Histogram-Aware Sorting for Enhanced Word-Aligned Compression in Bitmap Indexes
Databases
2009-01-19 v3
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 reordering heuristics based on computed attribute-value histograms. Simply permuting the columns of the table based on these histograms can increase the sorting efficiency by 40%.
Keywords
Cite
@article{arxiv.0808.2083,
title = {Histogram-Aware Sorting for Enhanced Word-Aligned Compression in Bitmap Indexes},
author = {Owen Kaser and Daniel Lemire and Kamel Aouiche},
journal= {arXiv preprint arXiv:0808.2083},
year = {2009}
}
Comments
To appear in proceedings of DOLAP 2008