我想你在这里已经有了一些建议 

https://***.com/questions/56259168/copy-blob-data -to-sql-database-in-azure-data-factory-with-conditions / 56265030＃56265030

I am trying to perform Copy Activity inside Azure Data Factory where the source are Blobs (JSON) and destination is MySql database.

I do not want certain data to be copied during that activity and that can be determined by reading First key value Element of the Blob's JSON.

Or maybe if it is not possible to stop reading all the BLOB data then at least while writing inside the SQL table I want just some specific data(Like some jsons should be copied and some filtered out on the basis of a key value present inside blob).

The main focus is to reduce the cost of writing irrelevant data, and to decrease the storage after writing.

I think you already have few suggestions here 

https://***.com/questions/56259168/copy-blob-data-to-sql-database-in-azure-data-factory-with-conditions/56265030#56265030