# Append Streams ## ![](/files/kW2dhdFNEcSwmqpOo85L) Append Streams ### Description The Append Streams transform reads the data from two transforms, only processing the second stream after the first one is finished. As always, the row layout for the input data coming from both transforms has to be identical: the same row lengths, the same data types, the same fields at the same field indexes in the row. **Important**: If you don’t care about the order in which the output rows occur, you can use any transform to create a union of 2 or more data streams. ### Supported Engines | Hop Engine | ✓ | | ---------- | ------------ | | Spark | X | | Flink | X | | Dataflow | X | ### Options | Option | Description | | -------------- | ----------------------------------------------------------------------------- | | Transform name | Name of the transform. Note: This name has to be unique in a single pipeline. | | Head hop | The name of the transform from which will be read the first stream. | | Tail hop | The name of the transform from which will be read the second stream. | --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://docs.primeur.com/data-shaper-1.21/knowing-the-data-shaper-designer/pipelines/transforms/append.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.