:06 AM, Petr Jelinek wrote: >> >> On 23/04/15 17:45, Bruce Momjian wrote: >>> >>> On Thu, Apr 23, 2015 at 09:45:38AM -0400, Robert Haas wrote: >>> Agreed, no extra file, and the same write volume as currently. It would >>> also match pg_clog, which uses two bits per transaction --- maybe we can >>> reuse some of that code. >>> >> >> Yeah, this approach seems promising. We probably can't reuse code from >> clog because the usage pattern is different (key for clog is xid, while >> for visibility/freeze map ctid is used). But visibility map storage >> layer is pretty simple so it should be easy to extend it for this use. > > > Actually, there may be some bit manipulation functions we could reuse; > things like efficiently counting how many things in a byte are set. Probably > doesn't make sense to fully refactor it, but at least CLOG is a good source > for cut/paste/whack. >
I agree with adding a bit that indicates corresponding page is all-frozen into VM, just like CLOG. I'll change the patch as second version patch. Regards, ------- Sawada Masahiko -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
