Wah
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WAH (word-aligned hybrid), efficient bitmap index compressAlgorithm 2020. 12. 6. 17:21
WAH(word-aligned hybrid) is very efficent way to compress bitmap index. Of course we have another compression methods, but WAH compressed bitmap can be used to logcial operation without decompression, while other methods requrie decompression before we do any logical operatoin. Summary of WAH WAH compression is done in 32bit, both 31 and 30 bits are special meaning like below. 31 bit : Indicates..
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Bitmap index의 WAH 압축방식이 설명되어 있는 논문Development 2020. 10. 4. 14:24
Bitmap index의 WAH 압축방식이 설명되어 있는 논문링크입니다. Optimizing bitmap indices with efficient compression www.researchgate.net/publication/200084986_Optimizing_bitmap_indices_with_efficient_compression (PDF) Optimizing bitmap indices with efficient compression PDF | Bitmap indices are efficient for answering queries on low-cardinality attributes. In this article, we present a new compression scheme called....
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Bitmap index에서 WAH 사용시 장점Algorithm 2020. 9. 6. 21:28
(위키피디아에서 일부분 밝췌함) These compression methods require very little effort to compress and decompress. 이런 압축방법들(Bitmap index의 여러가지 압축방법들을 말함), 압축과 압축풀기를 매우 쉽게 할 수 있다. More importantly, bitmaps compressed with BBC, WAH, COMPAX, PLWAH, EWAH and CONCISE can directly participate in bitwise operations without decompression. 보다 중요한 점은, BBC, WAH, COMPAX, PLWAH, EWAH and CONCISE와 같은 비트맵 압축방법은 압축풀지 않고, 바로 비트..