Specifies how to combine UNION ALL input.


UNION ALL /*+UTYPE(union-type)*/



One of the following arguments:

  • U: Concatenates UNION ALL input (default).
  • M: Merges UNION ALL input in the same sort order as the source query results. This option requires all input from the source queries to use the same sort order; otherwise, Vertica throws a warning and concatenates the UNION ALL input.

    The optimizer relies upon the query or DDL to verify whether input data is sorted, rather than the actual runtime order of the data.


Queries that include the UTYPE hint must also include the SYNTACTIC_JOIN hint. Otherwise, the optimizer ignores the UTYPE hint and throws a warning.