1,721,053 research outputs found
DIPS: an efficient pointer swizzling strategy for incremental uncaching environments
No full textPointer swizzling improves the performance of OODBMSs by reducing the number of table lookups. However, the object replacement incurs the unswizzling overhead. In this paper, we propose a new pointer swizzling strategy, the dynamic indirect pointer swizzling (DIPS). DIPS dynamically applies pointer swizzling techniques in order to reduce the overhead of unswizzling. DIPS uses the temporal locality information which is gathered by the object buffer manager. The information is used to select the object to whose pointers the pointer swizzling techniques are applied and to dynamically bind the pointer swizzling techniques using the virtual function mechanism. We show the efficiency of the proposed strategy through experiments over various object buffer sizes and workloads. (C) 2003 Elsevier Inc. All rights reserved
A cost model for spatio-temporal queries using the TPR-tree
No full textA query optimizer requires cost models to calculate the costs of various access plans for a query. An effective method to estimate the number of disk (or page) accesses for spatio-temporal queries has not yet been proposed. The TPR-tree is an efficient index that supports spatio-temporal queries for moving objects. Existing cost models for the spatial index such as the R-tree do not accurately estimate the number of disk accesses for spatio-temporal queries using the TPR-tree, because they do not consider the future locations of moving objects, which change continuously as time passes. In this paper, we propose an efficient cost model for spatio-temporal queries to solve this problem. We present analytical formulas which accurately calculate the number of disk accesses for spatio-temporal queries. Extensive experimental results show that our proposed method accurately estimates the number of disk accesses over various queries to spatio-temporal data combining real-life spatial data and synthetic temporal data. To evaluate the effectiveness of our method, we compared our spatio-temporal cost model (STCM) with an existing spatial cost model (SCM). The application of the existing SCM has the average error ratio from 52% to 93%, whereas our STCM has the average error ratio from 11% to 32%. (C) 2003 Elsevier Inc. All rights reserved
An adaptive indexing technique using spatio-temporal query workloads
No full textMany spatio-temporal access methods, such as the HR-tree, the 3DR-tree, and the MV3R-tree, have been proposed for timestamp and interval queries. However, these access methods have the following problems: the poor performance of the 3DR-tree for timestamp queries, the huge size and the poor performance of the HR-tree for interval queries, and the large size and the high update cost of the MV3R-tree. We address these problems by proposing an adaptive partitioning technique called the Adaptive Partitioned R-tree (APR-tree) using workloads with timestamp and interval queries. The APR-tree adaptively partitions the time domain using query workloads. Since the time domain of the APR-tree is automatically fitted to query workloads, the APR-tree outperforms the other access methods for various query workloads. The size of the APR-tree is on the average 1.3 times larger than that of the 3DR-tree which has the smallest size. The update cost of the APR-tree is on the average similar to that of the 3DR-tree which has the smallest update cost. (C) 2003 Elsevier B.V. All rights reserved
Efficient extraction of schemas for XML documents
No full textIn this paper, we present a technique for efficient extraction of concise and accurate schemas for XML documents. By restricting the schema form and applying some heuristic rules, we achieve the efficiency and conciseness. The result of an experiment with real-life DTDs shows that our approach attains high accuracy and is 20 to 200 times faster than existing approaches. (C) 2002 Elsevier Science B.V All rights reserved.This work was supported by the Brain Korea 21 Project
Structural Function Inlining Technique for Structurally Recursive XML Queries
Full text linkKowloon Shangri-La Hotel
August 20-23, 2002
Hong Kong, Chin
XPRESS: A Queriable Compression for XML Data
Full text linkACM SIGMOD International Conference on Management of Data(San Diego, California
June 9-12, 2003)Information Technology Research Cente
APEX: An adaptive path index for XML data
Full text linkVLDB 2002, Proceedings of 28th International Conference on Very Large Data Bases, August 20-23, 2002, Hong Kong, China.This work was supported by the Brain Korea 21 Project.
The support of Yesook Shim is greatly appreciated
Multi-way R-tree joins using indirect predicates
No full textSince spatial join processing consumes much time, several algorithms have been proposed to improve spatial join performance. Spatial join has been processed in two steps, called filter step and refinement step. The M-way R-tree join (MRJ) is a filter step join algorithm, which synchronously traverses M R-trees. In this paper, we introduce indirect predicates which do not directly come from the multi-way join conditions but are indirectly derived from them. By applying indirect predicates as well as direct predicates to MRJ, we can quickly remove the minimum bounding rectangle (MBR) combinations which do not satisfy the direct predicates or the indirect predicates at the parent level. Hence we can reduce the intermediate MBR combinations for the input to the child level processing and improve the performance of MRJ. We call such a multi-way R-tree join algorithm using indirect predicates indirect predicate filtering (IPF). Through experiments using synthetic data and real data, we show that IPF significantly improves the performance of MRJ. (C) 2004 Elsevier B.V. All rights reserved.This work was supported by the Ministry of Information
and Communication of Korea through the research grant
of IITA
A compression method for prefix-sum cubes
No full textThis research was supported by University IT
Research Center Project
- …
