In this article
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Overview
Use this Snap to consolidate multiple input streams into a single output document, where each input stream is displayed as a label containing the records that were received by that input view.
Note that this Snap does not complete executing until the execution of all upstream Snaps is done.
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The Gate Snap always produces an output document, regardless of how many or if no input documents are received, even zero. In some Pipeline designs, this functionality can trigger an error message stating, mapped variables are missing, during validation. This error typically occurs when a downstream Snap expects a field based off an output document from the Gate Snap that is empty. To avoid thisprevent the error from occurring, you can prevent limit empty documents from being generated produced by the Gate Snap by inserting a Filter Snap directly after the Gate Snap it with the following expression in the Filter Expression
When you run the Pipeline after adding the Filter Snap with this expression, the Pipeline validates and executes successfully, and the error no longer occurs. |
Prerequisites
Because this Snap collects multiple input documents into a single output document, there are system memory limitations, and this Snap should not be used for massive data propagation. If large amounts of data are required, offload your data prior to Snap execution. Instead, write your data to a file or database; then, after Snap execution completes, you can use a Reader Snap (such as File Reader and S3 Reader) to read from the offloaded data source.
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