Improve the check for pg_catalog.unknown data type in pg_upgrade

The pg_upgrade check for pg_catalog.unknown type when upgrading from 9.6
had a couple of issues with domains and composite types - it detected
even composite types unused in objects with storage. So for example this
was enough to trigger an unnecessary pg_upgrade failure:

  CREATE TYPE unknown_composite AS (u pg_catalog.unknown)

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

  CREATE DOMAIN unknown_domain AS pg_catalog.unknown;
  CREATE TYPE unknown_composite_2 AS (u unknown_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.unknown type through a domain. So we missed cases like this

  CREATE TABLE t (u unknown_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 eaf900e842 for sql_identifier. Backpatch all
the way to 10, where the of pg_catalog.unknown data type was restricted.

Author: Tomas Vondra
Backpatch-to: 10-
Discussion: https://postgr.es/m/16045-673e8fa6b5ace196%40postgresql.org

diff --git a/src/bin/pg_upgrade/version.c b/src/bin/pg_upgrade/version.c
index be5f108f0ab8030575e8d882ce7b8ac83ef47275..b64171d275a38875c7feb939ddce5a7a1150c056 100644 (file)
--- a/src/bin/pg_upgrade/version.c
+++ b/src/bin/pg_upgrade/version.c
@@ -229,7 +229,8 @@ old_9_3_check_for_line_data_type_usage(ClusterInfo *cluster)
  *     mid-upgrade.  Worse, if there's a matview with such a column, the
  *     DDL reload will silently change it to "text" which won't match the
  *     on-disk storage (which is like "cstring").  So we *must* reject that.
- *     Also check composite types, in case they are used for table columns.
+ *     Also check composite types and domains on the "unknwown" type (even
+ *     combinations of both), in case they are used for table columns.
  *     We needn't check indexes, because "unknown" has no opclasses.
  */
 void
@@ -256,17 +257,40 @@ old_9_6_check_for_unknown_data_type_usage(ClusterInfo *cluster)
                DbInfo     *active_db = &cluster->dbarr.dbs[dbnum];
                PGconn     *conn = connectToServer(cluster, active_db->db_name);
 
+               /*
+                * The pg_catalog.unknown type may be wrapped in a domain or composite
+                * type, or both (9.3 did not allow domains on composite types, but
+                * there may be multi-level composite type). To detect these cases
+                * we need a recursive CTE.
+                */
                res = executeQueryOrDie(conn,
+                                                               "WITH RECURSIVE oids AS ( "
+               /* the pg_catalog.unknown type itself */
+                                                               "       SELECT 'pg_catalog.unknown'::pg_catalog.regtype AS oid "
+                                                               "       UNION ALL "
+                                                               "       SELECT * FROM ( "
+               /* domains on the type */
+                                                               "               WITH x AS (SELECT oid FROM oids) "
+                                                               "                       SELECT t.oid FROM pg_catalog.pg_type t, x WHERE typbasetype = x.oid AND typtype = 'd' "
+                                                               "                       UNION "
+               /* composite types containing the type */
+                                                               "                       SELECT t.oid FROM pg_catalog.pg_type t, pg_catalog.pg_class c, pg_catalog.pg_attribute a, x "
+                                                               "                       WHERE t.typtype = 'c' AND "
+                                                               "                                 t.oid = c.reltype AND "
+                                                               "                                 c.oid = a.attrelid AND "
+                                                               "                                 NOT a.attisdropped AND "
+                                                               "                                 a.atttypid = x.oid "
+                                                               "       ) foo "
+                                                               ") "
                                                                "SELECT n.nspname, c.relname, a.attname "
                                                                "FROM   pg_catalog.pg_class c, "
                                                                "               pg_catalog.pg_namespace n, "
                                                                "               pg_catalog.pg_attribute a "
                                                                "WHERE  c.oid = a.attrelid AND "
                                                                "               NOT a.attisdropped AND "
-                                                               "               a.atttypid = 'pg_catalog.unknown'::pg_catalog.regtype AND "
+                                                               "               a.atttypid IN (SELECT oid FROM oids) AND "
                                                                "               c.relkind IN ("
                                                                CppAsString2(RELKIND_RELATION) ", "
-                                                               CppAsString2(RELKIND_COMPOSITE_TYPE) ", "
                                                                CppAsString2(RELKIND_MATVIEW) ") AND "
                                                                "               c.relnamespace = n.oid AND "
                /* exclude possible orphaned temp tables */