When you need to make changes to a stack's settings or change its resources, you update the stack instead of deleting it and creating a new stack.For example, if you have a stack with an EC2 instance, you can update the stack to change the instance's AMI ID.creates and names a temporary variable that contains an end-of-file indicator. Usually, the master data set and the transaction data set contain the same variables.
The resulting value in the master data set will be a period (.) for missing numeric values and a blank for missing character values.
For example, you can use a change set to verify that AWS Cloud Formation won't replace your stack's database instances during an update.
Dropping, keeping, and renaming variables is often useful when you update a data set.
Renaming like-named variables prevents the second value that is read from over-writing the first one.
By renaming one variable, you make the values of both of them available for processing, such as comparing.