Re: Is anyone aware of data loss causing MultiXact bugs in 9.3.2?

From: Peter Geoghegan <pg(at)heroku(dot)com>
To: Alvaro Herrera <alvherre(at)2ndquadrant(dot)com>
Cc: Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: Is anyone aware of data loss causing MultiXact bugs in 9.3.2?
Date: 2014-02-19 02:10:02
Message-ID: CAM3SWZQ2vpLmzYscV32m=VY7W5qEsUUB26kvOAEcLj6RrRhLbw@mail.gmail.com
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On Tue, Feb 18, 2014 at 5:50 PM, Alvaro Herrera
<alvherre(at)2ndquadrant(dot)com> wrote:
> Peter Geoghegan wrote:
>> I've had multiple complaints of apparent data loss on 9.3.2 customer
>> databases. There are 2 total, both complaints from the past week, one
>> of which I was able to confirm. The customer's complaint is that
>> certain rows are either visible or invisible, depending on whether an
>> index scan is used or a sequential scan (I confirmed this with an
>> EXPLAIN ANALYZE).
>
> The multixact bugs would cause tuples to be hidden at the heap level.
> If the tuples are visible in a seqscan, then these are more likely to be
> related to index problems, not multixact problem.

I guess I wasn't clear enough here: The row in question was visible
with a sequential scans but *not* with an index scan. So you have it
backwards here (understandably).

--
Peter Geoghegan

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