[Catalyst] DBIx::Migration released

[Sebastian Riedel]

You know the problem, you've got a Catalyst app installed on multiple  
servers, now you have to update them all.
Updating the Perl modules is quite easy, but the database schema  
changed! What now?

To prevent this problem completely there is now DBIx::Migration.

You can think of it as database schema revisions.
Everything starts at revision 1 for the first release, then you add a  
new revision for the following ones.
So you don't build a new schema, you extend/change the previous one.

The files are plain sql and can contain whatever your db supports,
only the filename is important, it has to end in _VERSION_TYPE.sql

Here's a simple example that supports up- and downgrades:


        # /Users/sri/myapp/db/sqlite/schema_1_up.sql
        CREATE TABLE foo (
            id INTEGER PRIMARY KEY,
            bar TEXT
        );

        # /Users/sri/myapp/db/sqlite/schema_1_down.sql
        DROP TABLE foo;

        # /Users/sri/myapp/db/sqlite/schema_2_up.sql
        CREATE TABLE bar (
            id INTEGER PRIMARY KEY,
            baz TEXT
        );

        # /Users/sri/myapp/db/sqlite/schema_2_down.sql
        DROP TABLE bar;


You don't have to use the module api directly, there is also a  
command line tool.

     # Initialize database with version 1
     dbix-migration.pl dbi:SQLite:/Users/sri/myapp/db/sqlite.db / 
Users/sri/myapp/db/sqlite 1

     # Upgrade database to version 2
     dbix-migration.pl dbi:SQLite:/Users/sri/myapp/db/sqlite.db / 
Users/sri/myapp/db/sqlite 2

     # Downgrade to version 0 (meaning uninstall)
     dbix-migration.pl dbi:SQLite:/Users/sri/myapp/db/sqlite.db / 
Users/sri/myapp/db/sqlite 0


Downgrades are just a goodie, you don't have to use them, but they  
could be quite useful during development.

--
sebastian