Storage Format

If you're working with Turso or need to understand how SQLite actually stores data on disk, this breaks down the file format internals. You get the page structure, B-tree organization, cell formats, overflow chains, and freelist management with actual byte offsets and diagrams. It points you to the relevant Rust files in Turso's codebase (btree.rs, pager.rs, sqlite3_ondisk.rs) and explains how table rows map to varints and serial types. Useful when you're debugging storage issues, optimizing page usage, or just curious why your database file is structured the way it is. The reference links to SQLite's official docs and Fly.io's internals writeup are solid next steps.

skills.sh installs: 1.3K
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last updated: Aug 21, 2026

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Install

$ npx -y skills add tursodatabase/turso --skill storage-format --agent claude-code

Installs into .claude/skills of the current project.

Files

Storage Format Guide

Database File Structure

┌─────────────────────────────┐
│ Page 1: Header + Schema     │  ← First 100 bytes = DB header
├─────────────────────────────┤
│ Page 2..N: B-tree pages     │  ← Tables and indexes
│            Overflow pages   │
│            Freelist pages   │
└─────────────────────────────┘

Page size: power of 2, 512-65536 bytes. Default 4096.

Database Header (First 100 Bytes)

Offset	Size	Field
0	16	Magic: `"SQLite format 3\0"`
16	2	Page size (big-endian)
18	1	Write format version (1=rollback, 2=WAL)
19	1	Read format version
24	4	Change counter
28	4	Database size in pages
32	4	First freelist trunk page
36	4	Total freelist pages
40	4	Schema cookie
56	4	Text encoding (1=UTF8, 2=UTF16LE, 3=UTF16BE)