Re: Vacuum only with 20% old tuples

Tom Lane wrote:
> "Hiroshi Inoue" <Inoue(at)tpf(dot)co(dot)jp> writes:
> >> We can't "drop and recreate" without a solution to the relation
> >> versioning issue (unless you are prepared to accept a nonfunctional
> >> database after a failure partway through index rebuild on a system
> >> table). I think we should do this, but it's not all that simple...
>
> > Is this topic independent of WAL in the first place ?
>
> Sure, unless Vadim sees some clever way of using WAL to eliminate
> the need for versioned relations. But as far as I've seen in the
> discussions, versioned relations are independent of WAL.
>
> Basically what I want here is to build the new index relation as
> a new file (set of files, if large) and then atomically commit it
> as the new version of the index.

What implicitly says we need to vacuum the toast relation
AFTER beeing completely done with the indices - in contranst
to what you said before. Otherwise, the old index (the
active one) would still refer to entries that don't exist any
more.

Jan

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