ESQL: GroupedTopNOperator benchmark

[ivancea]

Operator added in #143476

Similar structure as TopNBenchmark, with similar parameters to keep the comparison consistent.

Benchmark results for some similar cases (Compared with TopN):

TopNBenchmark
Benchmark                                (data)  (sortedInput)  (topCount)  Mode  Cnt   Score   Error  Units
TopNBenchmark.run  longs_asc_and_bytes_refs_asc          false          10  avgt    7  56.292 ± 0.922  ns/op
TopNBenchmark.run  longs_asc_and_bytes_refs_asc          false        1000  avgt    7  54.866 ± 1.091  ns/op

GroupedTopNBenchmark
Benchmark                                       (data)  (groupCount)  (groupKeys)  (topCount)  Mode  Cnt    Score    Error  Units
GroupedTopNBenchmark.run  longs_asc_and_bytes_refs_asc             1        longs          10  avgt    7  103.886 ± 10.041  ns/op
GroupedTopNBenchmark.run  longs_asc_and_bytes_refs_asc             1        longs        1000  avgt    7  103.321 ±  5.021  ns/op
GroupedTopNBenchmark.run  longs_asc_and_bytes_refs_asc           100        longs          10  avgt    7  118.975 ±  7.685  ns/op
GroupedTopNBenchmark.run  longs_asc_and_bytes_refs_asc           100        longs        1000  avgt    7  205.589 ± 30.058  ns/op

[Copilot]

Pull request overview

Adds a new JMH benchmark for the ESQL GroupedTopNOperator (LIMIT BY) following the existing TopNBenchmark structure, plus a small test harness to run the benchmark’s selfTest() under the test suite.

Changes:

• Introduce GroupedTopNBenchmark JMH benchmark with parameters for sort keys, group keys, and sizes.
• Add GroupedTopNBenchmarkTests to execute GroupedTopNBenchmark.selfTest().

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 2 comments.

File	Description
benchmarks/src/main/java/org/elasticsearch/benchmark/_nightly/esql/GroupedTopNBenchmark.java	Implements the grouped top-N benchmark and its self-test.
benchmarks/src/test/java/org/elasticsearch/benchmark/_nightly/esql/GroupedTopNBenchmarkTests.java	Adds an ESTestCase wrapper to run the benchmark self-test.

---

💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.

You can also share your feedback on Copilot code review. Take the survey.

[elasticsearchmachine]

Pinging @elastic/es-analytical-engine (Team:Analytics)

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: fdc7eea7-1551-4e27-a2b7-2221471410e7

📥 Commits

Reviewing files that changed from the base of the PR and between 498aa28 and b92407e.

📒 Files selected for processing (3)

• benchmarks/src/main/java/org/elasticsearch/benchmark/_nightly/esql/GroupedTopNBenchmark.java
• benchmarks/src/main/java/org/elasticsearch/benchmark/_nightly/esql/TopNBenchmark.java
• benchmarks/src/test/java/org/elasticsearch/benchmark/_nightly/esql/GroupedTopNBenchmarkTests.java

---

📝 Walkthrough

Walkthrough

This change introduces a new JMH benchmark class GroupedTopNBenchmark for testing Elasticsearch ESQL grouped top-N operations. The benchmark features parametrized configurations for data shape, top-N count, group count, and group key types, with helper methods for constructing operators, pages, and blocks. An existing TopNBenchmark class is updated to improve resource management using try-finally blocks and a shared constant for data parsing. A corresponding test class GroupedTopNBenchmarkTests is added to validate the new benchmark via its self-test method.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

• 🛠️ Update Documentation: Commit on current branch
• 🛠️ Update Documentation: Create PR

📝 Coding Plan

• ❌ Error while generating coding plan for human review comments - (🔄 Check again to try again)

---

_{Comment @coderabbitai help to get the list of available commands and usage tips.}

[coderabbitai]

Planning has been disabled by your administrator. You can enable it by adding the following to your .coderabbit.yaml:

issue_enrichment:
  planning:
    enabled: true

[nik9000]

Looks good to me. Let's get it in.

It isn't a surprise that it's slower to topn with groups. It's slower to agg with groups too.

[nik9000]

And we can and will optimize this more as time goes on.