The reason why I created three dedicated nodes is because of the following saying from this doc.
By default, every Elasticsearch node is configured to be a "master-eligible" data node, which means they store data (and perform resource-intensive operations) and have the potential to be elected as a master node. For a small cluster, this is usually fine; a large Elasticsearch cluster, however, should be configured with dedicated master nodes so that the master node's stability can't be compromised by intensive data node work.
I was afraid of what's going to happen when my app's traffic increases in the future so I decided to use dedicated master nodes as described from the start.
If I don't have to use dedicated master nodes, how should I handle the incoming sudden increase of data input?
Let's say I create three master-eligible data nodes as my new cluster and my app's searching data input soars at one point.
Do I need to add more master-eligible data nodes or just data nodes in this case?