Query Processing and Optimization
Query Processing and Optimization
Query Processing and Optimization
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Example of Sort-Merge Join<br />
• Cost to sort CheckedOut (b CheckedOut = 10)<br />
• Cost Sort ChecedOut = 2 × 2.000 + 2 × 2.000 × ⎡log 5 (2.000/6)⎤ = 20.000<br />
• Cost to sort Customer relation (b Customer = 10)<br />
• Cost Sort Customer = 2 × 10 + 2 × 10 × ⎡log 5 (10/6)⎤ = 40<br />
• Cost for merge join<br />
• Cost to scan sorted Customer + cost to scan sorted CheckedOut<br />
• Cost merge join = 10 + 2.000 = 2.010<br />
• Cost sort-merge join = Cost Sort Customer + Cost Sort ChecedOut + Cost merge join<br />
• Cost sort-merge join = 20.000 + 40 + 2.010 = 22.050<br />
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