Postgres-XL is an open source fork of PostgreSQL as a scalable distributed database cluster.
The origins of
Postgres-XL lie in a product first developed in 2012 by StormDB built on top of the existing Postgres-XC codebase.
Postgres-XL itself was released as an open source project under that name in 2014 following StormDB's acquisition by TransLattice.
An official-looking repository can be found on GitHub but that has not been updated since 2015.