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Prior to release 10, PostgreSQL used a three-part numbering series, meaning that the feature set and compatibility related to the first two numbers, while maintenance releases were denoted by the third number. For instance, version 9.4 contains more additional features and compatibility changes when compared to version 9.3; version 9.4.0 was the initial release of 9.4, and version 9.4.1 was a later maintenance release.

The release support policy for PostgreSQL is available at http://www.postgresql.org/support/versioning/. This article explains that each release will be supported for a period of five years. Since we release one major version per year, this means five major releases.

Support for all releases up to and including 9.3, ended in September 2018. So, by the time you're reading this book, only PostgreSQL 9.4 and higher versions will be supported. The earlier versions are still robust, though many performance and enterprise features are missing from those releases. The future end-of-support dates are as follows: