Re: Why is vacuum_freeze_min_age 100m?

On Tue, Aug 11, 2009 at 6:06 PM, Josh Berkus<josh(at)agliodbs(dot)com> wrote:
>
>> 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.
>
> Sorry, subject line had it correct.
>
> http://www.postgresql.org/docs/8.4/static/runtime-config-client.html#GUC-VACUUM-FREEZE-MIN-AGE

Ah. Yeah, I agree with Tom: how would it help to make this smaller?
It seems like that could possibly increase I/O, if the old data is
changing at all, but even if it doesn't it I don't see that it saves
you anything to freeze it sooner. Generally freezing is unnecessary
pain: if we had 128-bit transaction IDs, I'm guessing that we wouldn't
care about freezing or wraparound at all. (Of course that would
create other problems, which is why we don't, but the point is
freezing is at best a necessary evil.)

...Robert