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1.
Murat Koyuncu 《国际智能系统杂志》2011,26(10):930-951
Multimedia databases have emerged to cope up with the huge amount of multimedia data, which comes up as a result of technological advancement. However, more intelligent techniques are required to satisfy different query requirements of multimedia users. This study extends the query capability of a multimedia database through the integration of a fuzzy rule‐based system. In addition to fuzzy semantic rules, which deduce new information from the data stored in the database, fuzzy spatial and temporal relations, which are inherent to multimedia applications, are defined in the rule‐based system. Users can formulate fuzzy semantic, spatial, temporal, and spatiotemporal queries, resulting in the deduction of new information using the rules defined in the rule‐based system. With some practical examples, the paper presents how a fuzzy rule‐based system integrated to a fuzzy multimedia database improves the query capabilities of the database system intelligently. © 2011 Wiley Periodicals, Inc. 相似文献
2.
Since media-based evaluation yields similarity values, results to a multimedia database query, Q(Y1,…,Yn), is defined as an ordered list SQ of n-tuples of the form X1,…,Xn. The query Q itself is composed of a set of fuzzy and crisp predicates, constants, variables, and conjunction, disjunction, and negation operators. Since many multimedia applications require partial matches, SQ includes results which do not satisfy all predicates. Due to the ranking and partial match requirements, traditional query processing techniques do not apply to multimedia databases. In this paper, we first focus on the problem of “given a multimedia query which consists of multiple fuzzy and crisp predicates, providing the user with a meaningful final ranking”. More specifically, we study the problem of merging similarity values in queries with multiple fuzzy predicates. We describe the essential multimedia retrieval semantics, compare these with the known approaches, and propose a semantics which captures the requirements of multimedia retrieval problem. We then build on these results in answering the related problem of “given a multimedia query which consists of multiple fuzzy and crisp predicates, finding an efficient way to process the query.” We develop an algorithm to efficiently process queries with unordered fuzzy predicates (sub-queries). Although this algorithm can work with different fuzzy semantics, it benefits from the statistical properties of the semantics proposed in this paper. We also present experimental results for evaluating the proposed algorithm in terms of quality of results and search space reduction. 相似文献
3.
Rewriting rules to permeate complex similarity and fuzzy queries within a relational database system
In recent years, the availability of complex data repositories (e.g., multimedia, genomic, semistructured databases) has paved the way to new potentials as to data querying. In this scenario, similarity and fuzzy techniques have proven to be successful principles for effective data retrieval. However, most proposals are domain specific and lack of a general and integrated approach to deal with generalized complex queries, i.e., queries where multiple conditions are expressed, possibly on complex as well as on traditional data. To overcome such limitations, much work has been devoted to the development of middleware systems to support query processing on multiple repositories. On a similar line, We present a formal framework to permeate complex similarity and fuzzy queries within a relational database system. As an example, we focus on multimedia data, which is represented in an integrated view with common database data. We have designed an application layer that relies on an algebraic query language, extended with MM-tailored operators, and that maps complex similarity and fuzzy queries to standard SQL statements that can be processed by a relational database system, exploiting standard facilities of modern extensible RDBMS. To show the applicability of our proposal, we implemented a prototype that provides the user with rich query capabilities, ranging from traditional database queries to complex queries gathering a mixture of Boolean, similarity, and fuzzy predicates on the data. 相似文献
4.
Evaluating refined queries in top-k retrieval systems 总被引:2,自引:0,他引:2
Kaushik Chakrabarti Ortega-Binderberger M. Mehrotra S. Porkaew K. 《Knowledge and Data Engineering, IEEE Transactions on》2004,16(2):256-270
In many applications, users specify target values for certain attributes/features without requiring exact matches to these values in return. Instead, the result is typically a ranked list of "top k" objects that best match the specified feature values. User subjectivity is an important aspect of such queries, i.e., which objects are relevant to the user and which are not depends on the perception of the user. Due to the subjective nature of top-k queries, the answers returned by the system to an user query often do not satisfy the users need right away, either because the weights and the distance functions associated with the features do not accurately capture the users perception or because the specified target values do not fully capture her information need or both. In such cases, the user would like to refine the query and resubmit it in order to get back a better set of answers. While there has been a lot of research on query refinement models, there is no work that we are aware of on supporting refinement of top-k queries efficiently in a database system. Done naively, each "refined" query can be treated as a "starting" query and evaluated from scratch. We explore alternative approaches that significantly improve the cost of evaluating refined queries by exploiting the observation that the refined queries are not modified drastically from one iteration to another. Our experiments over a real-life multimedia data set show that the proposed techniques save more than 80 percent of the execution cost of refined queries over the naive approach and is more than an order of magnitude faster than a simple sequential scan. 相似文献
5.
