The Internals of PostgreSQL is a detailed technical documentation resource that explains how PostgreSQL’s internal mechanisms function, according to the site at interdb.jp. The documentation was first published on September 26, 2015, and celebrates its 11th anniversary in 2026.
The resource covers versions 19-beta and earlier, and is organized into 12 chapters addressing different aspects of the database system. According to the documentation, PostgreSQL is described as a well-designed, open-source multi-purpose relational database system used widely throughout the world. The documentation aims to explain how each subsystem works and provide a comprehensive picture of PostgreSQL’s architecture.
Key topics covered include database cluster structure and tables (Chapter 1), process and memory architecture (Chapter 2), and query processing (Chapter 3). The documentation also addresses Foreign Data Wrappers (Chapter 4), concurrency control (Chapter 5), VACUUM processing (Chapter 6), and Heap Only Tuple operations and index-only scans (Chapter 7).
Additional chapters cover the buffer manager (Chapter 8), Write-Ahead Logging or WAL (Chapter 9), online backup and point-in-time recovery mechanisms (Chapter 10), and streaming replication (Chapter 11). Chapter 12 addresses logical replication and is listed as a beta version.
Recent updates include the publication of Section 8.5 on “Asynchronous I/O in PostgreSQL” in June 2026, and the beta release of Chapter 12 on logical replication in May 2026. The documentation notes that understanding PostgreSQL’s internal mechanisms is crucial for both administration and integration using the system, despite the system’s size and complexity making it difficult to comprehend fully.
The documentation was authored by Hironobu SUZUKI, a software programmer and engineer with a master’s degree in information engineering. SUZUKI has published seven books in database and system integration fields, including four PostgreSQL books and three MySQL books. A Chinese version of the documentation was published in June 2019. The documentation is copyrighted, though educational institutions are permitted to use it freely.
Key facts
- The documentation was first published September 26, 2015 and reached its 11th anniversary in 2026
- Coverage includes PostgreSQL versions 19-beta and earlier
- The guide comprises 12 chapters addressing different database system components
- Recent additions include Chapter 12 on logical replication (beta) and Section 8.5 on asynchronous I/O
- Author Hironobu SUZUKI has published 7 books on databases and system integration, including a Chinese translation published in 2019