ParallelismProvider (Flink : Table : Common 2.1.0 API)

All Known Subinterfaces:

InputFormatProvider, OutputFormatProvider, SinkV2Provider, SourceProvider, TransformationScanProvider
```
@PublicEvolving
public interface ParallelismProvider
```
Parallelism provider for other connector providers. It allows to express a custom parallelism for the connector runtime implementation. Otherwise, the parallelism is determined by the planner.

- Method Summary
  
  All Methods Instance Methods Default Methods
  Modifier and Type Method Description
  
  default Optional<Integer> getParallelism()
  Returns the parallelism for this instance.

- Method Detail
  - getParallelism
```
default Optional<Integer> getParallelism()
```
    Returns the parallelism for this instance.
    The parallelism denotes how many parallel instances of a source or sink will be spawned during the execution.
    Enforcing a different parallelism for sources/sinks might mess up the changelog if the output/input is not ChangelogMode.insertOnly(). Therefore, a primary key is required by which the output/input will be shuffled after/before records leave/enter the ScanTableSource.ScanRuntimeProvider/DynamicTableSink.SinkRuntimeProvider implementation.
    
    Returns:
    
    empty if the connector does not provide a custom parallelism, then the planner will decide the number of parallel instances by itself.