Re: MultiXact truncation, startup et al.

On Wed, Nov 27, 2013 at 5:42 PM, Andres Freund <andres(at)2ndquadrant(dot)com> wrote:
> So, I've done this for 9.3+ for now. Testing around that turned up that
> our current way to schedule anti mxid wraparounds doesn't really work:
> 1) autovacuum.c knows about such vacuums, but vacuum.c doesn't. Leading
> to a long cycle of partial vacuums that don't increase relminmxid.
> 2) Parts of the code used 200mio as a hardcoded constant, others used
> autovacuum_freeze_max_age.
>
> 0001 fixes the vacuum scheduling and is applicable to 9.3+,

multiTableLimit is a bad name for whatever concept this is supposed to
represent. It does not involve multiple tables.
vacuum_set_xid_limits now has multiXactCutoff, multiTableLimit, and
mxLimit, and there's no explanation of what the are.

> 0002 re-adds pg_multixact truncation during crash recovery. The current
> code will only work on 9.3+, but if it's deemed acceptable I can
> backport it to earlier versions. I am not sure if it's worth backporting
> it 9.0 given it has neither HS nor SR?

Huh?

--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company