This directory contains the source code distribution of the PostgreSQL database management system.

PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings.

Copyright and license information can be found in the file COPYRIGHT.

General documentation about this version of PostgreSQL can be found at https://www.postgresql.org/docs/19/. In particular, information about building PostgreSQL from the source code can be found at https://www.postgresql.org/docs/19/installation.html.

The latest version of this software, and related software, may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.

This source tree implements Chronos interval-based database branching. See BRANCHING.md for setup and everyday use. See CHRONOS_VERSIONING.md for the versioning algorithm and PostgreSQL implementation details. A Docker-compatible build is described in docker/chronos/README.md.

The Chronos paper describes the interval-based versioning algorithm and its cross-store implementation. This repository applies the algorithm within PostgreSQL for single-database branching.

@misc{zhou2026chronos,
  title         = {{Chronos}: Efficient Bolt-on Branching Across Data Stores for Stateful Agentic Applications},
  author        = {Xinjing Zhou and Jason Mohoney and Samuel Madden and Michael Stonebraker and Lei Cao},
  year          = {2026},
  eprint        = {2609.14889},
  archivePrefix = {arXiv},
  primaryClass  = {cs.DB},
  url           = {https://arxiv.org/abs/2609.14889}
}