Re: BUG #17717: Regression in vacuumdb (15 is slower than 10/11 and possible memory issue)

On Thu, Dec 15, 2022 at 08:39:54PM -0800, Peter Geoghegan wrote:
> On Thu, Dec 15, 2022 at 1:57 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> I could get behind manual VACUUM not invoking vac_update_datfrozenxid
>> by default, perhaps. But if it can never call it, then that is a
>> fairly important bit of housekeeping that is unreachable except by
>> autovacuum. No doubt the people who turn off autovacuum are benighted,
>> but they're still out there.
>
> I wouldn't mind adding another option for this to VACUUM. We already
> have a couple of VACUUM options that are only really needed as escape
> hatches, or perhaps as testing tools used by individual Postgres
> hackers. Another one doesn't seem too bad. The VACUUM command should
> eventually become totally niche, so I'm not too concerned about going
> overboard here.

Perhaps there could also be an update-datfrozenxid function that vacuumdb
calls when finished with a database. Even if vacuum becomes smarter about
calling vac_update_datfrozenxid, this might still be worth doing.

--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com