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Supported Aggregation Pipeline Stages

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  • Supported Aggregation Pipeline Stages

Atlas Stream Processing extends the aggregation pipeline with stages for processing continuous data streams. These stages combine with existing aggregation stages built in to the default mongod process, enabling you to perform many of the same operations on continuous data as you can perform on data-at-rest. An Atlas Stream Processing pipeline definition cannot exceed 16 MB.

The following table lists the aggregation pipeline stages unique to Atlas Stream Processing and those which exist in modified form in Atlas Stream Processing.

Note

For details on a specific operator, including syntax and examples, click on the link to the operator's reference page.

Aggregation Pipeline Stage
Purpose
$source
Specifies a streaming data source to consume messages from.
Validates the documents of a stream against a user-defined schema.

Performs a left outer join to a specified collection to filter in documents from the "joined" collection for processing.

This version of the existing $lookup stage requires that you specify a Atlas collection in the Connection Registry as the value for the from field.

Assigns documents from a stream to windows with user-defined durations and intervals between start times.
Assigns documents from a stream to non-overlapping, continuous windows with user-defined durations.
Specifies a stream or time series collection in the connection registry to emit messages to.
A version of the existing $merge stage where the value of the connectionName field must always be the name of a remote collection in the Connection Registry.

You can also use the following stages supported by all mongod processes in your streaming data pipelines:

Aggregation Pipeline Stage
Use Conditions
Anywhere
Anywhere
Anywhere
Anywhere
Anywhere
Anywhere
Anywhere
Anywhere
Anywhere
Only within $hoppingWindow or $tumblingWindow stages.
Only within $hoppingWindow or $tumblingWindow stages.
Only within $hoppingWindow or $tumblingWindow stages.
Only within $hoppingWindow or $tumblingWindow stages.

Atlas Stream Processing provides a number of extensions to the core MongoDB Aggregation Pipeline syntax. To learn more about these extensions, see Supported Aggregation Pipeline Stages.

Certain core Aggregation Pipeline stages have limited support, or are unsupported as noted in the following table. If a stage is not listed in the table, Atlas Stream Processing supports it.

Aggregation Stage
Support Status
Only supported in a $tumblingWindow or $hoppingWindow.
Only supported in a $tumblingWindow or $hoppingWindow.
Only supported in a $tumblingWindow or $hoppingWindow.
Only supported in a $tumblingWindow or $hoppingWindow.
Supported with modified syntax. For more information, see $merge.
Supported with modified syntax. For more information, see $lookup.

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