Myracle opened a new pull request, #27577:
URL: https://github.com/apache/flink/pull/27577
## What is the purpose of the change
This pull request adds a new built-in function `REGEXP_SPLIT` to Flink SQL
and Table API, which splits a string by a regular expression pattern and
returns an array of substrings. This function is commonly available in other
SQL engines (e.g., Spark, Presto, Hive) and provides users with more powerful
string manipulation capabilities using regex patterns.
## Brief change log
- Added `REGEXP_SPLIT` function definition in `BuiltInFunctionDefinitions`
with proper input/output type strategies
- Implemented `RegexpSplitFunction` as a scalar function with regex pattern
caching for performance optimization
- Added `regexpSplit()` method to `BaseExpressions` for Table API support
- Added comprehensive test cases in `RegexpFunctionsITCase` covering various
scenarios including null handling, empty regex, invalid regex patterns, and
edge cases
## Verifying this change
This change added tests and can be verified as follows:
- Added integration tests in `RegexpFunctionsITCase` that cover:
- Basic regex split functionality (e.g., splitting by digit patterns
`[0-9]+`)
- Null input handling (both null string and null pattern)
- Empty regex pattern (split by each character)
- Multi-character delimiter regex patterns (e.g., `[,;|]`)
- Whitespace regex patterns (e.g., `\\s+`)
- No match scenarios (returns original string as single-element array)
- Invalid regex pattern handling (returns null)
- Input validation errors for non-string type inputs
- SQL signature validation errors
## 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)`: **yes** (`BaseExpressions` is `@PublicEvolving`, added
`regexpSplit()` method)
- The serializers: **no**
- The runtime per-record code paths (performance sensitive): **no** (new
function only, with pattern caching for optimization)
- 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? **yes**
- If yes, how is the feature documented? **JavaDocs** (function usage
examples are documented in `RegexpSplitFunction` class JavaDoc)
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