title: Should you ever duplicate data?
body: <p>This is a very general question about database design in regards to products that have multiple running campaigns that may share data sets. I'm trying to understand concepts on why I should and should not do something like this. </p>
  
  <p>I was thinking of having a raw set of data, and then copying a part of that set over to the campaign so that the campaign will always have historical data. For example, even if the raw data updates, the campaign's data wouldn't change. However, the issue is that there is just so much duplication and I'm not sure if that's a very good design. Any insight appreciated.</p>