On 8th of May, Andres Freund committed patch: Add support for INSERT ... ON CONFLICT DO NOTHING/UPDATE. The newly added ON CONFLICT clause allows to specify an alternative to raising a unique or exclusion constraint violation error when inserting. ON CONFLICT refers to constraints ...

On 7th of December, Tom Lane committed patch by Jeff Davis that adds general exclusion constraints: Log Message: ----------- Add exclusion constraints, which generalize the concept of uniqueness to support any indexable commutative operator, not just equality. Two rows violate the exclusion constraint if ...