Alvaro Herrera <alvherre@alvh.no-ip.org> writes:
> Tom Lane wrote:
>> Was there any real discussion of whether we could get away with that
>> in the back branches? My opinion is no. It's not even clear to me
>> that this is acceptable in HEAD --- isn't it going to create huge
>> problems for pg_upgrade?
> This was discussed upthread and the solution found was "objects need to
> be rebuilt, indexes need to be reindexed". The point of Alexander's
> query was to find affected objects that need such treatment. Teodor
> explicitly disregarded any change in pg_upgrade because the database
> you're upgrading *from* is supposed to have gotten indexes reindexed,
> etc.
I don't think that is really going to be acceptable. People do not like
minor version updates that break their databases. If we start doing
that we're going to find people refusing to apply minor updates, which
is not a place we want to be.
What we've done in the past for comparable situations is to make the
change in a new major version and teach pg_upgrade to detect and report
the need for changes --- in this case, it might do something like create
a script of REINDEX commands for the affected indexes. See e.g.
old_9_6_invalidate_hash_indexes().
regards, tom lane