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Lemire, Daniel, & Kaser, Owen (2011). Reordering Columns for Smaller Indexes. Information Sciences, 181 (12), 2550–2570. https://doi.org/10.1016/j.ins.2011.02.002
File(s) available for this item:| PDF - 0909.1346v8.pdf |
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| Item Type: | Journal Articles |
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| Refereed: | Yes |
| Status: | Published |
| Abstract: | Column-oriented indexes-such as projection or bitmap indexes-are compressed by run-length encoding to reduce storage and increase speed. Sorting the tables improves compression. On realistic data sets, permuting the columns in the right order before sorting can reduce the number of runs by a factor of two or more. Unfortunately, determining the best column order is NP-hard. For many cases, we prove that the number of runs in table columns is minimized if we sort columns by increasing cardinality. Experimentally, sorting based on Hilbert space-filling curves is poor at minimizing the number of runs. |
| Official URL: | http://www.sciencedirect.com/science/article/pii/S... |
| Depositor: | Lemire, Daniel |
| Owner / Manager: | Daniel Lemire |
| Deposited: | 12 Sep 2014 19:25 |
| Last Modified: | 16 Jul 2015 00:46 |
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