Immutability and Immortality
One of the most important features of serious Big Data resources is immutability. The rule is simple. Data is immortal and cannot change. You can add data to the system, but you can never alter data and you can never erase data. Immutability is a counterintuitive concept for many people, including some data analysts. If a patient has a glucose level of 100 on Monday, and the same patient has a glucose level of 115 on Tuesday, then it would seem obvious that his glucose level changed between Monday and Tuesday. Not so. Until the end of time, Monday's glucose level will always be 100. On Tuesday, another glucose level was added to the record for the patient. Nothing that existed prior to Tuesday was changed. ...
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