As we are working on complex trading systems it is frequently necessary to correct past record and then be able to make consistent reports based on "as of" date

As we are working on complex trading systems it is frequently necessary to correct past record and then be able to make consistent reports based on "as of" date. This means answering questions like "I want to get the state of this population of trades as it was yesterday at 5 pm but based on our knowledge yesterday at 10 pm." Pretty fun actually when you have billions of these records:)