Re: Enabling Checksums

Bruce Momjian <bruce@momjian.us>

From: Bruce Momjian <bruce@momjian.us>

To: Jim Nasby <jim@nasby.net>

Cc: Greg Smith <greg@2ndQuadrant.com>, Simon Riggs <simon@2ndQuadrant.com>, Tom Lane <tgl@sss.pgh.pa.us>, Andres Freund <andres@2ndquadrant.com>, Ants Aasma <ants@cybertec.at>, Heikki Linnakangas <hlinnakangas@vmware.com>, Jeff Davis <pgsql@j-davis.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>

Date: 2013-03-25T13:25:44Z

Lists: pgsql-hackers

On Fri, Mar 22, 2013 at 11:35:35PM -0500, Jim Nasby wrote:
> On 3/20/13 8:41 AM, Bruce Momjian wrote:
> >Also, if a users uses checksums in 9.3, could they initdb without
> >checksums in 9.4 and use pg_upgrade?  As coded, the pg_controldata
> >checksum settings would not match and pg_upgrade would throw an
> >error, but it might be possible to allow this, i.e. you could go from
> >checksum to no checksum initdb clusters, but not from no checksum to
> >checksum.  I am wondering if the patch should reflect this.
>
> If the docs don't warn about this, they should, but I don't think it's
> the responsibility of this patch to deal with that problem. The reason
> I don't believe this patch should deal with it is because that is a
> known, rather serious, limitation of pg_upgrade. It's something about
> pg_upgrade that just needs to be fixed, regardless of what patches
> might make the situation worse.

Huh?  It wasn't a "serious limitation" of pg_upgrade until this patch. 
What limitation does pg_upgrade have regardless of this patch?

-- 
  Bruce Momjian  <bruce@momjian.us>        http://momjian.us
  EnterpriseDB                             http://enterprisedb.com

  + It's impossible for everything to be true. +