Datamapper with a Mysql Master/Slave

I cant seem to find an开发者_StackOverflow社区y info on how to use datamapper talk to a mysql master/slave setup. I'm running rails3 with dm-mysql-adapter

You can use DataMapper's Multiple Data Store feature for this:

DataMapper.setup(:default, 'mysql://master-host/mydb')
DataMapper.setup(:slave, 'mysql://slave-host/mydb')

Now, whenever you'd like to read from the slave, use:

DataMapper.repository(:slave) do
  Person.first
end

Unfortunately, it doesn't look like you can do transparent read-from-slave write-to-master:

[...] This will use your connection to the :external data-store and the first Person it finds. Later, when you call .save on that person, it'll get saved back to the :external data-store; An object is aware of what context it came from and should be saved back to.

So, if you try to save a person you retrieved from the slave, it will try to store it back to the slave database when modified.

This may be what you are looking for...

https://github.com/d11wtq/dm-master-slave-adapter

you don't have to do this in your application, but may Mysql handle that itself. That way, you can take all the benefits of load-balancing and high-availability with automatic master fail-over with you. I'd highly recommend this setup over a manual, application based load-balancing, as you should leave the persistence-layer out of the business logic provided by your application. This brings the already written advantages and makes your application more scalable and maintainable due to a better separation of concerns.

Have a look at the Mysql NDB documentation for the concepts and this tutorial for a quickstart in Mysql Clustering.

1) You have to instal the adapter.

2) Add requires require 'rubygems' require 'data_mapper' 3) Config my sql

DataMapper.setup(:default, 'mysql://localhost/the_database_name')

or

DataMapper.mysql(:host xxxx, :user xxxx, :password xxxx, :database xxxx)

4) Create you model objects for example:

class Post
  include DataMapper::Resource

  property :id,         Serial    # An auto-increment integer key
  property :title,      String    # A varchar type string, for short strings
  property :body,       Text      # A text block, for longer string data.
  property :created_at, DateTime  # A DateTime, for any date you might like.
end

If you have any doubt you could check this link: http://datamapper.org/getting-started