simple-db-migrate “quick” documentation
simple-db-migrate is damn simple. The best way to understand how it works is installing and using it.
You can install it by typing:$ sudo easy_install simple-db-migrate
There are more detailed instructions and information about installing directly from source on the project website.
After installing, for usage tips type:$ db-migrate —help
Understanding how it works
The first thing you’ll need is a migration file. There are some example migration files on the “example” directory. The migration files have the following format:SQL_UP = """ CREATE TABLE aleatory ( id int(11) NOT NULL auto_increment, name varchar(255) default NULL, PRIMARY KEY (id) ); """ SQL_DOWN = """ DROP TABLE aleatory; """
… where SQL_UP and SQL_DOWN are two strings that contains respectively the SQL statements to upgrade and downgrade the database schema.
You can use db-migrate to create the migrations by typing:$ db-migrate —create create_table_users
The file names need to respect the format “YYYYMMDDHHMMSS_migration_description.migration”. simple-db-migrate uses the YYYYMMDDHHMMSS information to track the database schema version and to decide the order of execution of the scripts. simple-db-migrate will go through all .migration files in your directory and execute all of them in their creation (date) order.
Second, you have to configure access to your MySQL database so simple-db-migrate can execute DDL. Just create a file named “simple-db-migrate.conf” located in your migrations dir, with the following content (there is also an example on the “example” directory):DATABASE_HOST = “localhost” DATABASE_USER = “root” DATABASE_PASSWORD = "" DATABASE_NAME = “migration_example” DATABASE_MIGRATIONS_DIR = “.”
- The MIGRATIONS_DIR directive is the relative path to the migrations directory from the location of this file.
You don’t need to create the database. simple-db-migrate will create it for you.
After this two things you are ready to go. Just navigate to your migrations directory and type:$ db-migrate
If you don’t want to navigate to the directory, you can specify it path instead. In this case you will also need to specify the path to the config file. Note that this also makes it possible to use any name you like for the config file:$ db-migrate —dir=path/to/migrations/dir —config=path/to/file.conf
Migrating to a specific version
If you want you can migrate your database schema to specific version by informing the —migration (or -m) parameter. The version id is the YYYYMMDDHHMMSS identifier used at the migration file:$ db-migrate —migration=20090227000129
If you don’t specify any version, simple-db-migrate will migrate the schema to the latest version available on the migrations directory.
Roadmap, bug reporting and feature requests
For detailed info about future versions, bug reporting and feature requests, go to the project’s ticket system at Lighthouse.
Mail me at “guilherme.chapiewski at gmail.com” for further questions.