On Tue, Aug 11, 2009 at 5:23 PM, Josh Berkus<josh@xxxxxxxxxxxx> wrote: > On 8/11/09 2:14 PM, Josh Berkus wrote: >> All, >> >> I've just been tweaking some autovac settings for a large database, and >> came to wonder: why does vacuum_max_freeze_age default to such a high >> number? What's the logic behind that? >> >> AFAIK, you want max_freeze_age to be the largest possible interval of >> XIDs where an existing transaction might still be in scope, but no >> larger. Yes? >> >> If that's the case, I'd assert that users who do actually go through >> 100M XIDs within a transaction window are probably doing some >> hand-tuning. And we could lower the default for most users >> considerably, such as to 1 million. > > (replying to myself) actually, we don't want to set FrozenXID until the > row is not likely to be modified again. However, for most small-scale > installations (ones where the user has not done any tuning) that's still > likely to be less than 100m transactions. I don't think that's the name of the parameter, since a Google search gives zero hits. There are so many fiddly parameters for this thing that I don't want to speculate about which one you meant. ...Robert -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
