The Experts below are selected from a list of 5154 Experts worldwide ranked by ideXlab platform
Yibin Chen - One of the best experts on this subject based on the ideXlab platform.
-
Signature File hierarchies and Signature graphs a new index method for object oriented databases
ACM Symposium on Applied Computing, 2004Co-Authors: Yangjun Chen, Yibin ChenAbstract:In this paper, we propose a new index structure for object-oriented databases. The main idea of this is a graph structure, called a Signature graph, which is constructed over a Signature File generated for a class and improves the search of a Signature File dramatically. In addition, the Signature Files (accordingly, the Signature graphs) can be organized into a hierarchy according to the nested structure (called the aggregation hierarchy) of classes in an object-oriented database, which leads to another significant improvements.
Yangjun Chen - One of the best experts on this subject based on the ideXlab platform.
-
Signature File hierarchies and Signature graphs a new index method for object oriented databases
ACM Symposium on Applied Computing, 2004Co-Authors: Yangjun Chen, Yibin ChenAbstract:In this paper, we propose a new index structure for object-oriented databases. The main idea of this is a graph structure, called a Signature graph, which is constructed over a Signature File generated for a class and improves the search of a Signature File dramatically. In addition, the Signature Files (accordingly, the Signature graphs) can be organized into a hierarchy according to the nested structure (called the aggregation hierarchy) of classes in an object-oriented database, which leads to another significant improvements.
Gaurav Patel - One of the best experts on this subject based on the ideXlab platform.
-
efficient Signature File methods for text retrieval
Data and Knowledge Engineering, 1995Co-Authors: Dik Lun Lee, Young Man Kim, Gaurav PatelAbstract:Signature Files have been studied extensively, as an access method for textual databases. Many approaches have been proposed for searching Signatures Files efficiently. However, different methods make different assumptions and use different performance measures, making it difficult to compare their performance. In this paper, we study three basic methods proposed in the literature, namely, the indexed descriptor File, the two-level superimposed coding scheme, and the partitioned Signature File approach. The contribution of this paper is two-fold. First, we present a uniform analytical performance model so that the methods can be compared fairly and consistently. The analysis shows that the two-level superimposed coding scheme, if stored in a transposed File, has the best performance. Second, we extend the two-level superimposed coding method into a multilevel superimposed coding method, we obtain the optimal number of levels for the multilevel method and show that for databases with reasonable size the optimal value is much larger than 2, which is assumed in the two-level method. The accuracy of the analytical formula is demonstrated by simulation. >
Jaewoo Chang - One of the best experts on this subject based on the ideXlab platform.
-
vertically partitioned parallel Signature File method
Journal of Systems Architecture, 2000Co-Authors: Jeongki Kim, Jaewoo ChangAbstract:Abstract Recently, parallel Signature File methods have been proposed for better retrieval performance in Signature Files. In this paper, we propose a vertically-partitioned parallel Signature File (VPSF) method which can partition a Signature File vertically. Our VPSF method uses an extendable hashing technique for dynamic environment and uses a frame-sliced Signature File technique for efficient retrieval. Our VPSF method also can eliminate the data skew and the execution skew by allocating each frame to a processing node. To prove the efficiency of our VPSF method, we compare its performance with those of the conventional parallel Signature File methods, i.e., HPSF and Hamming filter, in terms of retrieval time, storage overhead, and insertion time. The experimental result shows that our VPSF achieves about 40% better retrieval performance than the Hamming filter. In addition, we evaluate the performance of our VPSF methods on several normal distributions with half and double standard deviations of the real data. From the performance evaluation on record sets with half standard deviation, we show that our VPSF gains about 20–50% improvement in retrieval time, compared with the Hamming filter and the HPSF. Finally, we show that our VPSF generally outperforms the conventional parallel Signature Files on retrieval performance when the records of a database are uniform in size.
-
two dimensional dynamic Signature File method using extendible hashing and frame slicing techniques
Information Sciences, 1997Co-Authors: Jeongki Kim, Choonhee Lee, Jaewoo ChangAbstract:The Signature File method has been widely advocated as an efficient index scheme to handle applications demanding a large amount of text databases. Moreover, many recent applications in practice require a dynamic information storage structure. For this, in this paper, we propose two-dimensional dynamic Signature File (TDSF) methods using multilevel extendible hashing and frame-slicing techniques in order to efficiently handle text and multiattribute data in dynamic environments. Due to the characteristics of the extendible hashing technique, the TDSF is suitable for supporting insertions, deletions, and updates. Based on the frame-slicing technique, we divide a Signature into several frames, and store each frame in a separate File so that we may increase the filtering effect of the Signature File, leading to a decrease in the amount of retrieval required for searching a query. We also describe the storage structure of the TDSF and outline algorithms for Signature insertion, retrieval, and deletion. Finally, we derive analytic performance evaluation models of the TDSF methods, and perform extensive experiments with various frame divisions. We show from performance results that, regardless of the database size, the TDSF methods outperform the Quick Filter method in terms of both retrieval time and dynamic operating measure considering the degree of dynamic environment.
Chiyin Wong - One of the best experts on this subject based on the ideXlab platform.
-
chinese document indexing based on a new partitioned Signature File model and evaluation
Journal of the Association for Information Science and Technology, 2001Co-Authors: Wai Lam, Kamfai Wong, Chiyin WongAbstract:In this article we investigate the use of Signature Files in Chinese information retrieval system and propose a new partitioning method for Chinese Signature File based on the characteristic of Chinese words. Our partitioning method, called Partitioned Signature File for Chinese (PSFC), offers faster search efficiency than the traditional single Signature File approach. We devise a general scheme for controlling the trade-off between the false drop and storage overhead while maintaining the search space reduction in PSFC. An analytical study is presented to support the claims of our method. We also propose two new hashing methods for Chinese Signature Files so that the Signature File will be more suitable for dynamic environment while the retrieval performance is maintained. Furthermore, we have implemented PSFC and the new hashing methods, and we evaluated them using a large-scale real-world Chinese document corpus, namely, the TREC-5 (Text REtrieval Conference) Chinese collection. The experimental results confirm the features of PSFC and demonstrate its superiority over the traditional single Signature File method.