9.9. Summary

You should now have a better understanding of how Elasticsearch clusters are formed and how they’re made of multiple nodes, each containing a number of indices, which in turn are made up of a number of shards. Here are some of the other things we talked about in this chapter:

What happens when nodes are added to an Elasticsearch cluster

How master nodes are elected

Removing and decommissioning nodes

Using the _cat API to understand your cluster

Over-sharding and how it can be applied to plan for future growth of a cluster

How to use aliases and routing for cluster flexibility and scaling

In chapter 10 we’ll continue talking about scaling from the perspective of improving performance in your Elasticsearch cluster.