《Journal of Systems and Software》2004,73(1):113-131
The interest for multimedia database management systems has grown rapidly due to the need for the storage of huge volumes of multimedia data in computer systems. An important building block of a multimedia database system is the query processor, and a query optimizer embedded to the query processor is needed to answer user queries efficiently. Query optimization problem has been widely studied for conventional database systems; however it is a new research area for multimedia database systems. Due to the differences in query processing strategies, query optimization techniques used in multimedia database systems are different from those used in traditional databases. In this paper, a query optimization strategy is proposed for processing spatio-temporal queries in video database systems. The proposed strategy includes reordering algorithms to be applied on query execution tree. The performance results obtained by testing the reordering algorithms on different query sets are also presented. 相似文献
6.
Pradhan S. Tajima K. Tanaka K. 《Knowledge and Data Engineering, IEEE Transactions on》2001,13(5):824-838
While a query result in a traditional database is a subset of the database, in a video database, it is a set of subintervals extracted from the raw video sequence. It is very hard, if not impossible, to predetermine all the queries that will be issued in the future, and all the subintervals that will become necessary to answer them. As a result, conventional query frameworks are not applicable to video databases. We propose a new video query model that computes query results by dynamically synthesizing needed subintervals from fragmentary indexed intervals in the database. We introduce new interval operations required for that computation. We also propose methods to compute relative relevance of synthesized intervals to a given query. A query result is a list of synthesized intervals sorted in the order of their degree of relevance 相似文献
7.
HweeHwa Pang Xuhua Ding Baihua Zheng 《The VLDB Journal The International Journal on Very Large Data Bases》2010,19(3):437-456
The top-k query is employed in a wide range of applications to generate a ranked list of data that have the highest aggregate scores
over certain attributes. As the pool of attributes for selection by individual queries may be large, the data are indexed
with per-attribute sorted lists, and a threshold algorithm (TA) is applied on the lists involved in each query. The TA executes
in two phases—find a cut-off threshold for the top-k result scores, then evaluate all the records that could score above the threshold. In this paper, we focus on exact top-k queries that involve monotonic linear scoring functions over disk-resident sorted lists. We introduce a model for estimating
the depths to which each sorted list needs to be processed in the two phases, so that (most of) the required records can be
fetched efficiently through sequential or batched I/Os. We also devise a mechanism to quickly rank the data that qualify for
the query answer and to eliminate those that do not, in order to reduce the computation demand of the query processor. Extensive
experiments with four different datasets confirm that our schemes achieve substantial performance speed-up of between two
times and two orders of magnitude over existing TAs, at the expense of a memory overhead of 4.8 bits per attribute value.
Moreover, our scheme is robust to different data distributions and query characteristics. 相似文献
8.
一种在KNN查询处理中预估剪枝阈值的方法 总被引:1,自引:0,他引:1
KNN查询是多媒体数据库管理系统中最具代表性的查询方式之一。与范围查询不同,KNN查询过程中缺乏固定的剪枝阈值。为达到剪枝的目的KNN算法使用保守的KNN距离剪枝,通常把到当前访问过的第K个最近点的距离作为剪枝阈值。传统的KNN查询处理算法在找到K个候选查询结果之前无法生成剪枝阈值,使得在此期间所有访问到的节点都被置入待访问节点队列。文中提出了在KNN查询处理中预估剪枝阈值的方法,该方法在找到K个候选查询结果前通过分析当前所访问过的页区域来预估剪枝阈值,试验表明使用预估剪枝阈值进行剪枝可有效缩短待访问节点队列的长度。 相似文献
9.
