From: Alvaro Herrera <alvherre@2ndquadrant.com>
To: Arseny Sher <a.sher@postgrespro.ru>
Cc: Tom Lane <tgl@sss.pgh.pa.us>
Cc: pgsql-hackers@lists.postgresql.org
Subject: Re: pgsql: Fix "base" snapshot handling in logical decoding
Date: Thu, 5 Jul 2018 14:22:32 -0400
Message-ID: <20180705182232.3n7ih4kyhtwhmvod@alvherre.pgsql> (raw)
In-Reply-To: <87r2kliqja.fsf@ars-thinkpad>
Hi Arseny. I'm writing a commit message to push this test change, and I
can't explain this bit:
On 2018-Jul-02, Arseny Sher wrote:
> 3) As a side note, answer to my question 'why do we get different errors
> with VACUUM and VACUUM FULL' is the following. With VACUUM FULL, not
> only old pg_attribute entry is pruned, but also xmin of new entry
> with attisdropped=true is reset to frozen xid. This means that
> decoding session (RelationBuildTupleDesc) actually sees 3 attributes,
> and the fact that one of them is dropped doesn't embarrass this
> function (apparently relnatts in pg_class is never decremented) --
> we just go ahead and decode only live attributes.
I just don't see it that VACUUM FULL would change the xmin of anything
to FrozenXid, and in my experiments it doesn't. Did you mean VACUUM
FREEZE?
PS - sorry about the broken CC I added :-(
--
Álvaro Herrera https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
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To: pgsql-committers@postgresql.org
Cc: alvherre@2ndquadrant.com, a.sher@postgrespro.ru, tgl@sss.pgh.pa.us, pgsql-hackers@lists.postgresql.org
Subject: Re: pgsql: Fix "base" snapshot handling in logical decoding
In-Reply-To: <20180705182232.3n7ih4kyhtwhmvod@alvherre.pgsql>
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