The base global temporary table definition and all its materialized instances are to be dropped when they are not being accessed by any other transactions.
ALL is not valid when specified for any database object other than a global temporary table.
ALL is not valid when specified with the TEMPORARY keyword.
Take care in using this option because the time required for all open transactions accessing this object to commit might be significant.
If you do not specify ALL and if the global temporary table is materialized in any other session, Teradata Database aborts the request.