---
title: "Database Physical Storage"
id: storage
pg_version: "20devel"
---

<a id="storage"></a>

# Database Physical Storage

## Table of Contents

- [66.1. Database File Layout](storage-file-layout.md)
- [66.2. TOAST](storage-toast.md)
  - [66.2.1. Out-of-Line, On-Disk TOAST Storage](storage-toast.md#storage-toast-ondisk)
  - [66.2.2. Out-of-Line, In-Memory TOAST Storage](storage-toast.md#storage-toast-inmemory)
- [66.3. Free Space Map](storage-fsm.md)
- [66.4. Visibility Map](storage-vm.md)
- [66.5. The Initialization Fork](storage-init.md)
- [66.6. Database Page Layout](storage-page-layout.md)
  - [66.6.1. Table Row Layout](storage-page-layout.md#storage-tuple-layout)
- [66.7. Heap-Only Tuples (HOT)](storage-hot.md)

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