On 2015-06-08 15:15:04 +0200, Andres Freund wrote:
> 1) the autovacuum trigger logic isn't perfect yet. I.e. especially with
> autovacuum=off you can get into situations where emergency vacuums
> aren't started when necessary. This is particularly likely to happen
> if either very large multixacts are used, or if the server has been
> shut down while emergency autovacuum where happening. No corruption
> ensues, but it's not easy to get out of.
A first version to address this problem can be found appended to this
email.
Basically it does:
* Whenever more than MULTIXACT_MEMBER_SAFE_THRESHOLD are used, signal
autovacuum once per members segment
* For both members and offsets, once hitting the hard limits, signal
autovacuum everytime. Otherwise we loose the information when
restarting the database, or when autovac is killed. I ran into this a
bunch of times while testing.
Regards,
Andres
