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Wyszukujesz frazę "Wrembel, W." wg kryterium: Autor


Wyświetlanie 1-2 z 2
Tytuł:
Predicting access to materialized methods by means of hidden Markov model
Autorzy:
Masewicz, M.
Andrzejewski, W.
Wrembel, W.
Królikowski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/970822.pdf
Data publikacji:
2009
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
method materialization
hierarchical materialization
access prediction
hidden Markov model
Opis:
Method materialization is a promising data access optimization technique for multiple applications, including, in particular object programming languages with persistence, object databases, distributed computing systems, object-relational data warehouses, multimedia data warehouses, and spatial data warehouses. A drawback of this technique is that the value of a materialized method becomes invalid when an object used for computing the value of the method is updated. As a consequence, a materialized value of the method has to be recomputed. The materialized value can be recomputed either immediately after updating the object or just before calling the method. The moment the method is recomputed bears a strong impact on the overall system performance. In this paper we propose a technique of predicting access to materialized methods and objects, for the purpose of selecting the most appropriate recomputation technique. The prediction technique is based on the Hidden Markov Model (HMM). The prediction technique was implemented and evaluated experimentally. Its performance characteristics were compared to: immediate recomputation, deferred recomputation, random recomputation, and to our previous prediction technique, called a PMAP.
Źródło:
Control and Cybernetics; 2009, 38, 1; 127-152
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
GPU-PLWAH: GPU-based implementation of the PLWAH algorithm for compressing bitmaps
Autorzy:
Andrzejewski, W.
Wrembel, R.
Powiązania:
https://bibliotekanauki.pl/articles/206057.pdf
Data publikacji:
2011
Wydawca:
Polska Akademia Nauk. Instytut Badań Systemowych PAN
Tematy:
data warehouse
GPGPU
bitmap index
bitmap index compression
PLWAH
WAH
Opis:
Bitmap indexes are data structures applied to index- ing attributes in databases and data warehouses. A drawback of a bitmap index is that its size increases when the domain of an indexed attribute increases. As a consequence, for wide domains, the size of a bitmap index is too large to be efficiently processed. Hence, various techniques of compressing bitmap indexes have been proposed. A compression technique incurs some system overhead (mainly CPU) for compression and decompression operations. For this reason, we propose to use additional processing power of graphical processing units (GPUs). In this paper, we present the GPU-PLWAH algorithm that is a parallel implementation of the recently developed PLWAH compression algorithm. GPU-PLWAH was experimentally compared to its traditional CPU version as well as to our previously developed parallel GPU implementation of the WAH compression algorithm. The experiments show that applying GPUs significantly reduces compression/decompression time.
Źródło:
Control and Cybernetics; 2011, 40, 3; 627-650
0324-8569
Pojawia się w:
Control and Cybernetics
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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