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9 Cards in this Set
- Front
- Back
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A.C.I.D.
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Atomicity
Consistency preservation Isolation Durability or permanency |
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Atomicity
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A transaction is an atomic unit of processing; it is either preformed in its entirety or not preformed at all
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Consistency preservation
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A transaction is consistency preserving if its complete execution take(s) the database from one consistent state to another.
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Isolation
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A transaction should appear as though it is being executed in isolation from other transactions. That is, the execution of a transaction should not be interfered with by any other transactions executing concurrently
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Durability or permanency
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The changes applied to the database by a committed transaction must persist in the database. These changes must not be lost because of any failure.
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Database State
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a collection of all the stored data items (values) in the database at a given point in time
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Consistent State
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Satisfies the constraints specified in the schema as well as any other constraints that should hold on the database.
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Schedule or History
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The order of execution of operations from various transactions are executing concurrently in an interleaved fashion.
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Two operations in a schedule are said to conflict if they satisfy all three of these conditions
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(1) They belong to different transactions
(2) They access the same item X (3) At least one of the operations is a write(X) |
