Using google cloud dataflow PubSubIO, when does the read of the message get acknowledged?

Question

Is it possible to delay acknowledgement until the subgraph (everything below the PubSubIO.Read) is successfully processed?

For example, we are streaming

Answer 1

The acknowledgement will be made once the message is durable persisted somewhere in the Dataflow pipeline. If you want to make changes to a pipeline without losing in-flight data, use the Update feature instead of Cancel: https://cloud.google.com/dataflow/pipelines/updating-a-pipeline