Perl DBI driver with a self-contained RDBMS

 DBD::SQLite is a Perl DBI driver with a self-contained relational database
 management system. It embeds a small and fast embedded SQL database engine
 called SQLite (see sqlite3) into a DBI driver. It is useful if you want a
 relational database for your project, but don't want to install a large
 RDBMS system like MySQL or PostgreSQL.
 .
 SQLite supports the following features:
 .
  * Implements a large subset of SQL92 (<URL:http://www.sqlite.org/lang.html>)
  * 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
 .
 The engine is very fast, but for updates/inserts/dml it does perform a global
 lock on the entire database. This, obviously, might not be good for multiple
 user systems. The database also appears to be significantly faster if your
 transactions are coarse.