opensearch-project/OpenSearch

[Enhancement] Histogram aggregation should initialize Ranges lazily

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#18,241 opened on May 8, 2025

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 (13 comments) (0 reactions) (1 assignee)Java (1,505 forks)batch import
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Description

Is your feature request related to a problem? Please describe

Currently, optimized histogram aggregation using multi range traversal initialized Ranges with all buckets eagerly. While for individual request, memory implications are small, it can starting adding up across all requests on a node.

Describe the solution you'd like

Given we process buckets one at a time, they can be initialized lazily avoiding unnecessary memory allocations. This should also allow to raise the number of buckets limit from 3k to 10k or more

Related component

No response

Describe alternatives you've considered

No response

Additional context

No response

Contributor guide

Research direction
Examine the histogram aggregation code to identify where ranges are eagerly initialized. Implement lazy initialization to allocate ranges on demand per bucket, reducing memory overhead and potentially increasing bucket limits.
Tech stack
java
Domain
backend
Issue type
Performance
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
Half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
Active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
Clear
Prerequisites
Java
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
60