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Sorting improves word-aligned bitmap indexes [r-libre/228]

Lemire, Daniel; Kaser, Owen, & Aouiche, Kamel (2010). Sorting improves word-aligned bitmap indexes. Data & Knowledge Engineering, 69 (1), 3-28. https://doi.org/10.1016/j.datak.2009.08.006

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Item Type: Journal Articles
Refereed: Yes
Status: Published
Abstract: Bitmap indexes must be compressed to reduce input/output costs and minimize CPU usage. To accelerate logical operations (AND, OR, XOR) over bitmaps, we use techniques based on run-length encoding (RLE), such as Word-Aligned Hybrid (WAH) compression. These techniques are sensitive to the order of the rows: a simple lexicographical sort can divide the index size by 9 and make indexes several times faster. We investigate row-reordering heuristics. Simply permuting the columns of the table can increase the sorting efficiency by 40%. Secondary contributions include efficient algorithms to construct and aggregate bitmaps. The effect of word length is also reviewed by constructing 16-bit, 32-bit and 64-bit indexes. Using 64-bit CPUs, we find that 64-bit indexes are slightly faster than 32-bit indexes despite being nearly twice as large.
Official URL: http://www.sciencedirect.com/science/article/pii/S...
Depositor: Lemire, Daniel
Owner / Manager: Daniel Lemire
Deposited: 28 Jul 2014 18:32
Last Modified: 16 Jul 2015 00:46

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