title: System design for updating record in two system: parallel vs serial?
body: <p>We have a system that stores data in RDBMS. This data is being accessed by UI or APP. As the system is scaling, the latency of fetching this data is increasing.</p>
  <p>To scale the system and provided better search options we are planning to also store this data in Elastic Search or SOLR.
  New data will be inserted into the main system and will be sent to ES/SOLR via Kafka. App/UI will get this data from ES/SOLR.</p>
  <p>Now, App and UI can update this data. I want inputs on how to design this update flow.</p>
  <ul>
  <li><p>If an update is sent to the main system and then it is passed to ES via Kafka there might be a lag and UI/App may get stale records due to this.</p>
  </li>
  <li><p>If the update is sent parallelly to both the system, stale record issue will be resolved. But how to handle the exception when update on one of the systems fails and other passes?</p>
  </li>
  </ul>