I want to work on the code of intermediate dataset of select and update query.
For example.
Rohit's salary has been updated 4 times, so it has 4 different version of salary.
I want to select salary of person named Rohit. Now suppose , in intermediate result, I found 4 different versions of the data. I want to know the code portion which i need to look for working on all 4 versions in dataset. :)
Thanks in advance!!
Not sure what you are looking for, but each update is an insert of a new tuple with the new values and marking the old tuple as deleted.
There is no need for tracking the versions of any changes in data set. Each update operation leaves only one visible tuple. If the transaction commits, inserted tuple becomes visible and old row is marked deleted. If the transaction rollbacks, only the old tuple shall remain visible.
