title: Changing INT to BigInt
body: <p>I have a warehouse table with 16 tons of data in it. I have a few Integer columns in it. We have to cast these into BIGINT for every query we write, because the SUM is too large to fit in an INT.</p>
  
  <p>We now have a new datamart under development. So we thought, why not change all these columns into BIGINT and we have less to worry for the new set of queries.</p>
  
  <p>Since the data is already loaded, I figured I would use Management Studio and change the data type. But I first get a warning:</p>
  
  <p><code>Saving Definition Changes to tables with large amounts of data could take a considerable amount of time. While changes are being saved, table data will not be accessible.</code></p>
  
  <p>Then I get an error:</p>
  
  <p><code>Timeout expired.  The timeout period elapsed prior to completion of the operation or the server is not responding.</code></p>
  
  <p>How do I get around this?</p>