Qi Yang Weining Zhang Chengwen Liu Jing Wu Yu C. Nakajima H. Rishe N.D. 《Knowledge and Data Engineering, IEEE Transactions on》2001,13(6):884-901
In a fuzzy relational database where a relation is a fuzzy set of tuples and ill-known data are represented by possibility distributions, nested fuzzy queries can be expressed in the Fuzzy SQL language. Although it provides a very convenient way for users to express complex queries, a nested fuzzy query may be very inefficient to process with the naive evaluation method based on its semantics. In conventional databases, nested queries are unnested to improve the efficiency of their evaluation. In this paper, we extend the unnesting techniques to process several types of nested fuzzy queries. An extended merge-join is used to evaluate the unnested fuzzy queries. As shown by both theoretical analysis and experimental results, the unnesting techniques with the extended merge-join significantly improve the performance of evaluating nested fuzzy queries 相似文献
10.
11.
On Similarity Measures for Multimedia Database Applications 总被引:1,自引:1,他引:0
A multimedia database query consists of a set of fuzzy and boolean (or crisp) predicates, constants, variables, and conjunction,
disjunction, and negation operators. The fuzzy predicates are evaluated based on different media criteria, such as color,
shape, layout, keyword. Since media-based evaluation yields similarity values, results to such a query is defined as an ordered
set. Since many multimedia applications require partial matches, query results also include tuples which do not satisfy all
predicates. Hence, any fuzzy semantics which extends the boolean semantics of conjunction in a straight forward manner may
not be desirable for multimedia databases. In this paper, we focus on the problem of ‘given a multimedia query which consists of multiple fuzzy and crisp predicates, how to provide the user with a meaningful
overall ranking.’ More specifically, we study the problem of merging similarity values in queries with multiple fuzzy predicates. We describe
the essential multimedia retrieval semantics, compare these with the known approaches, and propose a semantics which captures
the retrieval requirements in multimedia databases.
Received 13 August 1999 / Revised 13 May 2000 / Accepted in revised form 26 July 2000 相似文献
12.
Krishnapuram R. Medasani S. Sung-Hwan Jung Young-Sik Choi Balasubramaniam R. 《Knowledge and Data Engineering, IEEE Transactions on》2004,16(10):1185-1199
A typical content-based image retrieval (CBIR) system would need to handle the vagueness in the user queries as well as the inherent uncertainty in image representation, similarity measure, and relevance feedback. We discuss how fuzzy set theory can be effectively used for this purpose and describe an image retrieval system called FIRST (fuzzy image retrieval system) which incorporates many of these ideas. FIRST can handle exemplar-based, graphical-sketch-based, as well as linguistic queries involving region labels, attributes, and spatial relations. FIRST uses fuzzy attributed relational graphs (FARGs) to represent images, where each node in the graph represents an image region and each edge represents a relation between two regions. The given query is converted to a FARG, and a low-complexity fuzzy graph matching algorithm is used to compare the query graph with the FARGs in the database. The use of an indexing scheme based on a leader clustering algorithm avoids an exhaustive search of the FARG database. We quantify the retrieval performance of the system in terms of several standard measures. 相似文献
13.
14.
Bokka V. Gurla H. Olariu S. Schwing J.L. Wilson L. 《Parallel and Distributed Systems, IEEE Transactions on》1997,8(1):13-24
Query processing is a crucial component of various application domains including information retrieval, database design and management, pattern recognition, robotics, and VLSI. Many of these applications involve data stored in a matrix satisfying a number of properties. One property that occurs time and again specifies that the rows and the columns of the matrix are independently sorted. It is customary to refer to such a matrix as sorted. An instance of the batched searching and ranking problem (BSR) involves a sorted matrix A of items from a totally ordered universe, along with a collection Q of queries. Q is an arbitrary mix of the following query types: for a search query qj , one is interested in an item of A that is closest to qj ; for a rank query qj one is interested in the number of items of A that are strictly smaller than qj. The BSR problem asks for solving all queries in Q. The authors consider the BSR problem in the following context: the matrix A is pretiled, one item per processor, onto an enhanced mesh of size √n×√n; the m queries are stored, one per processor, in the first m/√n¯ columns of the platform. Their main contribution is twofold. First, they show that any algorithm that solves the BSR problem must take at least Ω(max{logn, √m}) time in the worst case. Second, they show that this time lower bound is tight on meshes of size √n×√n enhanced with multiple broadcasting, by exhibiting an algorithm solving the BSR problem in Θ(max{logn, √m}) time on such a platform 相似文献
15.
