Fix minimum required bucket count for exponential histogram merging #133711
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
elasticsearchmachine
added
needs:triage
JonasKunz
added
Team:StorageEngine
:StorageEngine/Mapping
elasticsearchmachine
added
needs:risk
|
Pinging @elastic/es-storage-engine (Team:StorageEngine) |
felixbarny
reviewed
Aug 28, 2025
...stogram/src/main/java/org/elasticsearch/exponentialhistogram/ExponentialHistogramMerger.java
Outdated
Show resolved
Hide resolved
felixbarny
approved these changes
Aug 29, 2025
kkrik-es
added
>test
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
The exponential histogram merging algorithm previously did not verify the desired target bucket count for the result of the merge operation.
Because due to how exponentialhistograms work, at least for buckets are requried to represent every possible distribution:
(-Inf, -1),(-1, 0),(0, 1)and(1, +Inf).This was uncovered by a randomized test from a different PR:
https://buildkite.com/elastic/elasticsearch-pull-request/builds/88511#0198f05a-75bd-4e01-82fb-96ff2133a74e
This PR adds a fix and a reproducer test.