From: Tom Lane <tgl@sss.pgh.pa.us>
To: Robert Pang <robertpang@google.com>
cc: pgsql-admin@lists.postgresql.org
Subject: Re: Are extensions downgrade-safe?
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Comments: In-reply-to Robert Pang <robertpang@google.com>
	message dated "Tue, 13 Aug 2019 12:01:12 -0700"
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Date: Tue, 13 Aug 2019 15:23:01 -0400
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Robert Pang <robertpang@google.com> writes:
> In PostgreSQL, there are times where a new version of an extension is
> included in a minor-version upgrade. If I do a minor-version upgrade of my
> PG database, upgrade the version of the extension and then have a need to
> revert (downgrade) to the old PG minor version, what should I do with the
> extension?

It'd really depend on what the particular extension upgrade script did.
A lot of the time you wouldn't have any issue, but there are probably
cases where reversing the effect of the upgrade script would be advisable.

We don't prepare downgrade scripts for the contrib modules; the question
comes up so seldom that it doesn't seem worth the maintenance effort.
But you could likely make one by studying the upgrade script and reversing
whatever it did.

			regards, tom lane