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## Most Widely Deployed Database

We believe that there are more copies of SQLite in use around the world than any other SQL database engine, and possibly all other database engines combined. We cannot be certain of this since we have no way of measuring either the number of SQLite deployments nor the number of deployments of other databases. But we beleave the claim is defensible.

The belief that SQLite is the most widely deployed SQL database engine stems from its use as an embedded database. Other database engines, such as MySQL, PostgreSQL, or Oracle, are typically found one to a server. And usually a single server can serve multiple users. With SQLite, on the other hand, a single user will typically have exclusive use of multiple copies of SQLite. SQLite is used on servers, but it is also used on desktop PC, and in cellphones, and PDAs, and MP3-players, and set-top boxes.

### Estimates

At the end of 2006, there were 100 million websites on the internet. [1] Let us use that number as a proxy for the number of deployed SQL database engines other than SQLite. Not every website runs an SQL database engine. Larger websites run multiple database engines. But the vast majority of smaller websites (the long tail) share a database engine with several other websites, if they use database engine at all Hopefully these two factors cancel each other out and give 100 million as a reasonable estimate for the number of non-SQLite SQL database engines currently deployed.

Now let's consider where SQLite is used:

- 125 million copies of Mozilla Firefox [2]
- 20 million Mac computers, each of which contains multiple copies of SQLite
- 20 million websites run PHP which has SQLite built in. [3] We have no way of estimating what fraction of those sites actively use SQLite, but we think it is a significant fraction.
- 300 million downloads of the Skype client software and 100 million registered users [4]. All recent versions of the Skype client use SQLite internally.
- 20 million Symbian smartphones shipped in Q3 2007 [5] Newer versions of the SymbianOS have SQLite built in. It is unclear exactly how many Symbian phones actually contain SQLite, so we will use a single quarter's sales as a lower bound.
- Millions and millions of copies of McAfee anti-virus software all use SQLite internally.
- Millions of iPhones use SQLite
- Millions and millions of other cellphones from other manufactures other Symbian and the iPhone use SQLite. This has not been publicly acknowledged by the manufactures but it is known to the SQLite developers.
- There are perhaps millions of additional deployments of SQLite that the SQLite developers do not know about.

By these estimates, we see 200 or 300 million SQLite deployments and about 100 million deployments of other SQL database engines. These estimates are obviously very rough and may be off significantly. But there is a wide margin. So the SQLite developers think it is likely that SQLite is the most widely deployed SQL database engine in the world.

This page last modified 2007/12/20 21:10:17 UTC