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12 Cards in this Set
- Front
- Back
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Every relation has
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a name,
a set of attributes, and each attribute associated with a domain. |
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Relation
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An instance of a relation is a finite set of tuples.
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Keys for a Relation
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A minimal set of attributes whose values uniquely
identify a tuple in any instance of the relation. No proper subsets of the attributes retain the property. |
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Types of Indexes
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B-tree: Fits most common situations
Hash: Only handles equality comparisons GiST: Generalized Search Tree is a balanced tree structure GIN: Generalized Inverted Index is designed for composite value keys |
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Transaction
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a single logical database operation.
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ACID Properties of Relational Databases
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Atomicity, Consistency, Isolation, Durability
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Atomicity
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Insert/update/delete is performed completely or not at all
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Consistency
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No part of a transaction can violate constraints
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Isolation
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Each application runs transactions independently
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Durability
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Completed transactions persist
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SQL Savepoints
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used to record intermediate points within a transaction, but before a commit.
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RELEASE
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has the effect of deleting the save point, but keeping results of the statements that followed.
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