cl-migrations is a port of the database migrations feature of Ruby on Rails to Common Lisp. cl-migrations is intended to provide a simple way to version-control your database changes. As a web project grows, it's database will go through numerous structural changes. Even if the schema is available as an sql file for creating a database instance, it can quickly get out of sync with the actual database. Also, if things go wrong with a new version, there should be a proper way to disable new changes to database and bring it back to a previously known good position. cl-migrations creates a new file with a version number everytime a new database change to the database structure is to be made. It can revert, or forward to a given version number, or move the database to the latest version if no version number is given.
(asdf-install:install :cl-migrations)
(asdf-install:install "http://common-lisp.net/project/cl-migrations/cl-migrations-latest.tgz")
darcs get http://common-lisp.net/project/cl-migrations/darcs/cl-migrations
.migrate.conf
in your home directory (notice the dot in front). You can setup your database configuration something similar to this:
((:postgresql ("localhost" "clsql-test" "username" "password")) (:migration-dir ("/home/username/migrations/")))If you haven't done so already, load up
cl-migrations
:
(asdf:operate 'asdf:load-op :cl-migrations)
(require :cl-migrations)
(cl-migrations:generate "add-employees-table")
1-add-employees-table.lisp
in your migrations directory. You can populate the empty stub with something like this:
;; Auto-generated stub by cl-migrations. ;; 1-create-employees-table.lisp (:UP (("create table employees (id serial, name varchar(100))") ("create table products (id serial, name varchar(100))")) :DOWN (("drop table products") ("drop table employees")))
:up
will always contain the ddl which will create a table, add a column or other such modifications. :down
should contain the statements which reverts this change. Create a bunch of such files, and each will be given an increasing version number. So if you want to move your database to the latest version, you can simply do this:
(cl-migrations:migrate)
This will show some output on the sql being executed, how many migrations are done, etc. All these changes are done within a transaction, so you need not worry about half-done migrations in case of an sql error. Anyways, it is recommended that you run the sql statement first to check your errors before pasting it on to the :up>
or :down
elements.
Anytime you want to move to a specific version, you can supply the version number like this:
(cl-migrations:migrate :version 12)
cl-migrations
will then either migrate up, or down to reach the exact version number you have specified. when it is migrating up, only statements in :up
will be executed, and when it is migrating down, only statements in :down
will the executed. If you are facing any problems or need any help, please send a mail to the mailing lists specified below. Bug reports/patches are very much welcome.
cl-migrations
does not yet have the ability to generate a migration out of an existing database schema. This feature will be added soon.
cl-migrations depends on CLSQL for connecting to database, executing queries and making migrations work over different database engines. Many thanks to Kevin Rosenberg for maintaining this excellent piece of software.
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