16.
Ishfaq Ahmad Kamalakar Karlapalem Yu-Kwong Kwok Siu-Kai So 《Distributed and Parallel Databases》2002,11(1):5-32
A major cost in executing queries in a distributed database system is the data transfer cost incurred in transferring relations (fragments) accessed by a query from different sites to the site where the query is initiated. The objective of a data allocation algorithm is to determine an assignment of fragments at different sites so as to minimize the total data transfer cost incurred in executing a set of queries. This is equivalent to minimizing the average query execution time, which is of primary importance in a wide class of distributed conventional as well as multimedia database systems. The data allocation problem, however, is NP-complete, and thus requires fast heuristics to generate efficient solutions. Furthermore, the optimal allocation of database objects highly depends on the query execution strategy employed by a distributed database system, and the given query execution strategy usually assumes an allocation of the fragments. We develop a site-independent fragment dependency graph representation to model the dependencies among the fragments accessed by a query, and use it to formulate and tackle data allocation problems for distributed database systems based on query-site and move-small query execution strategies. We have designed and evaluated evolutionary algorithms for data allocation for distributed database systems. 相似文献
17.
基于关系数据库的模糊查询技术 总被引:2,自引:0,他引:2
樊新华 《计算机与数字工程》2009,37(10):149-152,156
在关系数据库中,SQL只能处理精确查询,而现实中存在许多模糊查询的问题。在模糊逻辑理论的基础上,提出了关系数据库的模糊查询思路,并详细地讨论了在数值和字符属性上的实现方法。实现方法不仅对数据库的查询进行了扩展,而且对实际系统的开发也有一定的借鉴作用。 相似文献
18.
Mumtaz Ahmad Ashraf Aboulnaga Shivnath Babu Kamesh Munagala 《The VLDB Journal The International Journal on Very Large Data Bases》2011,20(4):589-615
The typical workload in a database system consists of a mix of multiple queries of different types that run concurrently.
Interactions among the different queries in a query mix can have a significant impact on database performance. Hence, optimizing
database performance requires reasoning about query mixes rather than considering queries individually. Current database systems
lack the ability to do such reasoning. We propose a new approach based on planning experiments and statistical modeling to
capture the impact of query interactions. Our approach requires no prior assumptions about the internal workings of the database
system or the nature and cause of query interactions, making it portable across systems. To demonstrate the potential of modeling
and exploiting query interactions, we have developed a novel interaction-aware query scheduler for report-generation workloads.
Our scheduler, called QShuffler, uses two query scheduling algorithms that leverage models of query interactions. The first algorithm is optimized for workloads
where queries are submitted in large batches. The second algorithm targets workloads where queries arrive continuously, and
scheduling decisions have to be made online. We report an experimental evaluation of QShuffler using TPC-H workloads running
on IBM DB2. The evaluation shows that QShuffler, by modeling and exploiting query interactions, can consistently outperform
(up to 4x) query schedulers in current database systems. 相似文献
19.
在精确XML文档上的关键字查询方法的研究大多是基于LCA语义或者其变种语义(SLCA,ELCA等)开展的,将包含所有关键字的最紧致XML子树片段作为查询结果返回。但是这些基于LCA语义产生的查询结果中通常包含了大量的冗余信息,现实世界中存在着大量的不确定和模糊信息,因而如何从模糊XML文档中搜索到高质量的关键字查询结果是一个需要研究的问题。针对模糊XML文档上的关键字近似查询方法进行研究,通过引入最小连接树(MCT)的概念,提出在模糊XML文档上关键字查询的所有GDMCTs问题,并给出解决这一问题的基于栈的算法All fuzzy GDMCTs,该算法可以得到满足用户指定的子树大小阈值和可能性阈值条件的所有GDMCTs结果。实验表明,该算法在模糊XML文档上能够得到较高质量的关键字查询结果。 相似文献