diff --git a/contrib/pg_upgrade/check.c b/contrib/pg_upgrade/check.c
new file mode 100644
index e400814..d32a84c
*** a/contrib/pg_upgrade/check.c
--- b/contrib/pg_upgrade/check.c
***************
*** 14,20 ****
  
  static void set_locale_and_encoding(ClusterInfo *cluster);
  static void check_new_cluster_is_empty(void);
- static void check_old_cluster_has_new_cluster_dbs(void);
  static void check_locale_and_encoding(ControlData *oldctrl,
  						  ControlData *newctrl);
  static void check_is_super_user(ClusterInfo *cluster);
--- 14,19 ----
*************** check_new_cluster(void)
*** 127,133 ****
  
  	check_new_cluster_is_empty();
  	check_for_prepared_transactions(&new_cluster);
- 	check_old_cluster_has_new_cluster_dbs();
  
  	check_loadable_libraries();
  
--- 126,131 ----
*************** check_new_cluster_is_empty(void)
*** 382,420 ****
  
  
  /*
-  *	If someone removes the 'postgres' database from the old cluster and
-  *	the new cluster has a 'postgres' database, the number of databases
-  *	will not match.  We actually could upgrade such a setup, but it would
-  *	violate the 1-to-1 mapping of database counts, so we throw an error
-  *	instead.  We would detect this as a database count mismatch during
-  *	upgrade, but we want to detect it during the check phase and report
-  *	the database name.
-  */
- static void
- check_old_cluster_has_new_cluster_dbs(void)
- {
- 	int			old_dbnum,
- 				new_dbnum;
- 
- 	for (new_dbnum = 0; new_dbnum < new_cluster.dbarr.ndbs; new_dbnum++)
- 	{
- 		for (old_dbnum = 0; old_dbnum < old_cluster.dbarr.ndbs; old_dbnum++)
- 			if (strcmp(old_cluster.dbarr.dbs[old_dbnum].db_name,
- 					   new_cluster.dbarr.dbs[new_dbnum].db_name) == 0)
- 				break;
- 		if (old_dbnum == old_cluster.dbarr.ndbs)
- 		{
- 			if (strcmp(new_cluster.dbarr.dbs[new_dbnum].db_name, "postgres") == 0)
- 				pg_log(PG_FATAL, "The \"postgres\" database must exist in the old cluster\n");
- 			else
- 				pg_log(PG_FATAL, "New cluster database \"%s\" does not exist in the old cluster\n",
- 					   new_cluster.dbarr.dbs[new_dbnum].db_name);
- 		}
- 	}
- }
- 
- 
- /*
   * create_script_for_old_cluster_deletion()
   *
   *	This is particularly useful for tablespace deletion.
--- 380,385 ----
*************** create_script_for_old_cluster_deletion(c
*** 462,468 ****
  				fprintf(script, RM_CMD " %s%s/PG_VERSION\n",
  				 os_info.tablespaces[tblnum], old_cluster.tablespace_suffix);
  
! 			for (dbnum = 0; dbnum < new_cluster.dbarr.ndbs; dbnum++)
  			{
  				fprintf(script, RMDIR_CMD " %s%s/%d\n",
  				  os_info.tablespaces[tblnum], old_cluster.tablespace_suffix,
--- 427,433 ----
  				fprintf(script, RM_CMD " %s%s/PG_VERSION\n",
  				 os_info.tablespaces[tblnum], old_cluster.tablespace_suffix);
  
! 			for (dbnum = 0; dbnum < old_cluster.dbarr.ndbs; dbnum++)
  			{
  				fprintf(script, RMDIR_CMD " %s%s/%d\n",
  				  os_info.tablespaces[tblnum], old_cluster.tablespace_suffix,
diff --git a/contrib/pg_upgrade/function.c b/contrib/pg_upgrade/function.c
new file mode 100644
index 0f80089..b154f03
*** a/contrib/pg_upgrade/function.c
--- b/contrib/pg_upgrade/function.c
*************** get_loadable_libraries(void)
*** 132,139 ****
  	int			totaltups;
  	int			dbnum;
  
! 	ress = (PGresult **)
! 		pg_malloc(old_cluster.dbarr.ndbs * sizeof(PGresult *));
  	totaltups = 0;
  
  	/* Fetch all library names, removing duplicates within each DB */
--- 132,138 ----
  	int			totaltups;
  	int			dbnum;
  
! 	ress = (PGresult **) pg_malloc(old_cluster.dbarr.ndbs * sizeof(PGresult *));
  	totaltups = 0;
  
  	/* Fetch all library names, removing duplicates within each DB */
diff --git a/contrib/pg_upgrade/relfilenode.c b/contrib/pg_upgrade/relfilenode.c
new file mode 100644
index 1aefd33..ad893be
*** a/contrib/pg_upgrade/relfilenode.c
--- b/contrib/pg_upgrade/relfilenode.c
*************** const char *
*** 34,55 ****
  transfer_all_new_dbs(DbInfoArr *old_db_arr,
  				   DbInfoArr *new_db_arr, char *old_pgdata, char *new_pgdata)
  {
! 	int			dbnum;
  	const char *msg = NULL;
  
  	prep_status("Restoring user relation files\n");
  
! 	if (old_db_arr->ndbs != new_db_arr->ndbs)
! 		pg_log(PG_FATAL, "old and new clusters have a different number of databases\n");
! 
! 	for (dbnum = 0; dbnum < old_db_arr->ndbs; dbnum++)
  	{
! 		DbInfo	   *old_db = &old_db_arr->dbs[dbnum];
! 		DbInfo	   *new_db = &new_db_arr->dbs[dbnum];
  		FileNameMap *mappings;
  		int			n_maps;
  		pageCnvCtx *pageConverter = NULL;
  
  		if (strcmp(old_db->db_name, new_db->db_name) != 0)
  			pg_log(PG_FATAL, "old and new databases have different names: old \"%s\", new \"%s\"\n",
  				   old_db->db_name, new_db->db_name);
--- 34,63 ----
  transfer_all_new_dbs(DbInfoArr *old_db_arr,
  				   DbInfoArr *new_db_arr, char *old_pgdata, char *new_pgdata)
  {
! 	int			old_dbnum, new_dbnum;
  	const char *msg = NULL;
  
  	prep_status("Restoring user relation files\n");
  
! 	/* Scan the old cluster databases and transfer their files */
! 	for (old_dbnum = new_dbnum = 0;
! 		 old_dbnum < old_db_arr->ndbs && new_dbnum < new_db_arr->ndbs;
! 		 old_dbnum++, new_dbnum++)
  	{
! 		DbInfo	   *old_db = &old_db_arr->dbs[old_dbnum];
! 		DbInfo	   *new_db = &new_db_arr->dbs[new_dbnum];
  		FileNameMap *mappings;
  		int			n_maps;
  		pageCnvCtx *pageConverter = NULL;
  
+ 		/*
+ 		 *	Advance past any databases that exist in the new cluster
+ 		 *	but not in the old, e.g. "postgres".
+ 		 */
+ 		while (strcmp(old_db->db_name, new_db->db_name) != 0 &&
+ 			   new_dbnum < new_db_arr->ndbs)
+ 			new_db = &new_db_arr->dbs[++new_dbnum];
+ 
  		if (strcmp(old_db->db_name, new_db->db_name) != 0)
  			pg_log(PG_FATAL, "old and new databases have different names: old \"%s\", new \"%s\"\n",
  				   old_db->db_name, new_db->db_name);