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

src/bin/pg_dump/pg_dumpall.c

@@ -1412,6 +1412,24 @@ dumpCreateDB(PGconn *conn)
 
 			appendPQExpBufferStr(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, "\\connect template1\n");
+			else
+				appendPQExpBuffer(buf, "\\connect postgres\n");
+
+			appendPQExpBuffer(buf, "ALTER DATABASE %s SET TABLESPACE %s;\n",
+							  fdbname, fmtId(dbtablespace));
+
+			/* connect to original database */
+			appendPQExpBuffer(buf, "\\connect %s\n", fdbname);
+		}
 
 		if (binary_upgrade)
 		{

src/bin/pg_upgrade/info.c

@@ -140,6 +140,7 @@ 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)
 	{
 		/*
@@ -147,16 +148,24 @@ create_rel_filename_map(const char *old_data, const char *new_data,
 		 * exist in the data directories.
 		 */
 		map->old_tablespace = old_data;
-		map->new_tablespace = new_data;
 		map->old_tablespace_suffix = "/base";
-		map->new_tablespace_suffix = "/base";
 	}
 	else
 	{
 		/* relation belongs to a tablespace, so use the tablespace location */
 		map->old_tablespace = old_rel->tablespace;
-		map->new_tablespace = new_rel->tablespace;
 		map->old_tablespace_suffix = old_cluster.tablespace_suffix;
+	}
+
+	/* Do the same for new tablespaces */
+	if (strlen(new_rel->tablespace) == 0)
+	{
+		map->new_tablespace = new_data;
+		map->new_tablespace_suffix = "/base";
+	}
+	else
+	{
+		map->new_tablespace = new_rel->tablespace;
 		map->new_tablespace_suffix = new_cluster.tablespace_suffix;
 	}