pg_upgrade: warn about extensions that need updating

Also create a script that can be run to update them.

Reported-by: Dave Cramer

Discussion: https://postgr.es/m/CADK3HHKawwbOcGwMGnDuAf3-U8YfvTcS8jqDv3UM=niijs3MMA@mail.gmail.com

Backpatch-through: 9.6

src/bin/pg_upgrade/check.c

@@ -241,6 +241,8 @@ issue_warnings_and_set_wal_level(void)
 	if (GET_MAJOR_VERSION(old_cluster.major_version) <= 906)
 		old_9_6_invalidate_hash_indexes(&new_cluster, false);
 
+	report_extension_updates(&new_cluster);
+
 	stop_postmaster(false);
 }
 

src/bin/pg_upgrade/pg_upgrade.h

@@ -455,6 +455,7 @@ void		old_9_6_invalidate_hash_indexes(ClusterInfo *cluster,
 											bool check_mode);
 
 void		old_11_check_for_sql_identifier_data_type_usage(ClusterInfo *cluster);
+void		report_extension_updates(ClusterInfo *cluster);
 
 /* parallel.c */
 void		parallel_exec_prog(const char *log_file, const char *opt_log_file,

src/bin/pg_upgrade/version.c

@@ -468,3 +468,81 @@ old_11_check_for_sql_identifier_data_type_usage(ClusterInfo *cluster)
 	else
 		check_ok();
 }
+
+
+/*
+ * report_extension_updates()
+ *	Report extensions that should be updated.
+ */
+void
+report_extension_updates(ClusterInfo *cluster)
+{
+	int			dbnum;
+	FILE	   *script = NULL;
+	bool		found = false;
+	char	   *output_path = "update_extensions.sql";
+
+	prep_status("Checking for extension updates");
+
+	for (dbnum = 0; dbnum < cluster->dbarr.ndbs; dbnum++)
+	{
+		PGresult   *res;
+		bool		db_used = false;
+		int			ntups;
+		int			rowno;
+		int			i_name;
+		DbInfo	   *active_db = &cluster->dbarr.dbs[dbnum];
+		PGconn	   *conn = connectToServer(cluster, active_db->db_name);
+
+		/* find hash indexes */
+		res = executeQueryOrDie(conn,
+								"SELECT name "
+								"FROM pg_available_extensions "
+								"WHERE installed_version != default_version"
+			);
+
+		ntups = PQntuples(res);
+		i_name = PQfnumber(res, "name");
+		for (rowno = 0; rowno < ntups; rowno++)
+		{
+			found = true;
+
+			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)
+			{
+				PQExpBufferData connectbuf;
+
+				initPQExpBuffer(&connectbuf);
+				appendPsqlMetaConnect(&connectbuf, active_db->db_name);
+				fputs(connectbuf.data, script);
+				termPQExpBuffer(&connectbuf);
+				db_used = true;
+			}
+			fprintf(script, "ALTER EXTENSION %s UPDATE;\n",
+					quote_identifier(PQgetvalue(res, rowno, i_name)));
+		}
+
+		PQclear(res);
+
+		PQfinish(conn);
+	}
+
+	if (script)
+		fclose(script);
+
+	if (found)
+	{
+		report_status(PG_REPORT, "notice");
+		pg_log(PG_REPORT, "\n"
+			   "Your installation contains extensions that should be updated\n"
+			   "with the ALTER EXTENSION command.  The file\n"
+			   "    %s\n"
+			   "when executed by psql by the database superuser will update\n"
+			   "these extensions.\n\n",
+			   output_path);
+	}
+	else
+		check_ok();
+}