Contents Index Hash group by Indexed group by

ASA SQL User's Guide
  Query Optimization and Execution
    Query execution algorithms
      Grouping

Ordered group by

The ordered group by reads an input that is ordered by the grouping columns. As each row is read, it is compared to the previous row. If the grouping columns match, then the current group is updated; otherwise, the current group is output and a new group is started.

Contents Index Hash group by Indexed group by