# Use Asynchronous I/O in Managed Service for Apache Flink
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An Asynchronous I/O operator enriches stream data using an external data source such as a database. Managed Service for Apache Flink enriches the stream events asynchronously so that requests can be batched for greater efficiency. 

For more information, see [Asynchronous I/O](https://nightlies.apache.org/flink/flink-docs-release-1.19/docs/dev/datastream/operators/asyncio/) in the Apache Flink Documentation.