title: Salesforce get all objects that changed after some date
body: <p>I would like to keep an updated copy of some salesforce data in a database.</p>
  <p>e.g. a table with all contacts</p>
  <p>However, it is impractical to truncate the table and to query all data again on a frequent basis.</p>
  <p>Is there some way to only query changed contacts since the last sync?</p>
  <p>e.g. I would run an hourly job that gets all contacts that changed within the last hour.</p>
  <p>In addition, how could I deal with deleted contacts. I assume that if there is a way to get changed ones this might not include deletions.</p>