In the previous chapter, we discussed the querying side of Elasticsearch again. We learned how the Lucene TF/IDF algorithm works and how to use Elasticsearch scripting capabilities. We handled multilingual data and influenced document scores with boosts. We used synonyms to match words that have the same meaning and we used Elasticsearch Explain API to see how document scores were calculated. By the end of this chapter, you will have learned the following topics:
What are aggregations
How the Elasticsearch aggregation engine works
How to use metrics aggregations
How to use buckets aggregations
How to use pipeline aggregations