Documentation Source Text

<title>SQLite: Most Widely Deployed SQL Database</title>

<h2>Most Widely Deployed Database</h2>

<p>We <em>believe</em> 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.</p>

<p>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.</p>

<h3>Estimates</h3>

<p>At the end of 2006, there were 100 million websites on the internet.
<a href="http://news.netcraft.com/archives/2006/11/01/november_2006_web_server_survey.html">[1]</a>
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.</p>

<p>Now let's consider where SQLite is used:</p>

<ul>
<li>125 million copies of Mozilla Firefox 
<a href="http://arstechnica.com/news.ars/post/20071202-mozilla-coo-over-125-million-people-use-firefox.html">[2]</a></li>
<li>20 million Mac computers, each of which contains multiple
copies of SQLite</li>
<li>20 million websites run PHP which has SQLite built in.  
<a href="http://www.php.net/usage.php">[3]</a>  We have no
way of estimating what fraction of those sites actively use
SQLite, but we think it is a significant fraction.<li>
<li>300 million downloads of the <a href="http://www.skype.com/">Skype</a>
client software and 100 million registered users
<a href="http://skypejournal.com/blog/archives/2006/04/how_many_users_does_skype_have_today.php">[4]</a>.  All recent versions of the Skype
client use SQLite internally.</li>
<li>20 million Symbian smartphones shipped in Q3 2007
<a href="http://www.symbian.com/news/pr/2007/pr20079552.html">[5]</a>
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.</li>
<li>Millions and millions of copies of
<a href="http://www.mcafee.com/">McAfee</a> anti-virus software all
use SQLite internally.</li>
<li>Millions of iPhones use SQLite</li>
<li>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.</li>
<li>There are perhaps millions of additional deployments of
SQLite that the SQLite developers do not know about.</li>
</ul>

<p>
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.
</p>