Re: preserving db/ts/relfilenode OIDs across pg_upgrade (was Re: storing an explicit nonce)

On Thu, Aug 26, 2021 at 01:20:38PM -0400, Robert Haas wrote:
> So I think this proposed change is in the safe direction. If
> relfilenodes were currently preserved and we wanted to make them not
> be preserved, then I think you would be quite right to say "whoa,
> whoa, that could be a problem." Indeed it could. If anyone then in the
> future wanted to introduce a dependency on them staying the same, they
> would have a problem. However, nothing in the server itself can care
> about relfilenodes - or anything else - being *different* across a
> pg_upgrade. The whole point of pg_upgrade is to make it feel like you
> have the same database after you run it as you did before you ran it,
> even though under the hood a lot of surgery has been done. Barring
> bugs, you can never be sad about there being too LITTLE difference
> between the post-upgrade database and the pre-upgrade database.

Yes, this makes sense, and it is good we have stated the possible
benefits now:

*  pgBackRest
*  pg_upgrade diagnostics
*  TDE (maybe)

We can eventually evaluate the value of this based on those items.

-- 
  Bruce Momjian  <bruce@momjian.us>        https://momjian.us
  EDB                                      https://enterprisedb.com

  If only the physical world exists, free will is an illusion.