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Bitmap indexes are commonly used in databases and search engines. By exploiting bit-level parallelism, they can significantly accelerate queries. However, they can use much memory, and thus we might prefer compressed bitmap indexes.…

Databases · Computer Science 2016-04-12 Samy Chambi , Daniel Lemire , Owen Kaser , Robert Godin

Compressed bitmap indexes are used in systems such as Git or Oracle to accelerate queries. They represent sets and often support operations such as unions, intersections, differences, and symmetric differences. Several important systems…

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)…

Databases · Computer Science 2016-08-02 Daniel Lemire , Owen Kaser , Kamel Aouiche

Bitmap indexes are frequently used to index multidimensional data. They rely mostly on sequential input/output. Bitmaps can be compressed to reduce input/output costs and minimize CPU usage. The most efficient compression techniques are…

Databases · Computer Science 2008-08-15 Kamel Aouiche , Daniel Lemire , Owen Kaser

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)…

Databases · Computer Science 2009-01-19 Owen Kaser , Daniel Lemire , Kamel Aouiche

The Run Length Encoding (RLE) compression method is a long standing simple lossless compression scheme which is easy to implement and achieves a good compression on input data which contains repeating consecutive symbols. In its pure form…

Data Structures and Algorithms · Computer Science 2021-04-01 Sven Fiergolla , Petra Wolf

Run Length Encoding(RLE) is one of the oldest algorithms for data-compression available, a method used for compression of large data into smaller and therefore more compact data. It compresses by looking at the data for repetitions of the…

Data Structures and Algorithms · Computer Science 2015-01-23 Meo Mespotine

Bit arrays, or bitmaps, are used to significantly speed up set operations in several areas, such as data warehousing, information retrieval, and data mining, to cite a few. However, bitmaps usually use a large storage space, thus requiring…

Data Structures and Algorithms · Computer Science 2015-03-14 Alessandro Colantonio , Roberto Di Pietro

In this paper, we will present p roposed enhance process of image compression by using RLE algorithm. This proposed yield to decrease the size of compressing image, but the original method used primarily for compressing a binary images…

Multimedia · Computer Science 2018-04-03 Ali H. Husseen Al-nuaimi , Shyamaa Shakir Al-juboori , R. J. Mohammed

Run-Length Encoding (RLE) is one of the most fundamental tools in data compression. However, its compression power drops significantly if there lacks consecutive elements in the sequence. In extreme cases, the output of the encoder may…

Data Structures and Algorithms · Computer Science 2023-12-29 Xutan Peng , Yi Zhang , Dejia Peng , Jiafa Zhu

Two decades ago, a breakthrough in indexing string collections made it possible to represent them within their compressed space while at the same time offering indexed search functionalities. As this new technology permeated through…

Data Structures and Algorithms · Computer Science 2022-11-28 Gonzalo Navarro

Finding desired information from large data set is a difficult problem. Information retrieval is concerned with the structure, analysis, organization, storage, searching, and retrieval of information. Index is the main constituent of an IR…

Information Retrieval · Computer Science 2012-09-26 Md. Abdullah al Mamun , Md. Hanif , Md. Rakib Uddin , Tanvir Ahmed , Md. Mofizul Islam

With lowrank approximation the storage requirements for dense data are reduced down to linear complexity and with the addition of hierarchy this also works for data without global lowrank properties. However, the lowrank factors itself are…

Mathematical Software · Computer Science 2023-08-23 Ronald Kriemann

Rank and select queries on bitmaps are essential building bricks of many compressed data structures, including text indexes, membership and range supporting spatial data structures, compressed graphs, and more. Theoretically considered yet…

Data Structures and Algorithms · Computer Science 2016-05-13 Szymon Grabowski , Marcin Raniszewski

Compression is beneficial because it helps detract resource usage. It reduces data storage space as well as transmission traffic and improves web pages loading. Run-length coding (RLC) is a lossless data compression algorithm. Data are…

Data Structures and Algorithms · Computer Science 2016-11-30 Kaveh Geyratmand Haghighi , Mirkamal Mirnia , Ahmad Habibizad Navin

Compression of inverted lists with methods that support fast intersection operations is an active research topic. Most compression schemes rely on encoding differences between consecutive positions with techniques that favor small numbers.…

Information Retrieval · Computer Science 2009-11-18 Francisco Claude , Antonio Farina , Gonzalo Navarro

We present shuffle coding, a general method for optimal compression of sequences of unordered objects using bits-back coding. Data structures that can be compressed using shuffle coding include multisets, graphs, hypergraphs, and others. We…

Machine Learning · Computer Science 2024-08-19 Julius Kunze , Daniel Severo , Giulio Zani , Jan-Willem van de Meent , James Townsend

Reranking, the process of refining the output from a first-stage retriever, is often considered computationally expensive, especially when using Large Language Models (LLMs). A common approach to mitigate this cost involves utilizing…

Information Retrieval · Computer Science 2026-04-30 Hervé Déjean , Stéphane Clinchant

In-memory columnar databases have become mainstream over the last decade and have vastly improved the fast processing of large volumes of data through multi-core parallelism and in-memory compression thereby eliminating the usual…

Databases · Computer Science 2016-09-27 Jayanth Jayanth

The data structure at the core of large-scale search engines is the inverted index, which is essentially a collection of sorted integer sequences called inverted lists. Because of the many documents indexed by such engines and stringent…

Information Retrieval · Computer Science 2022-02-08 Giulio Ermanno Pibiri , Rossano Venturini
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