From: Tom Lane <tgl@sss.pgh.pa.us>
To: Andres Freund <andres@2ndquadrant.com>
cc: Bruce Momjian <bruce@momjian.us>,
 Alvaro Herrera <alvherre@2ndquadrant.com>,
 PostgreSQL Bugs <pgsql-bugs@postgresql.org>
Subject: Re: pg_upgrade < 9.3 -> >=9.3 misses a step around multixacts
In-reply-to: <20140721161222.GA17049@alap3.anarazel.de>
References: <20140720223010.GF5974@alap3.anarazel.de>
 <17935.1405895946@sss.pgh.pa.us> <20140720225653.GG5974@alap3.anarazel.de>
 <18673.1405897470@sss.pgh.pa.us> <18851.1405897900@sss.pgh.pa.us>
 <20140720233125.GI5974@alap3.anarazel.de> <19458.1405899435@sss.pgh.pa.us>
 <20140720234925.GJ5974@alap3.anarazel.de> <22178.1405903964@sss.pgh.pa.us>
 <26504.1405912770@sss.pgh.pa.us> <20140721161222.GA17049@alap3.anarazel.de>
Comments: In-reply-to Andres Freund <andres@2ndquadrant.com>
 message dated "Mon, 21 Jul 2014 18:12:22 +0200"
Date: Mon, 21 Jul 2014 12:20:56 -0400
Message-ID: <3655.1405959656@sss.pgh.pa.us>
Precedence: bulk
Sender: pgsql-bugs-owner@postgresql.org

Andres Freund <andres@2ndquadrant.com> writes:
> 1) How about adding a elog(WARNING, "relation %u has invalid freeze
> limits", ...)  to vac_update_datfrozenxid()? Otherwise it's a bit hard
> to understand what's going on. I wouldn't want to invest too much effort
> into the precision of the message, but some log bleat seems justified.

I considered that but wasn't really convinced it was a good idea.
You'd be getting a lot of log spam on a 9.3 installation that had
been affected by the pg_upgrade bug, until all the tables got cleaned
up (and we're intentionally not forcing that to happen quickly).

Anybody else have an opinion?

> 2) From a pedantic POV lastSane* should be initialized to
> ReadNewTransactionId()/ReadNextMultiXactId(). On a busy system we could
> otherwise consider concurrently updated values as being too new if some
> longrunning transaction finishes. Also GetOldestXmin() can sometimes go
> backwards...

If it's wrong then that's a pre-existing bug, but I don't think it's
wrong.

			regards, tom lane


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