[weiqingy]

What is the purpose of the change

Function names are case-insensitive in SQL, but the UDF metric group (udf.<udf_name>) was named after the spelling used at the call site. Calling one function as myUdf(x) and MYUDF(x) in a query produced two groups, udf.myUdf and udf.MYUDF, each with part of the samples, and a dashboard built for one spelling missed the calls made with another. This pull request names the group after the normalized (lower-case) function name, so every spelling reports under one group. UDF metrics are new in 2.4.0, so changing the name now does not affect existing dashboards.

Brief change log

• Added BridgingFunctionGenUtil#udfMetricNameOf, which returns FunctionIdentifier#normalizeName of the function name for a function resolved by name, and the unchanged generated name for an inline function.
• Both places that produce a UDF metric name use it: BridgingSqlFunctionCallGen (sync scalar and table functions, async scalar functions) and the async table function correlate entry in BridgingFunctionGenUtil.
• An inline Table API function (for example call(new MyUdf(), $("x"))) is not looked up by name, so it cannot be split by spelling. It keeps its class-based name, since lower-casing it would only make the class harder to recognize.
• Only the metric name changes. Operator names, EXPLAIN output and plan digests are unaffected.
• The metrics docs (English and Chinese) state that the group name is the lower-case function name and describe the inline case.

Verifying this change

This change added tests and can be verified as follows:

• UdfMetricsITCase#testFunctionNameSpellingsShareOneLowerCaseGroup: mixedCaseUdf(id), MIXEDCASEUDF(id) registers exactly one group, udf.mixedcaseudf, which receives the samples of both calls.
• UdfMetricsITCase#testAsyncTableGroupNameIsLowerCase: an async table function called as ASYNCTABLEUDF(id) reports under udf.asynctableudf. This covers the second place that produces a metric name.
• UdfMetricsITCase#testInlineFunctionKeepsClassBasedGroupName: an inline Table API call keeps its class-based group name.
• Each new test fails when its part of the change is reverted. UdfMetricsITCase, AsyncCalcITCase and AsyncCorrelateITCase pass.

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changed class annotated with @Public(Evolving): no
• The serializers: no
• The runtime per-record code paths (performance sensitive): no
• Anything that affects deployment or recovery: JobManager (and its components), Checkpointing, Kubernetes/Yarn, ZooKeeper: no
• The S3 file system connector: no

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? docs

---

Was generative AI tooling used to co-author this PR?

• Yes (please specify the tool below)

Generated-by: Claude Code 2.1.322 (Claude Opus 5.5)

[flinkbot]

CI report:

• 356351e Azure: SUCCESS

Bot commands

The @flinkbot bot supports the following commands:

• @flinkbot run azure re-run the last Azure build