We have a user to use the Materialized view to improve performance. for individual query of those tables, it is pretty fast. But he built a view that will join/union of 17 tables(all from the materialized view) and it is not so fast.

It took him 35 seconds to finish the query, while if he bypass the Materialized view and send the same query to use tables directly from data base, it only took 16 seconds.

Is this because the database implementation of join/union is more efficient? Is there any way to improve this with Materialized view tables from Teiid?

thanks

Kevin