title: Case insensitive index in postgres, handles case sensitive queries?
body: <p>If I change a regular unique index on <code>users.email</code> to a case insensitive one by creating this index:</p>
  
  <pre><code>CREATE UNIQUE INDEX user_email_ci_idx ON users ((lower(email)));
  </code></pre>
  
  <p>Any reason not to drop the prior case sensitive index?</p>
  
  <p>I would guess that Postgres will switch to the new index, and performance would be equivalent?</p>