Harco de Hilster <Harco.de.Hilster@ATConsultancy.nl> writes:
> What is the definition of a merge-joinable condition?
Equality on a sortable datatype.
> Can I create an type/operator that compares both records that is
> considered merge-joinable?
I think you could do something involving a time interval datatype that
considers "overlap" as equality and does something reasonable for
sorting non-overlapping intervals. It'd take a bit of work ... nothing
particularly difficult, just tedious. The "seg" datatype in contrib/
might serve as a prototype.
regards, tom lane