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azureazure-eventhubazure-stream-analytics

Azure Stream Analytics Event Hub No Events

An Azure Stream Analytics job exports events to an Azure Event Hub, based on this Query:

SELECT ipAddress, httpRequestTime
INTO Outlet
FROM Inlet
TIMESTAMP BY HttpRequestTime

No events are output to the Event Hub. However, if I change the Query, removing the TIMESTAMP clause, all events are output:

SELECT ipAddress, httpRequestTime
INTO Outlet
FROM Inlet

Why does the TIMESTAMP clause perclude the events from reaching the Event Hub?

Incidentally, if the point of this Query is unclear, the original Query was more complex, and by process-of-elimination, I have isolated to problem to the TIMESTAMP clause.

Solution

  • The Partition Key changed multiple times during development, which seems to have disrupted the mapping between Stream Analytics job and downstream Event Hub Partitions, resulting in message-loss.

    Deleting and re-creating both up and downstream Event Hubs, and resetting the associated Stream Analytics input and outputs, re-calibrated the Partition-mappings and resolved the issue.

    This answer outlines the underlying cause in detail.