twalthr opened a new pull request #14329:
URL: https://github.com/apache/flink/pull/14329
## What is the purpose of the change
This updates the `LookupTableSource` interface to the new type system.
```
* <p>By default, input and output data types are automatically extracted
using reflection. This includes
* the generic argument {@code T} of the class for determining an output
data type. Input arguments are
* derived from one or more {@code eval()} methods. If the reflective
information is not sufficient, it
* can be supported and enriched with {@link DataTypeHint} and {@link
FunctionHint} annotations. See
* {@link TableFunction} for more examples how to annotate an implementation
class.
*
* <p>Note: Currently, asynchronous table functions are only supported as
the runtime implementation
* of {@link LookupTableSource}s for performing temporal joins. By default,
input and output {@link DataType}s
* of {@link AsyncTableFunction} are derived similar to other {@link
UserDefinedFunction}s using the
* logic above. However, for convenience, in a {@link LookupTableSource} the
output type can simply be
* a {@link Row} or {@link RowData} in which case the input and output types
are derived from the
* table's schema with default conversion.
```
## Brief change log
It updates the code base to use a unified extraction logic for all kinds of
functions.
## Verifying this change
This change is already covered by existing tests, such as `LookupJoinITCase`
and `AsyncLookupJoinITCase`.
This change added tests and can be verified as follows:
`FunctionITCase.testLookupTableFunction`
## 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
- 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/Mesos, 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
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