Pg Xl

PostgresXL is a horizontally scalable SQL database cluster

  • It is equipped to handle write-intensive workloads that depend on atomic transactions which are potentially distributed
    • OLTP
  • PostgresXL allows you to either partition tables across multiple nodes, or replicate them.
    • Partitioning (or distributing) tables allows for write scalability across multiple nodes as well as massively parallel processing (MPP) for Big Data type of workloads.
      • MPP is using many computers to perform a set of coordinated computations in parallel

Components of Postgres-XL

Global Transaction Monitor

  • ensures cluster-wide transaction consistency
    • responsible for issuing transaction ids and snapshots as part of its Multi-version Concurrency Control.


  • manages the user sessions and interacts with GTM and the data nodes
    • parses and plans queries, and sends down a serialized global plan to each of the components involved in a statement.

Data node

  • where the actual data is stored.
    • The distribution of the data can be configured by the DBA.
  • warm standbys of the data nodes can be configured to be failover-ready.