# April 6, 2022 release notes¶

## OPAL¶

### group_by() a path within an object value¶

The group_by() function already allows grouping results by the value of a specified field. Now you can group by the value of a specific element in an object-typed field. For example, group by the values in tags.clusterUid rather than all of the possible values in the tags field. For details, see the examples in the group_by() documentation.

### Using a timestamp field as part of a primary key¶

The set_primary_key() verb now supports using a time field as part of a primary key. While this is not a typical use, it is occasionally useful if you need to generate resources that contain only one interval each.

Note

set_primary_key is a low-level operation that requires some care in use. In most cases, you will more easily accomplish your goal using make_resource, update_resource, timechart, or make_event.