I am completely new to this and i have a basic question. I was just taking some classes on DS and i came up with a question. How do i know what kind of errors are there in the heterogeneous data sources that iam going to stage. Say if it has 1 million records. I know that i cant go through each and every record and i also think that i cant write a sql code because i dont know what kind of errors it has. Please do let me know how the flow or process actually works?