title: Postgres: Optimizing querying by datetime
body: <p>I have a table that has a datetime field "updated_at". A lot of my queries will be querying on this field using range queries such as rows that have updated_at > a certain date.</p>
  
  <p>I already added an index to updated_at, but most of my queries are still very slow, even when I had a limit to the number of rows return.</p>
  
  <p>What else can I do to optimize queries that query on datetime fields?</p>