Principles of Database Management Systems - Notes 6: Crash Recovery presents about Integrity or correctness of data, Integrity or consistency constraints, prevent/fix violations, Failure Model, Context of failure model. | Principles of Database Management Systems Notes 6: Crash Recovery Based on lecture notes by Hector Garcia-Molina 1 PART II of Course Major concern so far: How to manipulate database efficiently? Now shift focus to: How to ensure correctness of database manipulation? 2 Integrity or correctness of data Would like data to be “accurate” or “correct” at all times EMP Name Age White 52 Green 3421 Gray 1 3 Integrity or consistency constraints Predicates that the data must satisfy Examples: - x is key of relation R - x y holds in R - Domain(x) = {Red, Blue, Green} - no employee should make more than twice the average salary 4 Definition: Consistent state: satisfies all constraints Consistent DB: DB in a consistent .
