We should provide users a way to understand how their query will be executed and some information on the amount of work that will be performed.
Explain statements are the most common way to do that.
A CEP Draft has been open for that: (DRAFT) CEP-4: Explain. This draft propose to add support for EXPLAIN and EXPLAIN ANALYZE but I believe that we should split the work in 2 parts because a simple EXPLAIN would already provide relevant information.
To complete this work I believe that the following steps will be required:
- Rework and submit the CEP
- Add missing statistics
- Implements the logic behind the EXPLAIN statements