@Raguram Manokaran Welcome to Microsoft Q&A Forum, Thank you for posting your query here!
I understand that you want to change the default log format of the diagnostic monitor FunctionLogs stored in the Azure Storage.
Please note that, it is not possible to change the default format. However, you can use the Data Flow activity to transform data in Azure Blob Storage using Azure Data Factory or Stream Analytics.
To transform the logs into the expected format using Azure Stream Analytics, you can follow the steps mentioned in the Azure documentation here. For Azure Data Factory, refer this.
More Information about the available logging fields are explained here:
https://video2.skills-academy.com/en-us/azure/azure-monitor/reference/tables/functionapplogs
Hope this helps.
If you have any follow-up questions, please let me know. I would be happy to help.
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