Comments on: Dump an Existing Database Schema Into a Ruby On Rails Migration Ready Format

By: Generate Rails Migrations from your PostgreSQL or MySQL database « The Irish Penguin

Wed, 25 Nov 2009 21:47:34 +0000

[...] to Justin Ball on this Nobody Listens Anyway blog at Dump an Existing Database Schema Into a Ruby On Rails Migration Ready Format for the basis of this tip. Sometimes somebody [...]

By: jbasdf

jbasdf — Tue, 22 Sep 2009 21:41:06 +0000

I don't know that I'm so cool, but there are some cool guys around the net. Rails Guides is a great place for the big stuff - http://guides.rubyonrails.org/ and Rails inside highlights some cool stuff http://www.railsinside.com/

By: billitch

billitch — Tue, 22 Sep 2009 13:47:49 +0000

Thank you !

This is typically the obvious part of the Ruby On Rails framework that is not formally documented, but rather given drop by drop by cool people like you.

Why isn't there a wiki where we would all write a more comprehensive documentation for Rails in a single place ?

By: Bob Campbell

Bob Campbell — Wed, 03 Jun 2009 20:30:21 +0000

Nope! Which of course I discovered after posting.

I found the yaml_db which is what I want.

So maybe what’s needed is a mix of the two? Like, ‘rake db:backup’ and ‘rake db:restore’? Hmm…

By: Justin Ball

Justin Ball — Wed, 03 Jun 2009 19:12:45 +0000

I’m not sure if rake db:schema:dump will dump the data. I think it just dumps the db structure in which case it wouldn’t make a very good backup. You probably could take the rake task and modify it to dump the data in which case you would have an easy backup.

By: Bob Campbell

Bob Campbell — Wed, 03 Jun 2009 18:59:50 +0000

The default schema.rb file has this comment:

# Note that this schema.rb definition is the authoritative source for your database schema. If you need
# to create the application database on another system, you should be using db:schema:load, not running
# all the migrations from scratch.

Would this imply that you could rake db:schema:dump your development database, copy the file to your production database and rake db:schema:load (with RAILS_ENV=production) and it would populate the database with everything?

Seems like this might be a decent way to create a backup of the database, too, that would be faster to regenerate, ala’ cronjob:
rake db:schema:dump
cp /site/db/schema.db /backup/site/db/schema.rb.$datestamp
In case of disaster, copy back and
rake db:schema:load

Thoughts?

By: Justin Ball

Justin Ball — Mon, 20 Apr 2009 16:13:51 +0000

No doubt the technique is a bit tricky, but you should only be doing this on a dev machine with a backup copy of a database so that if something goes bad you can just start over.

By: Dietrich Speer

Dietrich Speer — Fri, 17 Apr 2009 18:29:03 +0000

D-A-N-G-E-R-O-U-S
I ran into some weird problems on a new site under development and decided to restart by creating a new database using db:schema:dump. So I create the new site using rake, change the db config to the old database and run it. Next is the new migration. Then I should have changed the db config to the new database, which I forgot. The result after db: migrate is a nice clean database schema with all the data gone.
D-A-N-G-E-R-O-U-S

By: glennswest

glennswest — Fri, 09 Jan 2009 02:28:03 +0000

This is great idea. Been doing migrations and database conversions for a while, and never thought to “hack” it at this level.
Simple “DRY” and nice.

By: Justin Ball

Justin Ball — Fri, 12 Dec 2008 04:35:06 +0000

Glad I could help. Hopefully it all goes smoothly.