title: Adding a custom column data type in Active Record
body: <p>On my local machine I develop my Rails application using MySQL, but on deployment I am using Heroku which uses PostgreSQL. I am in need of creating a new data type, specifically I wish to call it longtext, and it is going to need to map to separate column types in either database. </p>
  
  <p>I have been searching for this. My basic idea is that I am going to need to override some hash inside of the ActiveRecord::ConnectionAdapters::*SQL adapter(s) but I figured I would consult the wealth of knowledge here to see if this is a good approach (and, if possible, pointers on how to do it) or if there is a quick win another way.</p>
  
  <p>Right now the data type is "string" and I am getting failed inserts because the data type is too long. I want the same functionality on both MySQL and PgSQL, but it looks like there is no common data type that gives me an unlimited text blob column type? </p>
  
  <p>The idea is that I want to have this application working correctly (with migrations) for both database technologies. </p>
  
  <p>Much appreciated.</p>