Virtual Schemas are able to push certain aspects of a query into the source system, which can result in improved performance for the virtual schema query.
The pushdown of COUNT(*) and COUNT(exp) was already supported.
Virtual schemas now support the pushdown of COUNT of a tuple, e.g. COUNT((exp1, exp2)), into the source system. The virtual schema API has been extended to support this.
To take advantage of this improvement, you must
- update the database to the fix version and
- update the virtual schema adapter.