Re: Vacuum only with 20% old tuples - Mailing list pgsql-hackers

From JanWieck@t-online.de (Jan Wieck)
Subject Re: Vacuum only with 20% old tuples
Date
Msg-id 200007121117.NAA23436@hot.jw.home
Whole thread Raw
In response to Re: Vacuum only with 20% old tuples  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:
> "Hiroshi Inoue" <Inoue@tpf.co.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
thatdon't exist any   more.
 


Jan

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