title: Join or storing directly
body: <p>I have a table A which contains entries I am regularly processing and storing the result in table B. Now I want to determine for each entry in A its latest processing date in B.</p>
  
  <p>My current implementation is joining both tables and retrieving the latest date. However an alternative, maybe less flexible, approach would be to simply store the date in table A directly.</p>
  
  <p>I can think of pros and cons for both cases (performance, scalability, ....), but didnt have such a case yet and would like to see whether someone here on stackoverflow had a similar situation and has a recommendation for either one for a specific reason.</p>
  
  <p>Below a quick schema design.</p>
  
  <pre><code>Table A
  id, some-data, [possibly-here-last-process-date]
  
  Table B
  fk-for-A, data, date
  </code></pre>
  
  <p>Thanks</p>