title: How do I increase key length in MySQL 5.1?
body: <p>When running a Rails migration that creates an index, I get:</p>
  
  <pre><code>Mysql::Error: Specified key was too long; max key length is 1000 bytes: CREATE UNIQUE INDEX `index_matches_on_foo_and_bar_id_and_baz_id` ON `matches` (`foo`, `bar_id`, `baz_id`)
  </code></pre>
  
  <p>What MySQL variable do I need to set to increase this, and where do I set it so it affects all sessions, and not just the current client session?</p>