.SQLITE

Introduction

SQLite is a complete SQL database held in a single file, read and written by a small library built into the program that uses it. D. Richard Hipp released it in 2000. It ships inside every major web browser and phone operating system, so SQLite files are among the most common files in the world.

This is the format of SQLite version 3. It has been stable and backwards compatible since SQLite 3.0 in 2004. Programs name these files freely: .sqlite, .sqlite3 and .db are common, and many applications use their own extension. See all the SQLite versions.

Structure

The file is divided into pages of equal size, a power of two from 512 to 65,536 bytes. Page 1 starts with a 100-byte header, beginning with the 16 bytes SQLite format 3 and a zero byte. All numbers in the header are big-endian.

Every table and every index is a B-tree of pages. The rest of page 1 is the root of the schema table, sqlite_schema, which lists every table, index and view with its SQL and the page number of its root. Unused pages sit on a free list. While a database is open in write-ahead logging mode, changes may also be held in the -wal and -shm files beside it.

Telling SQLite files apart

Read the first 16 bytes. SQLite format 3 followed by a zero byte means this format. A file that starts with ** This file contains an SQLite is an SQLite 2 database, which SQLite 3 cannot open.

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