Join GitHub today
GitHub is home to over 50 million developers working together to host and review code, manage projects, and build software together.
Sign upGitHub is where the world builds software
Millions of developers and companies build, ship, and maintain their software on GitHub — the largest and most advanced development platform in the world.
Ultimately this will create a unique column (or group of columns) in the database which may or may not be used as the principal end of a relationship. In other words, it's a way to make a non-primary key column have a unique constraint without explicitly specifying a unique index.
This is not technically blocked on #4073, but should probably not be implemented until #4073 is fixed.