Looking at your example class, and maybe its not practical as we aren't seeing the entire context of your real world usage but might you see better resuilts if you were using instead of a composite index on prop1, prop2, prop3 but rahter bitmap indices on prop1 as it seems like it is the field name and would have a suffeceintly small number of values, a bitmap index on prop2, and a traditional index on prop3.  

If you were to show the query plan that would also provide some insight.

I would imagine if you have a license from Intersystems you could install Cache, mount the DB, and then the next question is "Was the application developed back in 2017" with an SQL interface, ie are there SQL tables that exist for the database that you have?"  If so you could connect to the db via ODBC and extract the data.

If not then that's a much large endeavor as you would need to have the tables defined and depending on how much meta-data/documentation you have for the data that could be quite involved.

Joel,

That's assuming your class query is based on %SQLQuery.  If your class query is based on %Query then you could have a single class query.