Re: Possible bug in vacuum redo - Mailing list pgsql-hackers

From Hiroshi Inoue
Subject Re: Possible bug in vacuum redo
Date
Msg-id 3C267F2F.99D6A78E@tpf.co.jp
Whole thread Raw
In response to Re: Possible bug in vacuum redo  ("Hiroshi Inoue" <Inoue@tpf.co.jp>)
Responses Re: Possible bug in vacuum redo  (Tom Lane <tgl@sss.pgh.pa.us>)
List pgsql-hackers
Tom Lane wrote:
> 
> Hiroshi Inoue <Inoue@tpf.co.jp> writes:
> > I don't think it's preferable either. However there's
> > no problem unless there's an application which handle
> > the tuples containing the t_ctid link.
> 
> What about READ COMMITTED mode?  EvalPlanQual uses the t_ctid field
> to find the updated version of the row.

In READ COMMITTED mode, an app searches valid tuples first
using the snapshot taken when the query started. It never
searches already updated(to newer ones) and committed tuples
at the point when the query started. Essentially t_ctid is
only needed by the concurrently running backends.

regards,
Hiroshi Inoue


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