Abstract: The present invention relates to compression of values and bitmaps, and methods thereof. Such methods are configured for operating on a computer system having a word length architecture of length WL and are based on the observation that not all the bits used for the run-length counter—i.e., the fill length field (FL) inhere—are often used, since runs are seldom so long. Contrarily to other compression schemes (e.g., WAH), said methods may assign the unused bits to one or more position list fields (PL, PL1, PL2, PLs), thus boosting the compression ratio. Moreover, the total length (in terms of number of bits) of the uncompressed data—comprising values or bitmaps—may be stored just once, preferably at the beginning of the compression, thus dramatically diminishing the storage requirements for the compression scheme, since it is not required to keep track of the length of each bitmap word while performing the compression or the decompression.

Abstract: The present invention relates to compression of values and bitmaps, and methods thereof. Such methods are configured for operating on a computer system having a word length architecture of length WL and are based on the observation that not all the bits used for the run-length counter—i.e., the fill length field (FL) inhere—are often used, since runs are seldom so long. Contrarily to other compression schemes (e.g., WAH), said methods may assign the unused bits to one or more position list fields (PL, PL1, PL2, PLs), thus boosting the compression ratio. Moreover, the total length (in terms of number of bits) of the uncompressed data—comprising values or bitmaps—may be stored just once, preferably at the beginning of the compression, thus dramatically diminishing the storage requirements for the compression scheme, since it is not required to keep track of the length of each bitmap word while performing the compression or the decompression.

Abstract: A method, a computer system and a computer program product for a computer system for transforming general On-line Analytical Processing (OLAP) hierarchies into summarizable hierarchies whereby pre-aggregation is disclosed, by which fast query response times for aggregation queries without excessive storage use is made possible even when the hierarchies originally are irregular. Pre-aggregation is essential for ensuring adequate response time during data analysis. Most OLAP systems adopt the practical pre-aggregation approach, as opposed to full pre-aggregation, of materializing only select combinations of aggregates and then re-use these for efficiently computing other aggregates. However, this re-use of aggregates is contingent on the dimension hierarchies and the relationships between facts and dimensions satisfying stringent constraints.