Re: Auto Vacuum

Matthew T. O'Connor wrote:
> Bruce Momjian wrote:
>
> >Matthew T. O'Connor wrote:
> >
> >
> >>Bruce Momjian wrote:
> >>
> >>
> >>>I have added an auto-vacuum TODO item:
> >>>
> >>>* Auto-vacuum
> >>> o Move into the backend code
> >>> o Scan the buffer cache to find free space or use background writer
> >>> o Use free-space map information to guide refilling
> >>>
> >>>
> >>I'm not sure what you mean exactly by "Scan the buffer cache to find
> >>free space or use background writer", the other two are definitely high
> >>priority todo items (at least as far as autovacuum in concerned).
> >>
> >>
> >
> >I am thinking we could look for expired tuples when while they are in
> >the buffer cache or before they are written to disk so we don't have to
> >a sequential scan to find them.
> >
> >
>
> Is that related to autovacuum? Or is that a potential feature inside the
> actual vacuum command?

That could be part of auto-vacuum. Vacuum itself would still sequential
scan, I think. The idea is to easily grab expire tuples when they are
most cheaply found.

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