== Auto Migration 
Performs database migration based on differences between a schema.rb and the target database among other tasks. Look into Commands for a full list.

Auto migration features:

- Minimal dependencies. No Ruby on Rails needed.
- Easy source control. Add schema.rb to the repoistory and can be used in deployments.

This was created because while I'm not having Rails on the server, I'll have Ruby due to a Chef Client. I also did not want to create or version many migration scripts.

This should also interface well with a Capistrano Auto Migration recipe on top for ease of deployment.

= Basic dependencies (Ubuntu. Likely Debian too)	
This is the interface to databases		
	sudo gem install activerecord --no-rdoc --no-ri 	
We want to be able to run rake commands, so thus need these both (especially for ubuntu).		
	sudo gem install rake --no-rdoc --no-ri 	
	ln -s /var/lib/gems/1.8/bin/rake /usr/local/bin/rake	
= Install
	sudo apt-get install git-core -y	
	git clone git://github.com/joakal/auto_migrations.git ~/auto_migrations	
Need to add the cloned repo'd files to a git repo		
	cd ~/auto_migrations	
	git init	
	git add .
Build the gem and then install it		
	gem build ~/auto_migrations/gem/auto_migrations.gemspec	
	sudo gem install --local ~/auto_migrations/gem/auto_migrations-1.0.20111031.gem --no-rdoc --no-ri	
Move the relevant automigration files to any directory. Lets assume your directory is helloworld in your user directory:		
	cp ~/auto_migrations/Rakefile -f ~/helloworld/automigrations/Rakefile	
	cp ~/auto_migrations/db/schema.rb -f ~/helloworld/automigrations/db/schema.rb	
	cp ~/auto_migrations/config/index.html -f ~/helloworld/automigrations/config/index.html	
Now there needs to be a specified database.yml in the config folder. Lets assume it's postgresql you're using then do the following:		
	echo "adapter: postgresql" | tee -a ~/helloworld/automigrations/config/database.yml
	echo "database: helloworld_development" | tee -a ~/helloworld/automigrations/config/database.yml	
	echo "username: deploys" | tee -a ~/helloworld/automigrations/config/database.yml	
	echo "password: hunter2" | tee -a ~/helloworld/automigrations/config/database.yml	
	echo "host: localhost" | tee -a ~/helloworld/automigrations/config/database.yml	
The database.yml takes the ruby database format that's available at many other places.		
		
You can remove ~/auto_migrations folder to clean up a bit.
	
= Usage		
	rake {command}	
		
	Note: Must be in the directory of Rakefile.	
= Commands		
	db:auto:migrate	
		Uses db/schema.rb to compare against the target database to perform migrations based on assumptions. 
		tables can be added and deleted.
		columns can be added, deleted and changed depending on database.
		indexs can be added and deleted.
		
		DESTRUCTIVE OPERATION.
	db:auto:migrate_safely	
		Uses db/schema.rb to compare against the target database to perform migrations safely based on assumptions. 
		tables can be added.
		columns can be added.
		indexs can be added.
	db:schema:to_migration	
		Create a migration script from db/schema.rb.
	db:schema:to_migration_with_reset	
		Create a migration script from db/schema.rb that includes resetting versioning.
	db:schema:dump	
		Creates the db/schema.rb based on the target database.
	db:schema:load	
		Drops everything in the database and loads the db/schema.rb to the target database to create from scratch.
		
		DESTRUCTIVE OPERATION.
		
= Tutorial – Single Computer		
Do the install above. Lets assume the application name is helloworld of course.
		
Also mentioned, it's postgresql being used. So lets keep using it for this tutorial.
Install postgresql if you haven't already
	sudo apt-get install postgresql -y
Using the postgres library (or use whichever you prefer).
	sudo apt-get install libpq-dev -y
	sudo gem install pg -v '0.11.0' --no-rdoc --no-ri
Superuser deploys!
	sudo -u postgres createuser -s deploys
Security protip: Create a user for the database or sections of the database instead of full access to all the databases.
Annoying ident: In postgres directory, modify pg_hba.conf to trust local connections. (Then restart postgresql)

Create your own database (psql refuses to work unless you have your own database apparently)
	sudo -u postgres psql -c "CREATE USER deploys WITH CREATEDB LOGIN ENCRYPTED PASSWORD 'hunter2'"
Now create the database
	psql -U deploys -c 'CREATE DATABASE helloworld_development'

In your database, create a table called "users" with columns “username” => string, “age” => integer		
	psql -U deploys -d 'helloworld_development' -c 'CREATE TABLE users (username varchar, age integer)'	
		
Next add some data!		
	psql -U deploys -d "helloworld_development" -c "INSERT INTO users (username, age) VALUES ('Joakal', 400)"	
	psql -U deploys -d "helloworld_development" -c "INSERT INTO users (username, age) VALUES ('torrancew', 500)"	
	psql -U deploys -d "helloworld_development" -c "INSERT INTO users (username, age) VALUES ('Harzilein', 500)"	
	psql -U deploys -d "helloworld_development" -c "INSERT INTO users (username, age) VALUES ('Ruby', 4)"
See the data:
	psql -U deploys -d "helloworld_development" -c "SELECT * FROM users"	
Add an index on username
	psql -U deploys -d "helloworld_development" -c "CREATE UNIQUE INDEX username_idx ON users (username); "
		
Add a composite index on age + username	
	psql -U deploys -d "helloworld_development" -c "CREATE UNIQUE INDEX combo_idx ON users (username, age); "
		
This is the table so far:
	psql -U deploys -d "helloworld_development" -c "\d users"

Lets dump it to ~/helloworld/automigrations/db/schema.rb
	cd ~/helloworld/automigrations
	rake db:schema:dump

Open up ~/helloworld/db/schema.rb. Pretty sweet eh? Add a new table just below that other table. Ignore that other table and indexes.
	  create_table "product", :force => true do |t|
	    t.datetime "created_at"
	    t.string   "brand"
	    t.string   "name"
	    t.integer   "quantity"
	  end
Now load it!
	cd ~/helloworld
	rake db:auto:migrate_safely

Look up the table.
	psql -d "helloworld_development" -c "\d product"

It loads the new table and columns, neat eh?