# Migrations - use them or not? **URL:** \ **Category:** Rails\ **Created:** [April 28, 2006, 8:19am UTC](https://www.ruby-forum.com/t/migrations-use-them-or-not/59056 "2006-04-28T08:19:51Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![splattael](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@splattael](https://www.ruby-forum.com/u/splattael)\ **Post date:** [April 28, 2006, 8:19am UTC](https://www.ruby-forum.com/t/migrations-use-them-or-not/59056/1 "2006-04-28T08:19:51Z")
Hello, As a rails newbie, i have stumbled upon some tutorials promoting migratons. I have thought, wow, cool and started using them right away. However, now that i am reading the RoR list on a daily basis, i have seen also mails ranging from ‘migrations are not always the best’ to ‘migrations are evil’ and even ‘i would not use migrations even if…’ So i would be interested in your oppinion - what are the downsides/possible problems/side effects (the pros are quite straightforward, so i am not asking for those) of using migrations? Thx, Peter ---
**Author:** ![splattael](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@splattael](https://www.ruby-forum.com/u/splattael)\ **Post date:** [April 28, 2006, 8:32am UTC](https://www.ruby-forum.com/t/migrations-use-them-or-not/59056/2 "2006-04-28T08:32:04Z")
The only problems I’ve ever had are: 1. PostgreSQL support is sometimes not 100%. This is in 1.0 of the framework - can’t remember the exact issue, but it was something to do with the :null =\> false thing not being supported properly. In any case it just meant that I write my non-trivial alter table statments manually. This might be fixed now - I haven’t checked. 2. Make sure you test going both up and down in migrations before you deploy, to make sure that the dropping of stuff works as you expected! That being said, the ability to do changes on the fly without having to muck about with manual change scripts is an awesome addition to the framework. Cheers, Dan ---
**Author:** ![splattael](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@splattael](https://www.ruby-forum.com/u/splattael)\ **Post date:** [April 28, 2006, 9:08am UTC](https://www.ruby-forum.com/t/migrations-use-them-or-not/59056/3 "2006-04-28T09:08:32Z")
Dan S. wrote: > That being said, the ability to do changes on the fly without having > to muck about with manual change scripts is an awesome addition to the > framework. > Well, i did not have exactly this on my mind (nevertheless thx for the > points, i am thinking about switching to postgre), since these can be > corrected manually - but there were some issues with database integrity > (FK contraints are not enforced or something like this) which can cause > serious problems (or at least the writer of the mail claimed - i could > not find the thread). ---
**Author:** ![splattael](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@splattael](https://www.ruby-forum.com/u/splattael)\ **Post date:** [April 28, 2006, 11:55am UTC](https://www.ruby-forum.com/t/migrations-use-them-or-not/59056/4 "2006-04-28T11:55:16Z")
On Friday 28 April 2006 08:05, Peter S. wrote: > Well, i did not have exactly this on my mind (nevertheless thx for the > points, i am thinking about switching to postgre), since these can be > corrected manually - but there were some issues with database integrity > (FK contraints are not enforced or something like this) which can cause > serious problems (or at least the writer of the mail claimed - i could > not find the thread). Peter All the stuff I’ve done with Rails was against Postgres and I haven’t seen any problems so far. I had to declare my foreign keys in SQL but the syntax is pretty simple. There is a plugin to make it easier at [http://wiki.rubyonrails.org/rails/pages/Foreign+Key+Schema+Dumper+Plugin](http://wiki.rubyonrails.org/rails/pages/Foreign+Key+Schema+Dumper+Plugin) but I haven’t used it myself. I would _definitely_ go with migrations. At my company, I spent two solid months designing a system that lets us upgrade any version of our main app to any more recent version. With migrations that is handled for you. You can work away without any fear that you will miss something when you go live with your changes. Another thing it enables you to do relatively easily is “continuous integration”. This is where you have your computer regularly get your latest changes and check they deploy to an existing version of the app. This isn’t important for small projects, but in a big team it makes you much more agile - you know within (say) an hour that someone has broke something and you can work on fixing it. So basically I say yes to migrations because they make life easier in the simple case and prepare you to scale up your work later (same applies to Postgres too!). Ashley ---
**Author:** ![splattael](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@splattael](https://www.ruby-forum.com/u/splattael)\ **Post date:** [April 28, 2006, 12:10pm UTC](https://www.ruby-forum.com/t/migrations-use-them-or-not/59056/5 "2006-04-28T12:10:30Z")
Ashley, Dan, Thx for your replies. It (hopefully) seems that the original author was just FUD-ing around and there is no catch behind migrations (or? 😉 Have a nice day, Peter ---
**Author:** ![splattael](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/s/858c86/32.png) [@splattael](https://www.ruby-forum.com/u/splattael)\ **Post date:** [April 28, 2006, 12:01pm UTC](https://www.ruby-forum.com/t/migrations-use-them-or-not/59056/6 "2006-04-28T12:01:23Z")
On 4/28/06, Peter S. [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid) wrote: > Well, i did not have exactly this on my mind (nevertheless thx for the > points, i am thinking about switching to postgre), since these can be > corrected manually - but there were some issues with database integrity > (FK contraints are not enforced or something like this) which can cause > serious problems (or at least the writer of the mail claimed - i could > not find the thread). Well, I don’t know about that… I mean for me I _always_ write FKs into migrations in an execute block because I am quite picky about that sort of stuff. In the end, all a migration is is a way to deploy changes to the DB - it’s just executing a chunk of ALTER TABLE or whatever, so as long as you can verify that it’s doing what you expect and putting the right FKs in, then it’s up to the DB to make sure that it happens. Might the original author have been having troubles with a MyISAM MySQL table? Perhaps the lack of transactions caused some problems? Anyway, I use migrations regularly on my sites and although I do test them with some vigour before I deploy them, I’ve yet to have a problem apart from those I mentioned. My 2c I guess. Cheers, Dan