Re: Version number for pg_control

On 15 July 2016 at 23:54, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:

> While researching a pgsql-general question, I noticed that commit
> 73c986adde5d73a5e2555da9b5c8facedb146dcd added several new fields
> to pg_control without bothering to touch PG_CONTROL_VERSION. Thus,
> PG_CONTROL_VERSION is still "942" even though the file contents
> are not at all compatible with 9.4.
>
> It's way too late to do anything about this in 9.5.

Is it?

If PG_VERSION and the catalog version are correct for 9.5, the next point
release could update pg_control's version, accepting the old one during
recovery but only writing the new one.

Whether we should is another matter, since that means people can't
downgrade to old point releases, replicas will break if they upgrade the
master before the replicas, etc. It doesn't seem worth the cost/benefit.

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