One of my colleagues recently posed a very interesting PEGA question : suppose there are two sets of records called A and B (A and B might or might not be of the same class), and the requirement is to create a UNION of these two record sets and show it in a screen as a common list (A+B).

Now, a quick search within PDN told me the same answer over and over again : there is no straightforward OOTB method to get the data like this. The answer which has got best response is that of creating a View in the database , and do a Union of the records directly within the DB. But creation of a view is sometimes inconvenient : in large financial companies, having write access to DB is not always possible , not to mention exporting it to higher environments. Sub Reports and Joins within Report Definition were also attempted, but did not work out.

A small digging within PEGA provided a very convenient solution , and that too Out-of-the-box: usage of Aggregate Sources within Data pages . This functionality allows UNION of disparate data sets (which can be in the form of Report result or Connector response), and merge them directly as a resultset within the Data Page response. The solution is scalable (addition of a record set C would not break it, unlike a DB view which needs to be re-written), and whats more : you can add conditions to the aggregation and make the same Data page work for various data combinations !

If you find any other elegant solutions present for the same use case within PEGA , do let me know...