Add check to refuse upgrades of external partitions

Partitioned tables with external tables in the partition hierarchy
cannot be upgraded since external partition management is prohibited
in utility mode (the partitioning system catalogs are not replicated
to the segments). Add a check for external partitions and abort the
upgrade if found.

contrib/pg_upgrade/README.gpdb

@@ -52,3 +52,7 @@ synchronization.
   - AO table segment files will be rewritten when a segment containing numeric
     attributes are written to from database operations.
 
+* External partitions are not supported since management of external partitions
+  is not allowed in utility mode. All external partitions must be either moved
+  out of the partition hierarchy with ALTER TABLE EXCHANGE, or dropped, prior
+  to the upgrade.

contrib/pg_upgrade/check.c

@@ -18,6 +18,7 @@ static void check_proper_datallowconn(migratorContext *ctx, Cluster whichCluster
 static void check_for_isn_and_int8_passing_mismatch(migratorContext *ctx,
 												Cluster whichCluster);
 static void check_for_reg_data_type_usage(migratorContext *ctx, Cluster whichCluster);
+static void check_external_partition(migratorContext *ctx);
 
 
 /*
@@ -98,6 +99,7 @@ check_old_cluster(migratorContext *ctx, bool live_check,
 	check_proper_datallowconn(ctx, CLUSTER_OLD);
 	check_for_reg_data_type_usage(ctx, CLUSTER_OLD);
 	check_for_isn_and_int8_passing_mismatch(ctx, CLUSTER_OLD);
+	check_external_partition(ctx);
 
 	/* old = PG 8.3 checks? */
 	/*
@@ -769,3 +771,91 @@ check_for_reg_data_type_usage(migratorContext *ctx, Cluster whichCluster)
 	else
 		check_ok(ctx);
 }
+
+/*
+ *	check_external_partition
+ *
+ *	External tables cannot be included in the partitioning hierarchy during the
+ *	initial definition with CREATE TABLE, they must be defined separately and
+ *	injected via ALTER TABLE EXCHANGE. The partitioning system catalogs are
+ *	however not replicated onto the segments which means ALTER TABLE EXCHANGE
+ *	is prohibited in utility mode. This means that pg_upgrade cannot upgrade a
+ *	cluster containing external partitions, they must be handled manually
+ *	before/after the upgrade.
+ *
+ *	Check for the existence of external partitions and refuse the upgrade if
+ *	found.
+ */
+static void
+check_external_partition(migratorContext *ctx)
+{
+	ClusterInfo *old_cluster = &ctx->old;
+	char		query[QUERY_ALLOC];
+	char		output_path[MAXPGPATH];
+	FILE	   *script = NULL;
+	bool		found = false;
+	int			dbnum;
+
+	prep_status(ctx, "Checking for external tables used in partitioning");
+
+	snprintf(output_path, sizeof(output_path), "%s/external_partitions.txt",
+			 ctx->cwd);
+	/*
+	 * We need to query the inheritance catalog rather than the partitioning
+	 * catalogs since they are not available on the segments.
+	 */
+	snprintf(query, sizeof(query),
+			 "SELECT cc.relname, c.relname AS partname, c.relnamespace "
+			 "FROM   pg_inherits i "
+			 "       JOIN pg_class c ON (i.inhrelid = c.oid AND c.relstorage = '%c') "
+			 "       JOIN pg_class cc ON (i.inhparent = cc.oid);",
+			 RELSTORAGE_EXTERNAL);
+
+	for (dbnum = 0; dbnum < old_cluster->dbarr.ndbs; dbnum++)
+	{
+		PGresult   *res;
+		int			ntups;
+		int			rowno;
+		DbInfo	   *active_db = &old_cluster->dbarr.dbs[dbnum];
+		PGconn	   *conn;
+
+		conn = connectToServer(ctx, active_db->db_name, CLUSTER_OLD);
+		res = executeQueryOrDie(ctx, conn, query);
+
+		ntups = PQntuples(res);
+
+		if (ntups > 0)
+		{
+			found = true;
+
+			if (script == NULL && (script = fopen(output_path, "w")) == NULL)
+				pg_log(ctx, PG_FATAL, "Could not create necessary file:  %s\n",
+					   output_path);
+
+			for (rowno = 0; rowno < ntups; rowno++)
+			{
+				fprintf(script, "External partition \"%s\" in relation \"%s\"\n",
+						PQgetvalue(res, rowno, PQfnumber(res, "partname")),
+						PQgetvalue(res, rowno, PQfnumber(res, "relname")));
+			}
+		}
+
+		PQclear(res);
+		PQfinish(conn);
+	}
+	if (found)
+	{
+		fclose(script);
+		pg_log(ctx, PG_REPORT, "fatal\n");
+		pg_log(ctx, PG_FATAL,
+			   "| Your installation contains partitioned tables with external\n"
+			   "| tables as partitions.  These partitions need to be removed\n"
+			   "| from the partition hierarchy before the upgrade.  A list of\n"
+			   "| external partitions to remove is in the file:\n"
+			   "| \t%s\n\n", output_path);
+	}
+	else
+	{
+		check_ok(ctx);
+	}
+}

contrib/pg_upgrade/pg_upgrade.h

@@ -38,6 +38,9 @@
 #define DB_DUMP_FILE		"pg_upgrade_dump_db.sql"
 #define ARRAY_DUMP_FILE		"pg_upgrade_dump_arraytypes.sql"
 
+/* needs to be kept in sync with pg_class.h */
+#define RELSTORAGE_EXTERNAL	'x'
+
 #ifndef WIN32
 #define pg_copy_file		copy_file
 #define pg_mv_file			rename