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Applying OLAP Pre-Aggregation Techniques to ... - Jacobs University

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4 Answering Basic Aggregate Queries Using <strong>Pre</strong>-Aggregated Data 63<br />

4.1 Framework . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63<br />

4.1.1 <strong>Aggregation</strong> . . . . . . . . . . . . . . . . . . . . . . . . . . . 64<br />

4.1.2 <strong>Pre</strong>-<strong>Aggregation</strong> . . . . . . . . . . . . . . . . . . . . . . . . 64<br />

4.1.3 Aggregate Query and <strong>Pre</strong>-Aggregate Equivalence . . . . . . . 64<br />

4.2 Cost Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67<br />

4.2.1 Computing Queries from Raw Data . . . . . . . . . . . . . . 68<br />

4.2.2 Computing Queries from Independent and Overlapped <strong>Pre</strong>-<br />

Aggregates . . . . . . . . . . . . . . . . . . . . . . . . . . . 68<br />

4.2.3 Computing Queries from Dominant <strong>Pre</strong>-Aggregates . . . . . 69<br />

4.3 Implementation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70<br />

4.4 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . . . 73<br />

4.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74<br />

5 <strong>Pre</strong>-<strong>Aggregation</strong> Support Beyond Basic Aggregate Operations 77<br />

5.1 Non-Standard Aggregate Operations . . . . . . . . . . . . . . . . . . 77<br />

5.2 Conceptual Framework . . . . . . . . . . . . . . . . . . . . . . . . . 78<br />

5.2.1 Lattice Representation . . . . . . . . . . . . . . . . . . . . . 79<br />

5.2.2 <strong>Pre</strong>-<strong>Aggregation</strong> Selection Problem . . . . . . . . . . . . . . 80<br />

5.3 <strong>Pre</strong>-Aggregates Selection . . . . . . . . . . . . . . . . . . . . . . . . 82<br />

5.3.1 Complexity Analysis . . . . . . . . . . . . . . . . . . . . . . 83<br />

5.4 Answering Scaling Operations Using <strong>Pre</strong>-Aggregated Data . . . . . . 83<br />

5.5 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . . . 85<br />

5.5.1 2D Datasets . . . . . . . . . . . . . . . . . . . . . . . . . . . 86<br />

5.5.2 3D Datasets . . . . . . . . . . . . . . . . . . . . . . . . . . . 91<br />

5.5.3 4D Datasets . . . . . . . . . . . . . . . . . . . . . . . . . . . 98<br />

5.6 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100<br />

6 Conclusion 103<br />

6.1 Future Work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104

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