Horton

Re: Old row version in hot chain become visible after a freeze

Jeff Frost <jeff@pgexperts.com>

View thread View on postgr.es
From: Jeff Frost <jeff@pgexperts.com>
To: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Michael Paquier <michael.paquier@gmail.com>, Peter Geoghegan <pg@bowt.ie>, "Wood, Dan" <hexpert@amazon.com>, "pgsql-bugs@postgresql.org" <pgsql-bugs@postgresql.org>, Andres Freund <andres@anarazel.de>
Date: 2017-09-07T04:45:45Z
Lists: pgsql-bugs 
> On Sep 6, 2017, at 8:23 PM, Jeff Frost <jeff@pgexperts.com> wrote:
> 
> 
> Any idea on how to identify affected rows on a running system?

I guess better questions would be:

Is it as simple as:

SELECT id, count(*) FROM foo GROUP BY id HAVING count(*) > 1;

Maybe also need to:

set enable_indexscan = 0;
set enable_indexonlyscan = 0;

before running the SELECT?

Is it possible to affect a DELETE or does it need to be a HOT updated row?

Commits

  1. Fix freezing of a dead HOT-updated tuple

  2. Fix potential data corruption during freeze

  3. Clarify the contract of partition_rbound_cmp().