Re: pgsql: Reset master xmin when hot_standby_feedback disabled. - Mailing list pgsql-committers

From Andres Freund
Subject Re: pgsql: Reset master xmin when hot_standby_feedback disabled.
Date
Msg-id 20140528223640.GD27914@awork2.anarazel.de
Whole thread Raw
In response to pgsql: Reset master xmin when hot_standby_feedback disabled.  (Simon Riggs <simon@2ndQuadrant.com>)
Responses Re: pgsql: Reset master xmin when hot_standby_feedback disabled.  (Simon Riggs <simon@2ndQuadrant.com>)
List pgsql-committers
Hi,

On 2013-02-04 10:35:31 +0000, Simon Riggs wrote:
> Reset master xmin when hot_standby_feedback disabled.
> If walsender has xmin of standby then ensure we
> reset the value to 0 when we change from hot_standby_feedback=on
> to hot_standby_feedback=off.

Unless somebody protests I'd like to backpatch this change to 9.2 and
9.1. This imo is a bugfix, not a new feature. What currently happens <
9.3 when hot_standby_feedback is disabled after being enabled is that
the walsender's xmin horizon doesn't increase until disconnected. That's
pretty hard to diagnose and can cause severe problems.

Greetings,

Andres Freund

--
 Andres Freund                       http://www.2ndQuadrant.com/
 PostgreSQL Development, 24x7 Support, Training & Services


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