PostgreSQL: Documentation: 18: Chapter 66. Database Physical Storage

September 25, 2025: PostgreSQL 18 Released!

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Chapter 66. Database Physical Storage
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Chapter 66. Database Physical Storage

Table of Contents

66.1. Database File Layout

66.2. TOAST

66.2.1. Out-of-Line, On-Disk TOAST Storage
66.2.2. Out-of-Line, In-Memory TOAST Storage

66.3. Free Space Map

66.4. Visibility Map

66.5. The Initialization Fork

66.6. Database Page Layout

66.6.1. Table Row Layout

66.7. Heap-Only Tuples (HOT)

This chapter provides an overview of the physical storage format used by PostgreSQL databases.

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65.6. Hash Indexes	Home	66.1. Database File Layout

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