Claudio Freire wrote:
> On Thu, Jul 27, 2017 at 1:46 PM, Alvaro Herrera
> <> wrote:
> > Claudio Freire wrote:
> >
> >> > The vacuuming the very large table with no index could also take a
> >> > long time, and it scans and vacuums blocks one by one. So I imagined
> >> > that we can vacuum the FSM once vacuumed a certain amount of blocks.
> >> > And that can avoid bloating table during the long-time vacuum.
> >>
> >> Could do that. I'll see about doing something of the sort and
> >> submitting it as a separate patch.
> >
> > Vacuuming of the FSM is in no way strictly tied to vacuuming the heap
> > (it's not really "vacuuming", it's just about updating the upper layers
> > to match the data in the leaves).  I think we could use the new autovac
> > "workitem" infrastructure and tack an item there once in a while for FSM
> > vacuuming ...
> Well, it *is* tied in the sense that vacuum is the one massively
> adding free space.

Yes, but if vacuum dies after releasing lots of space but before
vacuuming FSM, then it's not tied anymore and you could just as well run
it anytime.

Álvaro Herrera      
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

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