PS Gotcha - Group Build and Aggregate functions

Group Build is a commonly used functionality within PeopleSoft HCM (I prefer Dynamic Groups in Time and Labor better for the extended flexibility, but that does not extend to the whole HCM product line). We had documented a limitation of the Group Build framework, earlier in this post.
And here is another gotcha while working on Group Build. The PS Queries that you use as an input to a Group definition cannot contain an aggregate function or unions.
Another interesting tip is that you can give Group build security access to only those OPRIDs that have an EMPLID attached to the OPRID. So, next time you login with a maintenance super-user id (like an id used to run scheduled batch processes) and do not have access to Groups in the Security by Group page, you know what is wrong!

And if anyone has questions on where to define a Group Build group, here is the navigation:
Setup HRMS > Common Definitions > Group Build

Extra reference document (requires Oracle support login):
Troubleshooting Group Build issues

https://support.oracle.com/epmos/faces/DocumentDisplay?id=655288.1

Learning of the day: Group Build and Future effective dates

Group Build functionality in PeopleSoft HCM can be used to group employees together based on flexible parameters. But, one limitation of Group Build is that it does not consider future effective dates, even if the parameters used to build the Group is designed to return future effective date. As mentioned in support.oracle.com (or customer connection or metalink, whatever you might want to call!), Group Build is designed to only consider current and historical effective dated rows. This is an important point to keep in mind while designing any process that involves Group Build - "Group Build does not consider future effective dates".