Tool for managing and executing your database migrations.

gem install db-migrate

If you are going to use for example Postgres with migrate, make sure that you have Postgresql server running. migrate is using lazy installation of database specific gems, so it will install pg or mysql2 (if they are not installed already) gem when you choose database type. It is recommended that you install them manually (officialy-supported-versions).

It saves metadata about your migrations to database and uses that metadata for executing and creating new migrations.

It supports multiple databases and multiple languages for executing migrations.

• PostgreSQL
• MySQL

• SQL
• Ruby
• Python
• Javascript (Node.js)
• Go

• ENV variables support in configuration file

Commands:
  migrate init               # initialize tables and create config file if necessary
  migrate new [DESCRIPTION]  # generate files for new migration
  migrate up                 # Upgrade database schema
  migrate down               # Downgrade database schema
  migrate list               # Show list of all migrations
  migrate delete [VERSION]   # Will delete migration data
  migrate version            # Show current version
  migrate help [COMMAND]     # Describe available commands or one specific
Options:
  -r, [--root=ROOT]      # Sepcify migration root directory, where config file is located
                         # Default: .
  -c, [--config=CONFIG]  # Specify custom configuration file name
                         # Default: migrate.conf

First thing you have to do is to make initial configuration with migrate init command.

migrate will look for file migrate.conf. If file exists, it will make configuration based on file contents. Example configuration file:

# pg or mysql
storage=pg
# can be one of: sql, ruby, javascript, go, python
lang=sql
# db host
host=localhost
# db port
port=5432
# name of database to use
database=mydb
# db user
user=myuser
# db password
password=${SOME_ENV_VARIABLE}
# name of table where version information will be stored
version_info=version_info_table_name
# name of table where version number will be stored
version_number=version_number_table_name

If configuration file does not exist, it will run interactive configuration file creation process. You will answer few questions about your database, and migrate will create configuration file for you.

This command will generate migration scripts for you based on your prefered language.

You will get new directory in format vXXX-YYYY, where XXX is version number, and YYY is short description you provide. Inside generated directory there will be two files. up.LANG and down.LANG, where LANG is language you use for writing migration scripts.

When you are done with writing your up and down migration script, you can execute migrate up to run up migration script for new version.

Running up without arguments will move for one version up. You can also execute multiple migrations in single call by providing --to n argument, where n is highest version where you want to navigate.

If you want to run all remaining available migrations, you can pass -a flag to up command, and migrate will run all available migrations.

You can also use migrate down to go one version back. down comand also accepts --to n argument, but in this case n is lowest version where you want to navigate.

If you are asking yourself about current version, use migrate version to find out current version.

If you don't need some migration, use migrate delete n to remove version n.

You can see list of your migrations by running migrate list. This command also provides some additional options for filtering results.

• do ruby magic
• write tests!
• send pull request

MIT