— part of check-in
on branch trunk
— Trying to update and improve the "Architecture" document.
<h1 align=center>About SQLite</h1>
<div class="rightsidebar border2px">
<h4 align="center">Executive Summary</h4>
<li> <a href='lang.html'>Full-featured SQL</a>
<li> <a href='mostdeployed.html'>Billions and billions of deployments</a>
<li> <a href='onefile.html'>Single-file database</a>
<li> <a href='copyright.html'>Public domain source code</a>
<li> All source code in one file (<a href='amalgamation.html'>sqlite3.c</a>)
<li> <a href='footprint.html'>Small footprint</a>
<li> Max DB size: <a href='limits.html'>140 terabytes</a>
<li> Max row size: <a href='limits.html'>1 gigabyte</a>
<li> <a href='testing.html'>Aviation-grade quality and testing</a>
<li> <a href='zeroconf.html'>Zero-configuration</a>
<li> <a href='transactional.html'>ACID transactions, even after power loss</a>
<li> <a href='fileformat.html'>Stable, enduring file format</a>
<li> <a href='doclist.html'>Extensive, detailed documentation</a>
<li> <a href='lts.html'>Long-term support</a>
<p>SQLite is an in-process library that implements a
SQL database engine.
The code for SQLite is in the
<a href="copyright.html">public domain</a> and is thus free for
use for any purpose, commercial or private.
SQLite is the [most widely deployed] database in the world
with more applications than we can
count, including several <a href="famous.html">high-profile projects.</a></p>
<p>SQLite is an embedded SQL database engine.
Unlike most other SQL databases, SQLite does not have a separate
server process. SQLite reads and writes directly to ordinary disk
files. A complete SQL database with multiple tables, indices,
triggers, and views, is contained in a single disk file.
The database [file format] is cross-platform - you can freely copy a database
between 32-bit and 64-bit systems or between
[http://en.wikipedia.org/wiki/Endianness | big-endian] and
[http://en.wikipedia.org/wiki/Endianness | little-endian]
architectures. These features make SQLite a popular choice as
an [Application File Format].
Think of SQLite not as a replacement for
as a replacement for [http://man.he.net/man3/fopen|fopen()]</p>
<p>SQLite is a compact library.
With all features enabled, the [library size] can be less than 500KiB,
depending on the target platform and compiler optimization settings.
(64-bit code is larger. And some compiler optimizations
such as aggressive function inlining and loop unrolling can cause the
object code to be much larger.) If optional features are omitted, the
size of the SQLite library can be reduced below 300KiB. SQLite can also
be made to run in minimal stack space (4KiB) and
very little heap (100KiB), making SQLite a popular database engine
choice on memory constrained gadgets such as cellphones, PDAs, and MP3 players.
There is a tradeoff between memory usage and speed.
SQLite generally runs faster the more memory
you give it. Nevertheless, performance is usually quite good even
in low-memory environments.</p>
<a href="testing.html">very carefully tested</a> prior to every
release and has a reputation for being very reliable.
Most of the SQLite source code is devoted purely to testing and
verification. An automated test suite runs millions and millions of
test cases involving hundreds of millions of individual SQL statements
and achieves [test coverage | 100% branch test coverage].
SQLite responds gracefully to memory
allocation failures and disk I/O errors. Transactions are
even if interrupted by system crashes or power failures.
All of this is verified by
the automated tests using special test harnesses which simulate
Of course, even with all this testing, there are still bugs.
But unlike some similar projects (especially commercial competitors)
SQLite is open and honest about all bugs and provides
<a href="http://www.sqlite.org/src/rptview?rn=1">bugs lists</a> and
minute-by-minute <a href="http://www.sqlite.org/src/timeline">
chronologies</a> of code changes.</p>
<p>The SQLite code base is supported by an
<a href="crew.html">international team</a> of developers who work on
The developers continue to expand the capabilities of SQLite
and enhance its reliability and performance while maintaining
backwards compatibility with the
<a href="c3ref/intro.html">published interface spec</a>,
<a href="lang.html">SQL syntax</a>, and database [file format].
The source code is absolutely free to anybody who wants it,
but [professional support] is also available.</p>
<p>The SQLite project was started on
The future is always hard to predict, but the intent of the developers
is to support SQLite through the year 2050. Design decisions are made
with that objective in mind.</p>
<p>We the developers hope that you find SQLite useful and we
entreat you to use it well: to make good and beautiful products that
are fast, reliable, and simple to use. Seek forgiveness for yourself
as you forgive others. And just as you have received SQLite for free,
so also freely give, paying the debt forward.</p>