PLEASE NOTE:
We are working on updating this book for the latest version. Some content might be out of date.
We are working on updating this book for the latest version. Some content might be out of date.
In Life Inside a Cluster, we introduced the shard, and described it as a low-level worker unit. But what exactly is a shard and how does it work? In this chapter, we answer these questions:
- Why is search near real-time?
- Why are document CRUD (create-read-update-delete) operations real-time?
- How does Elasticsearch ensure that the changes you make are durable, that they won’t be lost if there is a power failure?
- Why does deleting documents not free up space immediately?
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What do the
refresh,flush, andoptimizeAPIs do, and when should you use them?
The easiest way to understand how a shard functions today is to start with a history lesson. We will look at the problems that needed to be solved in order to provide a distributed durable data store with near real-time search and analytics.