Elasticsearch filter nested objects

1. How do I filter nested objects in Elasticsearch?
2. How does filter work in Elasticsearch?

How do I filter nested objects in Elasticsearch?

If so, you can filter nested objects by nested query and inner_hits option. If you mean filtering field of nested objects, you can use _source option for inner_hits.

How does filter work in Elasticsearch?

Frequently used filters will be cached automatically by Elasticsearch, to speed up performance. Filter context is in effect whenever a query clause is passed to a filter parameter, such as the filter or must_not parameters in the bool query, the filter parameter in the constant_score query, or the filter aggregation.