Use different mongodb instances in mongoid

14 Jan 2011

By default, we save all the collections in one mongodb instance, or replicate/shard all of them into different mongodb instances. But what if saving a special collection into one mongodb instance, and the other collections into the other mongodb instance?

This is what I need to do with a mongoid project several weeks before. In common we just define a mongodb instance in the config/mongoid.yml, yep, you can define only one instance for one environment just like activerecord, the define the different mongodb instance in model.

class Ad
  include Mongoid::Document

  collection.master =, AD_DB_PORT).db(AD_DB_NAME),

change the AD_DB_HOST, AD_DB_PORT, AD_DB_NAME and AD_COLLECTION_NAME with your mongodb configuration, the following is my configuration,

AD_DB_HOST => 'localhost'
AD_DB_PORT => 27018
AD_DB_NAME => 'ad_developmet'

and it would be better move these configurations into a config file.

Now when saving or reading the ads collection, it uses localhost:27018/ad_development, and the other collections use localhost:27017/project_development.


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