Databases
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    <p>A good way to do that is making a model for each database connection you need, and then make other models as subclasses of them. So, for example:</p> <ol> <li>Define all the needed connections in database.yml (per-environment)</li> </ol> <pre class="lang-none prettyprint-override"><code> # DB 1 development: adapter: mysql2 encoding: utf8 database: db_1 username: **** password: **** host: ******** pool: 5 ... # DB 2 db2_development: adapter: mysql2 encoding: utf8 database: db_2 username: **** password: **** host: ******** pool: 5 ... # Same for production (and/or other environments) production: ... db2_production: ... </code></pre> <ol> <li>Define a "master" model for each database, which inherits from <code>ActiveRecord::Base</code></li> </ol> <pre class="lang-rb prettyprint-override"><code> # DB1 class DB1 &lt; ActiveRecord::Base self.abstract_class = true end # DB2 class DB2 &lt; ActiveRecord::Base self.abstract_class = true establish_connection "db2_#{Rails.env}" end ... </code></pre> <ol> <li>Now define all the database-specific models as subclasses of the models defined above, in this way:</li> </ol> <pre class="lang-rb prettyprint-override"><code> # DB1 specific model class DB1_model &lt; DB1 # model logic here end # DB2 specific model class DB2_model &lt; DB2 # model logic here end ... </code></pre> <p>And you're good to go.</p> <p>In this way, you can connect to N databases in different environments (usually <code>development</code>, <code>staging</code>, <code>preprod</code> and <code>production</code>, but they may be different in your case).</p> <p>Also, remeber that Rails will manage a pool of SQL connections for each database. </p> <p>In the example above, Rails will open a maximum of <strong>5 connections</strong> for each database, so total will be <strong>10</strong> (for a <strong>single instance of your application</strong>). If you use Phusion Passenger or Unicorn, and spawn 8 application instances, total SQL connections will be (at maximum) 10*8 = 80.</p>
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    1. POusing activerecord with nested databases
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    1. USxmikex83
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    1. COThanks for the idea... I wound up just creating an instance method on each connection model which returns a connection using the Sequel gem . This way the databases do not need to be pre-defined in database.yml. But i'll accept your answer!
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    2. CO@user1609682 Thanks if you accept (I hope it helped you finding your own solution)!
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