over(… groups between …)

The over clause accepts groups framing, which limits the scope of the window function to the rows between the specified number of distinct values in the order by keys.

SELECT *, COUNT(*) OVER(ORDER BY val
                       GROUPS BETWEEN 1 PRECEDING
                                  AND CURRENT ROW)
  FROM …

The frame defined by this groups clause covers all rows whose order by key falls between the next smaller value of the current row’s order by key (between 1 preceding) and the current rows order by key (and current row).

Meaningful framing requires an order by clause in over as well. Note that this order by clause does not necessarily affect the order of rows in the final result. If you want the result in a specific order, add an order by clause at the outermost query level.

Related

• Sub clauses:

  • over(partition by …)

  • over(order by …)

  • Framing:

    • over(… rows between …)

    • over(… range between …) (numeric), over(… range between …) (datetime)

    • Frame exclusion:

      • over(… exclude no others)

      • over(… exclude current row)

      • over(… exclude group)

      • over(… exclude ties)

• Product specific extensions: over(range between…) (strings, multi-columns)

Normative References

The groups framing is defined in ISO/IEC 9075-2:2023 as part of optional feature T620, “WINDOW clause: GROUPS option”.