Customer is not giving us production data to analyse citing security concerns.He is giving us only sample data and record count for source and Target tables.But in some cases the record count is of order of 600 million.So without having any production data it is becoming very difficult to tune the queries and make sure they are performing fine.In my previous project Customer used to give production data.
Do most customers dont give data to work with or it is the same everywhere?
It varies from project to project. Most of the customers do not share the data due to security reasons (as in your case). Some of them provide encrypted data.
So in many cases, development and testing is done on sample data.