DBIx::VersionedDDL - Upgrade and downgrade database schemas to a specified version.
Version 0.17
This module is a utility that can upgrade or downgrade a schema.
use DBIx::VersionedDDL; my $sv = DBIx::VersionedDDL->new( user => 'scott', pass => 'tiger', dsn => 'DBI:Oracle:orcl', ddl_dir => '/home/jdoe/ddl' ); # Migrate the schema to version 7. $sv->migrate(7);
or alternatively:
use DBIx::VersionedDDL; my $dbh = DBI->connect('DBI:Oracle:orcl', 'scott', 'tiger'); my $sv = DBIx::VersionedDDL->new( dbh => $dbh, ddl_dir => '/home/jdoe/ddl' ); # Migrate the schema to version 7. $sv->migrate(7);
DBIx::VersiondDDL installs a version table (schema_version) in the schema that stores the current version number of this schema. The developer or DBA who maintains the schema will place a series of upgrade and downgrade scripts in a ddl directory. The scripts will use the following naming convention:
+-----------------+-------------------+ | Upgrade Scripts | Downgrade Scripts | +-----------------+-------------------+ | upgrade1.sql | downgrade1.sql | | upgrade2.sql | downgrade2.sql | | upgrade3.sql | downgrade3.sql | | upgrade4.sql | downgrade4.sql | | .... | .... | +-----------------+-------------------+
Each downgrade script reverses the changes of the upgrade script. The scripts to run are determined by the value in the version table If the current schema is at version 5 and the administrator wishes to upgrade to version 10, upgrade scripts 6-10 would be run by the utility, and the version table entry will be incremented at each step.
If the administrator wishes to downgrade to version 6, the utility will run downgrade scripts 10-7.
This utility expects SQL statements to be separated by semi-colons by default, but an explicit separator can be specified.
DDL statements are not transactionally aware, so you can not roll back if there is an error in your DDL. You will need to manually resolve such errors.
Any error will be saved to the schema_version table. The version number is set to the script that was running when the error was encountered.
The database handle will autocommit any updates to the schema tables. If an active handle is supplied, it should not be shared with any external transactions. The best approach is to clone an active handle before passing it to the utility:
my $dbh = DBI->connect('DBI:Oracle:orcl', 'scott', 'tiger'); my $sv = DBIx::VersionedDDL->new( dbh => $dbh->clone, ddl_dir => '/home/jdoe/ddl' );
The schema_version table has three columns:
+---------+---------------------------------------------------+ | Column | Description | +---------+---------------------------------------------------+ | version | The current version of the schema | | status | The status of the script that updated the version | | | record. It will be either 'success' or 'error' | | message | Any message generated when an error occurs | +---------+---------------------------------------------------+
The following attributes can be supplied at creation time by passing values to the new method.
user. The database user account
pass. The user password.
dsn. The database DSN
ddl_dir. The directory that hosts the migration scripts
debug. Whether debug messages are shown
dbh. An active database handle. This can be used as an alternative to the user, pass and dsn parameters
script_processor. Optional. A plugin that processes the migration scripts. See "PROVIDING YOUR OWN PROCESSOR VIA A PLUGIN"
Migrate from the current schema version to the specified one:
$sv->migrate(7);
If a version is not provided, the schema will be upgraded (or downgraded!) to the maximum version specified by upgrade(n).sql:
$sv->migrate
Returns the message value in the schema_version table
You can supply your own functionality to parse migration scripts via a plugin. The plugin must contain a process_script method that takes a script name as an argument and returns an array of SQL statements. The name of your plugin can either be set in the environment variable SCRIPT_PROCESSOR or the script_processor attribute as part of the constructor. If your plugin is called DBIx::VersionedDDL::Plugin::MyProcessor, then SCRIPT_PROCESSOR should be set to MyProcessor.
For an example, refer to the source of DBIx::VersionedDDL::Plugin::DefaultScriptProcessor
Any attributes should be populated once the Versioned object is created:
my $sv = DBIx::VersionedDDL->new( user => 'scott', pass => 'tiger', dsn => 'DBI:Oracle:orcl', ddl_dir => '/home/jdoe/ddl' ); $sv->separator('/');
The definition of a schema can differ between database products. For Oracle a schema is a:
collection of database objects, including logical structures such as tables, views, sequences, stored procedures, synonyms, indexes, clusters, and database links. A schema has the name of the user who controls it.
In this context, the user parameter should be the owner of the schema. With other databases, such as MySQL, the schema is analogous to a database. The user parameter should be an account that has full privileges to the database so that it can apply the DDL and update the schema_version table.
migrate_schema is a script supplied with this distribution that supports the invocation of DBIx::VersionedDDL from the command line.
migrate_schema -user=scott -pass=tiger -dsn=DBI:Oracle:orcl \ -version=5 -ddl_dir=/my/ddl/dir
For more information:
man migrate_schema
Dan Horne, <dhorne at cpan.org>
<dhorne at cpan.org>
Plugin functionality added by Jiri Pavlovsky.
Please report any bugs or feature requests to bug-dbix-versionedddl at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=DBIx-VersionedDDL. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
bug-dbix-versionedddl at rt.cpan.org
You can find documentation for this module with the perldoc command.
perldoc DBIx::VersionedDDL
You can also look for information at:
RT: CPAN's request tracker
http://rt.cpan.org/NoAuth/Bugs.html?Dist=DBIx-VersionedDDL
AnnoCPAN: Annotated CPAN documentation
http://annocpan.org/dist/DBIx-VersionedDDL
CPAN Ratings
http://cpanratings.perl.org/d/DBIx-VersionedDDL
Search CPAN
http://search.cpan.org/dist/DBIx-VersionedDDL/
Copyright 2009-2010 Dan Horne.
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.
To install DBIx::VersionedDDL, copy and paste the appropriate command in to your terminal.
cpanm
cpanm DBIx::VersionedDDL
CPAN shell
perl -MCPAN -e shell install DBIx::VersionedDDL
For more information on module installation, please visit the detailed CPAN module installation guide.