elastic/elasticsearch

Allow Bucket Script aggregation to reference on string results

Closed

#36,642 opened on Dec 14, 2018

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 (9 comments) (4 reactions) (0 assignees)Java (25,882 forks)batch import
:Analytics/Aggregations>enhancementTeam:Analyticshelp wanted

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Description

Currently bucket script aggregations allows only numbers to be referenced on:

      "some-stringified-metric":{  
          "bucket_script":{  
            "buckets_path":{  
              "a":"path>of>nested>metrics>agg_that_returns_a_string.value"
            },
            "script":{  
              "source":"params.a"
            }
          }
        },

You will get: "buckets_path must reference either a number value or a single value numeric metric aggregation, got: java.lang.String"

Result of the agg is just a string, not a list of object, or something complex. Why plain single strings are so offended that they can not be returned as a result?

Contributor guide

Research direction
Investigate the bucket script aggregation code in the Elasticsearch source, likely in the 'aggs' package. The validation in the bucket script parsing logic restricts referenced metrics to numeric types. Understand why string results are rejected and consider allowing them when the result is a plain string. Review existing tests for bucket script to ensure backward compatibility.
Tech stack
java
Domain
backenddata
Issue type
Feature
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
3-5 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Elasticsearch aggregation basicsJava developmentKnowledge of bucket scriptSource code navigation
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25