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Unformatted text preview: 130 Chapter 13 and replaces it with a value from the input buffer. This replacement will only work if the records of the same size. If the entries are of variable size, then we must also keep track of the size of each entry, and replace the moved entry with a new entry that fits in the available memory location. Dynamic programming algorithms have been adapted to decide an optimal replacement strategy in these cases. 14 EVALUATION OF RELATIONAL OPERATORS Exercise 14.1 Briey answer the following questions: 1. Consider the three basic techniques, iteration , indexing , and partitioning , and the relational algebra operators selection , projection , and join . For each technique- operator pair, describe an algorithm based on the technique for evaluating the operator. 2. Define the term most selective access path for a query . 3. Describe conjunctive normal form , and explain why it is important in the context of relational query evaluation. 4. When does a general selection condition match an index? What is a primary term in a selection condition with respect to a given index?...
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This note was uploaded on 01/17/2012 for the course EGN 4302 taught by Professor Dr.vishak during the Fall '12 term at University of Central Florida.
- Fall '12