How to configure SQL filter in Azure subscription when we need to pass messages in the same subscription with a custom property and without a custom property?

Question

I am searching for a solution where we need to pass messages to a subscription where we want to add a filter which lets all the messages to be passed accept for a particular condition with a custom property. That is, it excepts all messages which doesn't satisfy the custom property condition and also the ones where no custom property is passed in the message.

Regards,
Hema

Answer 1

A SQL Filter with expression NOT user.<property-name> = '<value>' should do the trick. You can read more about the SQL Filter Syntax in the docs.

But do note that SQL Filters take up processing capacity which could affect throughput across the namespace. Depending on the impact, it might be better to filter them out at the client or use an intermediate service to filter instead like an Azure Function.