On Thu, Jun 4, 2015 at 1:27 PM, Andres Freund <andres@anarazel.de> wrote:
> On 2015-06-04 12:57:42 -0400, Robert Haas wrote:
>> + /*
>> + * Do we need an emergency autovacuum? If we're not sure, assume yes.
>> + */
>> + return !oldestOffsetKnown ||
>> + (nextOffset - oldestOffset > MULTIXACT_MEMBER_SAFE_THRESHOLD);
>
> I think without teaching autovac about those rules, this might just lead
> to lots of autovac processes starting without knowing they should do
> something? They know about autovacuum_multixact_freeze_age, but they
> know neither about !oldestOffsetKnown nor, afaics, about pending offset
> wraparounds?
You're right, but that's why the latest patch has changes in
MultiXactMemberFreezeThreshold.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
