src

The pg_upgrade check for pg_catalog.line data type when upgrading from
9.3 had a couple of issues with domains and composite types. Firstly, it
triggered false positives for composite types unused in objects with
storage. This was enough to trigger an unnecessary pg_upgrade failure:

  CREATE TYPE line_composite AS (l pg_catalog.line)

On the other hand, this only happened with composite types directly on
the pg_catalog.line data type, but not with a domain. So this was not
detected

  CREATE DOMAIN line_domain AS pg_catalog.line;
  CREATE TYPE line_composite_2 AS (l line_domain);

unlike the first example. These false positives and inconsistencies are
unfortunate, but what's worse we've failed to detected objects using the
pg_catalog.line data type through a domain. So we missed cases like this

  CREATE TABLE t (l line_composite_2);

The consequence is clusters broken after a pg_upgrade.

This fixes these false positives and false negatives by using the same
recursive CTE introduced by eaf900e8 for sql_identifier. 9.3 did not
support domains on composite types, but we can still have multi-level
composite types.

Backpatch all the way to 9.4, where the format for pg_catalog.line data
type changed.

Author: Tomas Vondra
Backpatch-to: 9.4-
Discussion: https://postgr.es/m/16045-673e8fa6b5ace196%40postgresql.org