pg_dump, pg_upgrade: allow postgres/template1 tablespace moves

Modify pg_dump to restore postgres/template1 databases to non-default
tablespaces by switching out of the database to be moved, then switching
back.

Also, to fix potentially cases where the old/new tablespaces might not
match, fix pg_upgrade to process new/old tablespaces separately in all
cases.

Report by Marti Raudsepp

Patch by Marti Raudsepp, me

Backpatch through 9.0

contrib/pg_upgrade/info.c

@@ -92,6 +92,7 @@ create_rel_filename_map(const char *old_data, const char *new_data,
 						const RelInfo *old_rel, const RelInfo *new_rel,
 						FileNameMap *map)
 {
+	/* In case old/new tablespaces don't match, do them separately. */
 	if (strlen(old_rel->tablespace) == 0)
 	{
 		/*
@@ -100,14 +101,27 @@ create_rel_filename_map(const char *old_data, const char *new_data,
 		 */
 		snprintf(map->old_dir, sizeof(map->old_dir), "%s/base/%u", old_data,
 				 old_db->db_oid);
-		snprintf(map->new_dir, sizeof(map->new_dir), "%s/base/%u", new_data,
-				 new_db->db_oid);
 	}
 	else
 	{
 		/* relation belongs to a tablespace, so use the tablespace location */
 		snprintf(map->old_dir, sizeof(map->old_dir), "%s%s/%u", old_rel->tablespace,
 				 old_cluster.tablespace_suffix, old_db->db_oid);
+	}
+
+	/* Do the same for new tablespaces */
+	if (strlen(new_rel->tablespace) == 0)
+	{
+		/*
+		 * relation belongs to the default tablespace, hence relfiles should
+		 * exist in the data directories.
+		 */
+		snprintf(map->new_dir, sizeof(map->new_dir), "%s/base/%u", new_data,
+				 new_db->db_oid);
+	}
+	else
+	{
+		/* relation belongs to a tablespace, so use the tablespace location */
 		snprintf(map->new_dir, sizeof(map->new_dir), "%s%s/%u", new_rel->tablespace,
 				 new_cluster.tablespace_suffix, new_db->db_oid);
 	}

src/bin/pg_dump/pg_dumpall.c

@@ -1326,6 +1326,28 @@ dumpCreateDB(PGconn *conn)
 				appendPQExpBuffer(buf, ";\n");
 			}
 		}
+		else if (strcmp(dbtablespace, "pg_default") != 0 && !no_tablespaces)
+		{
+			/*
+			 * Cannot change tablespace of the database we're connected to,
+			 * so to move "postgres" to another tablespace, we connect to
+			 * "template1", and vice versa.
+			 */
+			if (strcmp(dbname, "postgres") == 0)
+				appendPQExpBuffer(buf, "%s\\connect template1\n",
+					/* Add a space before \\connect so pg_upgrade can split */
+					binary_upgrade ? " " : "");
+			else
+				appendPQExpBuffer(buf, "%s\\connect postgres\n",
+					binary_upgrade ? " " : "");
+
+			appendPQExpBuffer(buf, "ALTER DATABASE %s SET TABLESPACE %s;\n",
+							  fdbname, fmtId(dbtablespace));
+
+			/* connect to original database */
+			appendPQExpBuffer(buf, "%s\\connect %s\n",
+				binary_upgrade ? " " : "", fdbname);
+		}
 
 		if (binary_upgrade)
 		{