Robert Haas wrote: > On Sun, Nov 9, 2014 at 8:41 PM, Alvaro Herrera <alvhe...@2ndquadrant.com> > wrote: > > Robert Haas wrote: > >> I think the key question here is the time for which the data needs to > >> be retained. 2^32 of anything is a lot, but why keep around that > >> number of records rather than more (after all, we have epochs to > >> distinguish one use of a given txid from another) or fewer? > > > > The problem is not how much data we retain; is about how much data we > > can address. > > I thought I was responding to a concern about disk space utilization.
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. -- 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
