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Reordering rows for better compression: Beyond the lexicographic order [r-libre/196]

Lemire, Daniel; Kaser, Owen et Gutarra, Eduardo (2012). Reordering rows for better compression: Beyond the lexicographic order. ACM Transactions on Database Systems, 37 (3). https://doi.org/10.1145/2338626.2338627

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[img]  PDF - 1207.2189v3.pdf  
Catégorie de document : Articles de revues
Évaluation par un comité de lecture : Oui
Étape de publication : Publié
Résumé : Sorting database tables before compressing them improves the compression rate. Can we do better than the lexicographical order? For minimizing the number of runs in a run-length encoding compression scheme, the best approaches to row-ordering are derived from traveling salesman heuristics, although there is a significant trade-off between running time and compression. A new heuristic, Multiple Lists, which is a variant on Nearest Neighbor that trades off compression for a major running-time speedup, is a good option for very large tables. However, for some compression schemes, it is more important to generate long runs rather than few runs. For this case, another novel heuristic, Vortex, is promising. We find that we can improve run-length encoding up to a factor of 3 whereas we can improve prefix coding by up to 80%: these gains are on top of the gains due to lexicographically sorting the table. We prove that the new row reordering is optimal (within 10%) at minimizing the runs of identical values within columns, in a few cases.
Adresse de la version officielle : http://dl.acm.org/citation.cfm?id=2338633&CFID=486...
Déposant: Lemire, Daniel
Responsable : Daniel Lemire
Dépôt : 14 juill. 2014 20:13
Dernière modification : 16 juill. 2015 00:46

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