This is not about an external table. Instead, in an Azure Synapse Analytics pipeline, you use a Get Metadata activity that retrieves the DateTime of the files. Note: You can use the Get Metadata activity to retrieve the metadata of any data in Azure Data Factory or a Synapse pipeline. You can use the output from the Get Metadata activity in conditional expressions to perform validation, or consume the metadata in subsequent activities. Reference: https://docs.microsoft.com/en-us/azure/data-factory/control-flow-get-metadata-activity