If you have "unstructured data", you're in for a hellish ride. It's usually much better to enforce the structure beforehand and set up a process by which the structure schema can be expanded in a quick and not too formal way.

I think that Postgres nowadays even has extensions to run (XPath?) queries against the jsonb data type, but I wouldn't know how DBIx::Class can be coerced into actually creating the SQL needed to query that. The Postgres documentation on JSON (as found via Google) shows the SQL needed for querying data that is only available in the jsonb column.

Update: Updated Pg doc link to the current version.