On Tue, Sep 6, 2016 at 2:16 PM, Simon Riggs <simon@2ndquadrant.com> wrote:
> What occurs to me is that we can exactly predict how many tuples we
> are going to get when we autovacuum, since we measure that and we know
> what the number is when we trigger it.
>
> So there doesn't need to be any guessing going on at all, nor do we
> need it to be flexible.
No, that's not really true. A lot can change between the time it's
triggered and the time it happens, or even while it's happening.
Somebody can run a gigantic bulk delete just after we start the
VACUUM.
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company