Re: truncating pg_multixact/members

On Mon, Jan 6, 2014 at 7:50 PM, Jim Nasby <jim(at)nasby(dot)net> wrote:
> On 1/4/14, 8:19 AM, Robert Haas wrote:
>> Also, while multixactid_freeze_min_age should be low, perhaps a
>> million as you suggest, multixactid_freeze_table_age should NOT be
>> lowered to 3 million or anything like it. If you do that, people who
>> are actually doing lots of row locking will start getting many more
>> full-table scans. We want to avoid that at all cost. I'd probably
>> make the default the same as for vacuum_freeze_table_age, so that
>> mxids only cause extra full-table scans if they're being used more
>> quickly than xids.
>
> Same default as vacuum_freeze_table_age, or default TO
> vacuum_freeze_table_age? I'm thinking the latter makes more sense...

Same default. I think it's a mistake to keep leading people to think
that the sensible values for one set of parameters are somehow related
to a sensible set of values for the other set. They're really quite
different things.

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