How can we get messages from a particular event hub partition into azure function and how to automatically scale up number of azure function?

Question

I can get the messages from all the partitions of event hub in azure function but I want to get messages from a particular event hub partition in azure function. Is there a way to do that ? And one other thing I want to do is to increase (scale out) the number of azure functions to process messages if there are large number of backlogs messages to process. How can I do that ? Is there any formulae to solve my second problem ?

Answer 1

In the Azure Functions Consumption plan, scale out is handled automatically for you. If we see that your function is not keeping up with the event stream, we'll add new instances. Those instances will cooperate to process the event stream in parallel.

For reading of the event stream, we rely on the Event Hubs EventProcessorHost as described in their documentation here. This host manages coordination of partition leases with other instances when the Function App starts - this isn't something you can (or should want to) control.