Yes, this is almost certainly the same problem. The studydata table in 10.3 is now a union of hard tables rather than a physical table.

The query you sent last time is the one that is causing the problem.

I don't have your data & I know that Michael wanted to try & repro with the same data. Alternately we could try to isolate the problem in the query you sent last time by sending portions of the UNION clause to postgres directly.