Jim Nasby wrote: > On 11/11/14, 2:03 PM, Alvaro Herrera wrote: > >Jim Nasby wrote: > >>On 11/10/14, 7:40 AM, Alvaro Herrera wrote: > > > >>>Ah, right. So AFAIK we don't need to keep anything older than > >>>RecentXmin or something like that -- which is not too old. If I recall > >>>correctly Josh Berkus was saying in a thread about pg_multixact that it > >>>used about 128kB or so in <= 9.2 for his customers; that one was also > >>>limited to RecentXmin AFAIR. I think a similar volume of commit_ts data > >>>would be pretty acceptable. Moreso considering that it's turned off by > >>>default. > >> > >>FWIW, AFAICS MultiXacts are only truncated after a (auto)vacuum process is > >>able to advance datminmxid, which will (now) only happen when an entire > >>relation has been scanned (which should be infrequent). > >> > >>I believe the low normal space usage is just an indication that most > >>databases don't use many MultiXacts. > > > >That's in 9.3. Prior to that, they were truncated much more often. > > Well, we're talking about a new feature, so I wasn't looking in back > branches. ;P
Well, I did mention <= 9.2 in the text above ... -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
