Implicit UDR execution of a user-defined aggregate

For example, suppose you create a UDA named uda and use it in the following SQL query:

select grp, uda(udt_col) FROM tab GROUP BY grp;

If the data type of column udt_col is a UDT whose aggregation requires a UDR call, the following operations can execute in parallel:

• Each group thread executes the aggregation UDR uda in parallel.
• If the GROUP BY column grp is a UDT column, the equal() UDR function on the UDT column executes in parallel by the scan thread for the hash repartitioning on the group by keys.
• If the table tab is fragmented, multiple scan threads can read the table in parallel.