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Re: Indexing dead tuples

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Simon Riggs <simon(at)2ndquadrant(dot)com>
Cc: pgsql-hackers(at)postgresql(dot)org
Subject: Re: Indexing dead tuples
Date: 2005-08-31 23:06:25
Message-ID: 5483.1125529585@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-hackers
Andrew - Supernews <andrew+nonews(at)supernews(dot)com> writes:
> On 2005-08-31, Simon Riggs <simon(at)2ndquadrant(dot)com> wrote:
>> During CREATE INDEX we include all tuples, even if they are already dead
>> when we build an index.
>> 
>> What purpose does this serve?
>> 
>> A pre-existing transaction can't see the index,

> Yes, it can; the catalog is read in SnapshotNow rather than in the query
> snapshot.

In fact, it had better be able to, since once the CREATE INDEX commits,
pre-existing xacts are responsible to insert index entries for anything
they insert into the table.

			regards, tom lane

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