Support bind joins in federation for exclusive groups

[aschwarte10]

Problem description

Currently bind joins are only supported for simple statement patterns.

Preferred solution

Support bind joins also for exclusive groups (i.e. a set of statement patterns with the same relevant source).

This is a natural enhancement to the current implementation and can be easily done with the VALUES clause implementation

Users of the federation will benefit in terms of performance for queries where there is a join of exclusive groups

Are you interested in contributing a solution yourself?

Yes

Alternatives you've considered

No response

Anything else?

No response

[aschwarte10]

This is not yet completed, reopening. Not a must for 5.1 though (so, if not ready in time, we can move to 5.2)