ElasticSearch Cookbook - Second Edition

Using a function score query

This kind of query is one of the most powerful queries available, because it allows extensive customization. The function score query allows you to define a function that controls the score of the documents that are returned by a query.

Generally, these functions are CPU-intensive and executing them on a large dataset requires a lot of memory, but computing them in a small subset can significantly improve the search quality.

These are the common scenarios used for this query:

• Creating a custom score function (for example with the decay function)
• Creating a custom boost factor, for example, based on another field (such as boosting a document by its distance from a point)
• Creating a custom filter score function, for example ...