odbc_primarykeys return type

I am having difficulty obtaining a reply to the following questions: resource *odbc_primarykeys* ( resource connection_id, string qualifier, string owner, string table) resource *odbc_foreignkeys* ( resource connection_id, string pk_qualifier, string pk_owner, string pk_table, string fk_qualifier, string fk_owner, string fk_table) int *odbc_tables* ( resource connection_id [, string qualifier [, string owner [, string name [, string types]]]]) int *odbc_tableprivileges* ( resource connection_id [, string qualifier [, string owner [, string name]]]) The first two functions return "resource" and the second two functions return "int". Is there any difference? Using a postgresql database odbc_tables works fine. But with odbc_primarykeys I can not find a result. Any advice would be appreciated. Kevin