PostgreSQL has Foreign Data Wrapper feature and it is the powerful feature to access the distributed data across heterogenous data stores. FDW became writable at PostgreSQL 9.3 therefore PostgreSQL with FDW has potential to become distributed database supporting reads and writes. However one of the biggest missing piece is transaction management for distributed transactions. Currently atomicity and consistency of ACID properties are missing but are essential to achieve full ACID supported distributed transaction. Some proposals have been proposed but these are under discussion. This talks about the current status of FDW and problem regarding atomicity and isolation and introduce to the proposed solutions and other solutions employed by other distributed databases. Also I'll also explain the use cases like database sharding and federation.