org.apache.beam.sdk.schemas.io

Interface PushdownProjector<InputT extends PInput>

@Experimental
public interface PushdownProjector<InputT extends PInput>

Factory for creating a PTransform that can execute a projection.

Typically this interface will be implemented by a reader PTransform that is capable of pushing down projection to an external source. For example, SchemaIO.buildReader() may return a PushdownProjector to which a projection may be applied later.

Method Summary

Modifier and Type	Method and Description
boolean	supportsFieldReordering() Returns true if this instance can do a projection that returns fields in a different order than the projection's inputs.
PTransform<InputT,PCollection<Row>>	withProjectionPushdown(FieldAccessDescriptor fieldAccessDescriptor) Returns a PTransform that will execute the projection specified by the FieldAccessDescriptor.

Method Detail

withProjectionPushdown

PTransform<InputT,PCollection<Row>> withProjectionPushdown(FieldAccessDescriptor fieldAccessDescriptor)

Returns a PTransform that will execute the projection specified by the FieldAccessDescriptor.

supportsFieldReordering

boolean supportsFieldReordering()

Returns true if this instance can do a projection that returns fields in a different order than the projection's inputs.