Open access research
publication repository

Attribute value reordering for efficient hybrid OLAP [r-libre/205]

Kaser, Owen, & Lemire, Daniel (2006). Attribute value reordering for efficient hybrid OLAP. Information Systems, 176 (16), 2304-2336. https://doi.org/10.1016/j.ins.2005.09.005

File(s) available for this item:
[img]  PDF - is2004_web.pdf  
Item Type: Journal Articles
Refereed: Yes
Status: Published
Abstract: The normalization of a data cube is the ordering of the attribute values. For large multidimensional arrays where dense and sparse chunks are stored differently, proper normalization can lead to improved storage efficiency. We show that it is NP-hard to compute an optimal normalization even for 1x3 chunks, although we find an exact algorithm for 1x2 chunks. When dimensions are nearly statistically independent, we show that dimension-wise attribute frequency sorting is an optimal normalization and takes time O(d n log(n)) for data cubes of size n^d. When dimensions are not independent, we propose and evaluate several heuristics. The hybrid OLAP (HOLAP) storage mechanism is already 19%-30% more efficient than ROLAP, but normalization can improve it further by 9%-13% for a total gain of 29%-44% over ROLAP.
Depositor: Lemire, Daniel
Owner / Manager: Daniel Lemire
Deposited: 05 Jun 2007
Last Modified: 16 Jul 2015 00:47

Actions (login required)