Tweaking slides
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<p class="fragment" data-fragment-index="1" style="font-size: 60%">Some rewrites are situational... we need more information to decide when to apply them.</p>
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<p class="fragment" data-fragment-index="1" style="font-size: 60%">Some rewrites are situational... we need more information to decide when to apply them.</p>
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</section>
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</section>
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<section>
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<h3>General Query Optimizers</h3>
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<ol>
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<li>Push down selections (and optionally projections)</li>
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<li>For each valid join ordering: <span class="fragment">(or for a reasonable subset)</span>
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<ol>
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<li>Figure out the best join <span class="fragment highlight-blue">algorithms</span> and <span class="fragment highlight-blue">access</span> paths</li>
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<li><span class="fragment highlight-blue">Estimate</span> the cost of the resulting <i>execution plan</i></li>
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</ol>
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</li>
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<li>Pick the execution plan with the lowest cost</li>
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</ol>
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</section>
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<section>
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<section>
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<b>Next Class:</b> Extended Relational Algebra and Basic Join Algorithms
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<b>Next Class:</b> Extended Relational Algebra and Basic Join Algorithms
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</section>
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</section>
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