Forks

A fork is an independent development of a software project based on another project. There are more than 20 PostgreSQL forks; PostgreSQL-extensible APIs make PostgreSQL a great candidate for forking. Over the years, many groups forked PostgreSQL and contributed their findings to PostgreSQL.

HadoopDB is a hybrid between the PostgreSQL RDBMS and MapReduce technologies that targets analytical workload. The following is a list of popular PostgreSQL forks:

• Greenplum: A DBMS for OLAP applications built on the foundation of PostgreSQL. It utilizes the shared-nothing and massively parallel processing (MPP) architectures. It's used as a data warehouse and for analytical workloads. Greenplum started as proprietary software and open sourced in 2015.
• EnterpriseDB Advanced Server: A proprietary DBMS that provides Oracle with the capability to cap the Oracle fees.
  
• Vertica: A column-oriented database system that was started by Michael Stonebraker in 2005, and was acquired by HP in 2011. Vertica reused the SQL parser, semantic analyzer, and standard SQL rewrites from the PostgreSQL implementation.
• Netezza: A popular data-warehouse appliance solution.
• Amazon Redshift: A popular data-warehouse management system based on PostgreSQL 8.0.2. It is mainly designed for OLAP applications.
• PostgreSQL extensions: Several companies developed a data framework as an extension to PostgreSQL, such as Citus, PipelineDB, and TimeScaleDB. Developing a framework as extensions enables the developers to benefit from new PostgreSQL releases and features. Citus extends PostgreSQL and provides scaling capabilities for PostgreSQL. PipelineDB is a PostgreSQL extension for time-series aggregation, and real-time reporting. TimeScaleDB is a scalable data store for time-series data.