Yevhenii Kurtov (6) [Avatar] Offline

3 years is a lot of time and I wonder how much changed from the time of publishing and what is not covered in the book?

radu.gheorghe (55) [Avatar] Offline

I think it's relevant if you want to understand how Elasticsearch works. It's not that relevant if you want to solve a specific problem, as it might be missing essential features that were added in the meantime. For example, index sorting, index rollover or the reindex API.

The essential parts, like generic field types (although some naming has changed), indexing, field data and doc values, aggregations, caches and other core things are definitely still valid.