Rels currently complect identity and value, and are not first class. This enhancement provides a single-arity relation as a first class persistent value. Equality (and hash code) is defined in terms of the ITableRel protocol, leaving the door open for alternative implementations.

The implementation provide in the attached patch is a hair faster than Rels in the single index case. The query strategy used in the multiple index case may or may not be faster than the one employed by Rels depending on the data. This could easily be made configurable, if desired.