# Package com.google.cloud.dataflow.sdk.transforms.join

Defines the `CoGroupByKey` transform for joining multiple PCollections.

See: Description

Class Summary
CoGbkResult: A row result of a `CoGroupByKey`.
CoGbkResult.CoGbkResultCoder: A `Coder` for `CoGbkResult`s.
CoGbkResultSchema: A schema for the results of a `CoGroupByKey`.
CoGroupByKey<K>: A `PTransform` that performs a `CoGroupByKey` on a tuple of tables.
KeyedPCollectionTuple<K>: An immutable tuple of keyed `PCollections` with key type K.
KeyedPCollectionTuple.TaggedKeyedPCollection<K,V>: A utility class to help ensure coherence of tag and input PCollection types.
RawUnionValue: This corresponds to an integer union tag and value.

## Package com.google.cloud.dataflow.sdk.transforms.join Description

Defines the `CoGroupByKey` transform for joining multiple PCollections.