From 5349d32d91ce0160e08405387a30ec53ea434944 Mon Sep 17 00:00:00 2001
From: Justin Pryzby <pryzbyj@telsasoft.com>
Date: Fri, 10 Jun 2022 11:17:36 -0500
Subject: [PATCH] WIP: pg_upgrade --check: detect aggregates for pre-pg14

This fails when upgrading from pre-14 (as expected), but it should fail during
pg_upgrade --check.

CREATE AGGREGATE array_accum(anyelement) (sfunc=array_append, stype=anyarray, initcond='{}');

See also:
9e38c2bb5093ceb0c04d6315ccd8975bd17add66
97f73a978fc1aca59c6ad765548ce0096d95a923
---
 src/bin/pg_upgrade/check.c | 97 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 97 insertions(+)

diff --git a/src/bin/pg_upgrade/check.c b/src/bin/pg_upgrade/check.c
index ace7387edaf..4fd47e0b59a 100644
--- a/src/bin/pg_upgrade/check.c
+++ b/src/bin/pg_upgrade/check.c
@@ -31,6 +31,7 @@ static void check_for_jsonb_9_4_usage(ClusterInfo *cluster);
 static void check_for_pg_role_prefix(ClusterInfo *cluster);
 static void check_for_new_tablespace_dir(ClusterInfo *new_cluster);
 static void check_for_user_defined_encoding_conversions(ClusterInfo *cluster);
+static void check_for_old_aggregates(ClusterInfo *cluster);
 static char *get_canonical_locale_name(int category, const char *locale);
 
 
@@ -122,6 +123,12 @@ check_and_dump_old_cluster(bool live_check)
 	if (GET_MAJOR_VERSION(old_cluster.major_version) <= 1300)
 		check_for_user_defined_postfix_ops(&old_cluster);
 
+	/*
+	 * Pre-PG 14 changed from anyarray to anycompatibelarray.
+	 */
+	if (GET_MAJOR_VERSION(old_cluster.major_version) <= 1300)
+		check_for_old_aggregates(&old_cluster);
+
 	/*
 	 * Pre-PG 12 allowed tables to be declared WITH OIDS, which is not
 	 * supported anymore. Verify there are none, iff applicable.
@@ -775,6 +782,96 @@ check_proper_datallowconn(ClusterInfo *cluster)
 }
 
 
+/*
+ *	check_for_old_aggregates()
+ *
+ *	Make sure there are no aggregates using anyelement which need to be changed
+ *	to anycompatible.
+ */
+static void
+check_for_old_aggregates(ClusterInfo *cluster)
+{
+	PGresult   *res;
+	PGconn	   *conn = connectToServer(cluster, "template1");
+	FILE	   *script = NULL;
+	char		output_path[MAXPGPATH];
+
+	prep_status("Checking for old aggregates using anyelement");
+
+	snprintf(output_path, sizeof(output_path), "%s/%s",
+			 log_opts.basedir,
+			 "databases_with_old_aggregates.txt");
+
+	for (int dbnum = 0; dbnum < cluster->dbarr.ndbs; dbnum++)
+	{
+		bool		db_used = false;
+		DbInfo	   *active_db = &cluster->dbarr.dbs[dbnum];
+		PGconn	   *conn = connectToServer(cluster, active_db->db_name);
+		int			ntups;
+		int			i_nspname,
+					i_proname;
+
+		res = executeQueryOrDie(conn,
+								"SELECT pn.nspname, p.proname FROM "
+								"pg_proc p "
+								"JOIN pg_aggregate a ON a.aggfnoid=p.oid "
+								"JOIN pg_proc q ON q.oid=a.aggtransfn "
+								"JOIN pg_namespace pn ON pn.oid=p.pronamespace "
+								"JOIN pg_namespace qn ON qn.oid=q.pronamespace "
+								"WHERE pn.nspname != 'pg_catalog' "
+								"AND qn.nspname = 'pg_catalog' "
+								"AND 'anyelement'::regtype=ANY(q.proargtypes) "
+								"AND q.proname IN ('array_append',"
+								" 'array_prepend', 'array_cat', "
+								" 'array_position', 'array_positions', "
+								" 'array_remove', 'array_replace', "
+								" 'width_bucket');");
+								// "AND aggtranstype='anyarray'::regtype
+								/* Before v11, used proisagg=true, and afterwards uses prokind='a' */
+
+		ntups = PQntuples(res);
+
+		i_nspname = PQfnumber(res, "nspname");
+		i_proname = PQfnumber(res, "proname");
+
+		for (int rowno = 0; rowno < ntups; rowno++)
+		{
+			if (script == NULL && (script = fopen_priv(output_path, "w")) == NULL)
+				pg_fatal("could not open file \"%s\": %s\n",
+						 output_path, strerror(errno));
+
+			if (!db_used)
+			{
+				db_used = true;
+				fprintf(script, "In database: %s\n", active_db->db_name);
+			}
+
+			fprintf(script, "  %s.%s\n",
+					PQgetvalue(res, rowno, i_nspname),
+					PQgetvalue(res, rowno, i_proname));
+		}
+
+		PQclear(res);
+	}
+
+	PQfinish(conn);
+
+	if (script)
+	{
+		fclose(script);
+		pg_log(PG_REPORT, "fatal\n");
+		pg_fatal("The cluster contains aggregate functions using anyelement.\n"
+				"User defined aggregates which refer to built-in functions with\n"
+				"arguments of type 'anyelement' must be dropped before upgrading\n"
+				"and restored afterwards to refer to the corresponding functions\n"
+				"with arguments of type 'anycompatible'.\n"
+				"A list of the problem functions is in the file:\n"
+				"    %s\n\n", output_path);
+	}
+	else
+		check_ok();
+}
+
 /*
  *	check_for_prepared_transactions()
  *
-- 
2.17.1