Date: Thu, 10 Oct 2019 01:28:36 +0200
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: buschmann@nidsa.net, pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #16045: vacuum_db crash and illegal memory alloc after
 pg_upgrade from PG11 to PG12
Message-ID: <20191009232836.jg77wccqwy5fgs6s@development>
References: <16045-673e8fa6b5ace196@postgresql.org>
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 <20191009141841.my6k44wfiaquj3ks@development>
 <20191009230759.ge66neof5qj627a2@development>
 <19314.1570663125@sss.pgh.pa.us>
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On Wed, Oct 09, 2019 at 07:18:45PM -0400, Tom Lane wrote:
>Tomas Vondra <tomas.vondra@2ndquadrant.com> writes:
>> Well, I think I found the root cause. It's because of 7c15cef86d, which
>> changed the definition of sql_identifier so that it's a domain over name
>> instead of varchar.
>
>Ah...
>
>> Not sure what to do about this :-(
>
>Fortunately, there should be close to zero people with user tables
>depending on sql_identifier.  I think we should just add a test in
>pg_upgrade that refuses to upgrade if there are any such columns.
>It won't be the first such restriction.
>

Hmmm, yeah.  I agree the number of people using sql_identifier in user
tables is low, but OTOH we got this report within a week after release,
so maybe it's higher than we think.

Another option would be to teach pg_upgrade to switch the columns to
'text' or 'varchar', not sure if that's possible or how much work would
that be.

regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services