SQLite — Trivia & Interesting Facts¶
Surprising, historical, and little-known facts about SQLite.
SQLite is the most deployed database engine in the world¶
SQLite is embedded in every Android phone, every iPhone, every Mac, every Windows 10+ machine, every major web browser, and most TV sets. D. Richard Hipp estimates there are over 1 trillion SQLite databases in active use worldwide, making it by far the most widely deployed database engine — and likely the most widely deployed software component of any kind.
SQLite was originally designed for a U.S. Navy destroyer¶
D. Richard Hipp created SQLite in 2000 while working on a contract for the U.S. Navy's guided missile destroyer program (DDG-79, USS Oscar Austin). The existing software used Informix, which required a DBA to configure. Hipp wanted a database that required zero administration and could survive power failures on a warship. SQLite was the result.
SQLite's test suite has over 100 million lines of test code¶
SQLite's test harness contains approximately 150 million lines of test code — over 1,000 times more test code than the approximately 150,000 lines of source code. This extraordinary test coverage includes modified condition/decision coverage (MC/DC), which is a standard required for DO-178B aircraft certification. SQLite achieves 100% branch coverage.
The entire SQLite database is a single file¶
A complete SQLite database — tables, indexes, schema, data — is contained in a single cross-platform file. The file format is documented so thoroughly that the Library of Congress recommends SQLite as a storage format for long-term data preservation. The file format has been stable since version 3.0 (2004) with a guarantee of backward compatibility through at least 2050.
SQLite is in the public domain, not open-source¶
Technically, SQLite is not "open-source" because it uses no license at all — it is released into the public domain. This is a stronger grant than any open-source license because there are zero restrictions on use. For jurisdictions that do not recognize public domain dedications, Hipp sells "Warranty of Title" certificates for a fee.
SQLite processes more SQL statements per day than all other database engines combined¶
Because SQLite is embedded in billions of devices and applications, it processes more SQL statements daily than PostgreSQL, MySQL, Oracle, and SQL Server combined. Every time a browser stores a cookie, an app saves a preference, or a phone logs a contact, SQLite is likely executing the SQL behind it.
WAL mode was added in 2010 and transformed SQLite for concurrent access¶
Before Write-Ahead Logging mode was added in version 3.7.0 (2010), SQLite used a rollback journal that required exclusive locks for writes, preventing all concurrent readers. WAL mode allows concurrent reads during writes, dramatically improving throughput for multi-threaded applications. This single feature expanded SQLite's use cases from single-user to moderate-concurrency server applications.
SQLite can handle databases up to 281 terabytes¶
The maximum SQLite database size is 281 terabytes (2^48 bytes minus 1), limited by the page count maximum of 4,294,967,294 pages at the maximum page size of 65,536 bytes. In practice, few SQLite databases exceed a few gigabytes, but the theoretical limit is far larger than most people assume for an "embedded" database.
Richard Hipp maintains SQLite almost single-handedly¶
While SQLite has occasional contributors, D. Richard Hipp has written the vast majority of the code and serves as the BDFL (Benevolent Dictator For Life). He has maintained the project for over 25 years through his company Hwaci. SQLite's development is funded by a consortium of companies (including Adobe, Bloomberg, and Mozilla) that pay annual membership fees.