- CONFORMANCE WITH DBI SPECIFICATION
- DRIVER PRIVATE ATTRIBUTES
- DRIVER PRIVATE METHODS
- SEE ALSO
DBD::SQLite - Self Contained RDBMS in a DBI Driver
use DBI; my $dbh = DBI->connect("dbi:SQLite:dbname=dbfile","","");
SQLite is a public domain RDBMS database engine that you can find at http://www.hwaci.com/sw/sqlite/.
Rather than ask you to install SQLite first, because SQLite is public domain, DBD::SQLite includes the entire thing in the distribution. So in order to get a fast transaction capable RDBMS working for your perl project you simply have to install this module, and nothing else.
SQLite supports the following features:
- Implements a large subset of SQL92
See http://www.hwaci.com/sw/sqlite/lang.html for details.
- A complete DB in a single disk file
Everything for your database is stored in a single disk file, making it easier to move things around than with DBD::CSV.
- Atomic commit and rollback
Yes, DBD::SQLite is small and light, but it supports full transactions!
There's lots more to it, so please refer to the docs on the SQLite web page, listed above, for SQL details. Also refer to DBI for details on how to use DBI itself.
The API works like every DBI module does. Please see DBI for more details about core features.
Currently many statement attributes are not implemented or are limited by the typeless nature of the SQLite database.
Returns the version of the SQLite library which DBD::SQLite is using, e.g., "2.8.0".
Returns either "UTF-8" or "iso8859" to indicate how the SQLite library was compiled.
This method returns the last inserted rowid. If you specify an INTEGER PRIMARY KEY as the first column in your table, that is the column that is returned. Otherwise, it is the hidden ROWID column. See the sqlite docs for details.
To access the database from the command line, try using dbish which comes with the DBI module. Just type:
On the command line to access the file foo.db.
Alternatively you can install SQLite from the link above without conflicting with DBD::SQLite and use the supplied
sqlite command line tool.
SQLite is fast, very fast. I recently processed my 72MB log file with it, inserting the data (400,000+ rows) by using transactions and only committing every 1000 rows (otherwise the insertion is quite slow), and then performing queries on the data.
Queries like count(*) and avg(bytes) took fractions of a second to return, but what surprised me most of all was:
SELECT url, count(*) as count FROM access_log GROUP BY url ORDER BY count desc LIMIT 20
To discover the top 20 hit URLs on the site (http://axkit.org), and it returned within 2 seconds. I'm seriously considering switching my log analysis code to use this little speed demon!
Oh yeah, and that was with no indexes on the table, on a 400MHz PIII.
For best performance be sure to tune your hdparm settings if you are using linux. Also you might want to set:
PRAGMA default_synchronous = OFF
Which will prevent sqlite from doing fsync's when writing (which slows down non-transactional writes significantly) at the expense of some piece of mind. Also try playing with the cache_size pragma.
Likely to be many, please use http://rt.cpan.org/ for reporting bugs.
Matt Sergeant, email@example.com