In this chapter, we primarily focused on improving the performance and scaling the clusters. We started with the concepts of validating queries to find out the bugs before actually executing them and then saw how to take advantage of query profiling to learn all the granular details of the overall query execution time. Next, we learned about hot threads to identify the issues in the cluster and then did a detailed coverage of how to scale the Elasticsearch clusters under different loads and requirements. We finally, ended the chapter after discussing two awesome features; index shrinking and rollover which are introduced in Elasticsearch version 5.0.
In the next chapter, we are going to learn about Elasticsearch plugins' development by showing and describing in-depth, how to write your own custom plugins in Java.