wbittles opened a new pull request, #28153:
URL: https://github.com/apache/flink/pull/28153
…time attribute type
Make WINDOW_START and WINDOW_END return the same type as the input time
attribute (TIMESTAMP or TIMESTAMP_LTZ) instead of always returning
TIMESTAMP(3). This ensures consistency with WINDOW_TIME behavior.
Changes:
- BuiltInFunctionDefinitions: Changed output type strategy from explicit
TIMESTAMP(3) to argument(0) for both WINDOW_START and WINDOW_END
- SqlWindowTableFunction: Use timeAttributeType for window_start and
window_end fields instead of hardcoded TIMESTAMP
- Updated test schemas to expect TIMESTAMP_LTZ(3) for all window properties
when using TIMESTAMP_LTZ input
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## Pull Request Template Answers for FLINK-36665
### What is the purpose of the change
This pull request fixes the return types of `WINDOW_START` and `WINDOW_END`
functions to match the input time attribute type (TIMESTAMP or TIMESTAMP_LTZ)
instead of always returning TIMESTAMP(3). This ensures type consistency across
all window property functions (`WINDOW_START`, `WINDOW_END`, and `WINDOW_TIME`).
### Brief change log
- Modified `BuiltInFunctionDefinitions.java`: Changed output type strategy
for `WINDOW_START` and `WINDOW_END` from `explicit(TIMESTAMP(3))` to
`argument(0)` to return the same type as the input time attribute
- Modified `SqlWindowTableFunction.java`: Updated `window_start` and
`window_end` field types to use plain TIMESTAMP (without time attribute
metadata) while preserving the precision from the input time attribute
- Updated `WindowTableFunctionTestPrograms.java`: Updated test schemas to
expect `TIMESTAMP_LTZ(3)` for all window properties when using `TIMESTAMP_LTZ`
input, and adjusted expected output values to include UTC timezone indicator
### Verifying this change
This change is already covered by existing tests, such as:
- `WindowTableFunctionTestPrograms` - Contains test programs that verify
window function behavior with different time attribute types
- The existing restore tests will need their execution plan JSON files
regenerated to reflect the new output types (this will be handled by CI or can
be done with a full clean build)
### 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** - `WINDOW_START` and `WINDOW_END` are public SQL
functions
- 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** - This is a bug fix
for type consistency
- If yes, how is the feature documented? **not applicable**
---
**Note:** This change modifies the return types of `WINDOW_START` and
`WINDOW_END`, which are `@PublicEvolving` functions. While this is technically
a breaking change, it fixes incorrect behavior where these functions didn't
respect the input time attribute type. Users relying on the old behavior
(always TIMESTAMP(3)) may need to adjust their code.
##### Was generative AI tooling used to co-author this PR?
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