NAME
ORLite::Migrate - Extremely light weight SQLite-specific schema
migration
SYNOPSIS
# Build your ORM class using a patch timeline
# stored in the shared files directory.
use ORLite::Migrate {
create => 1,
file => 'sqlite.db',
timeline => File::Spec->catdir(
File::ShareDir::module_dir('My::Module'), 'patches',
),
user_version => 8,
};
# migrate-1.pl - A trivial schema patch
#!/usr/bin/perl
use strict;
use DBI ();
# Locate the SQLite database
my $file = <STDIN>;
chomp($file);
unless ( -f $file and -w $file ) {
die "SQLite file $file does not exist";
}
# Connect to the SQLite database
my $dbh = DBI->connect("dbi:SQLite(RaiseError=>1):$file");
unless ( $dbh ) {
die "Failed to connect to $file";
}
$dbh->do( <<'END_SQL' );
create table foo (
id integer not null primary key,
name varchar(32) not null
)
END_SQL
DESCRIPTION
THIS CODE IS EXPERIMENTAL AND SUBJECT TO CHANGE WITHOUT NOTICE
YOU HAVE BEEN WARNED!
SQLite is a light weight single file SQL database that provides an
excellent platform for embedded storage of structured data.
ORLite is a light weight single class Object-Relational Mapper (ORM)
system specifically designed for (and limited to only) work with SQLite.
ORLite::Migrate is a light weight single class Database Schema Migration
enhancement for ORLite.
It provides a simple implementation of schema versioning within the
SQLite database using the built-in "user_version" pragma (which is set
to zero by default).
When setting up the ORM class, an additional "timeline" parameter is
provided, which should point to a directory containing standalone
migration scripts.
These patch scripts are named in the form migrate-$version.pl, where
$version is the schema version to migrate to. A typical timeline
directory will look something like the following.
migrate-01.pl
migrate-02.pl
migrate-03.pl
migrate-04.pl
migrate-05.pl
migrate-06.pl
migrate-07.pl
migrate-08.pl
migrate-09.pl
migrate-10.pl
ORLite::Migrate formulates a migration plan, it will start with the
current database "user_version", and then step forwards looking for a
migration script that has the version "user_version + 1".
It will continue stepping forwards until it runs out of patches to
execute.
If ORLite::Migrate is also invoked with a "user_version" param (to
ensure the schema matches the code correctly) the plan will be checked
in advance to ensure that the migration will end at the value specified
by the "user_version" param.
Because the migration plan can be calculated from any arbitrary starting
version, it is possible for any user of an older application version to
install the most current version of an application and be ugraded
safely.
The recommended location to store the migration timeline is a shared
files directory, locatable using one of the functions from
File::ShareDir.
SUPPORT
Bugs should be reported via the CPAN bug tracker at
<
http://rt.cpan.org/NoAuth/ReportBug.html?Queue=ORLite-Migrate>
For other issues, contact the author.
AUTHOR
Adam Kennedy <
[email protected]>
COPYRIGHT
Copyright 2009 - 2010 Adam Kennedy.
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
The full text of the license can be found in the LICENSE file included
with this module.
