elasticsearch/docs/reference/scripting-languages/painless/painless-metric-agg-reduce-context.md

mapped_pages	products
https://www.elastic.co/guide/en/elasticsearch/painless/current/painless-metric-agg-reduce-context.html	id painless

Metric aggregation reduce context [painless-metric-agg-reduce-context]

Use a Painless script to reduce values to produce the result of a scripted metric aggregation. A reduce script is run once on the coordinating node following a combine script (or a map script if no combine script is specified) and is optional as part of a full metric aggregation.

Variables

params (Map, read-only)

User-defined parameters passed in as part of the query.

states (Map)

Map with values available from the prior combine script (or a map script if no combine script is specified).

Return

List, Map, String, or primitive

A value used as the result.

API

The standard Painless API is available.