AnyQuery:网格环境下基于服务的分布式查询处理系统

AnyQuery是一种适用于网格环境、基于服务的分布式查询处理系统，使用统一的数据格式（可扩展标记语言）来表示和传输数据，所有组成模块以网格服务的形式实现，网格服务之间通过标准的接口进行通信．这种接口和实现分离技术屏蔽了不同数据库及其运行节点的差异，为用户提供一致的虚拟关系数据视图和分布式数据查询支持．在分析和研究已有的并行数据库和分布式数据库查询技术的基础上，AnyQuery提出和实现了一种适用于动态网格环境的分布式查询计划生成和执行算法，该算法能够根据网格环境中各节点及其连接网络的实际情况确定查询计划，支持跨数据库的连接查询．基于Globus 3．0开发了AnyQuery的原型系统，性能测试表明该系统具有较好的可扩展性，尤其适合计算密集型的复杂查询．     

PICQUERY: a high level query language for pictorial databasemanagement

A reasonably comprehensive set of data accessing and manipulation operations that should be supported by a generalized pictorial database management system (PDBMS) is proposed. A corresponding high-level query language, PICQUERY, is presented and illustrated through examples. PICQUERY has been designed with a flavor similar to QBE as the highly nonprocedural and conservational language for the pictorial database management system PICDMS. PICQUERY and a relational QBE-like language would form the language by which a user could access conventional relational databases and at the same time pictorial databases managed by PICDMS or other robust PDBMS. This language interface is part of an architecture aimed toward data heterogeneity transparency over pictorial and nonpictorial databases     

一种基于SQL的层次查询方法

关系型数据库管理系统不适合表达层次模型问题,标准的SQL语言无法满足复杂的层次查询要求,但有许多实际应用系统,其结构和查询要求都呈现很强的层次特征。本文提出了一种在ORACLE DBMS环境下,利用C和SQL语言实现的层次查询方法,可广泛应用于工程数据管理信息系统的设计过程。     

An interface between object-oriented databases and relational databases

Currently relational databases are widely used, while object-oriented databases are emerging as a new generation of database technology. This paper presents a methodology to provide effective sharing of information in object-oriented databases and relational databases. The object-oriented data model is selected as a common data model to build an integrated view of the diverse databases. An object-oriented query language is used as a standard query language. A method is developed to transform a relational data definition to an equivalent object-oriented data definition and to integrate local data definitions. Two distributed query processing methods are derived. One is for general queries and the other for a special class of restricted queries. Using the methods developed, it is possible to access distributed object-oriented databases and relational databases such that the locations and the structural differences of the databases are transparent to users.     

RDF查询语言到SQL语言的转换原理及其实现方法

RDF查询语言的优点是具有语义性，缺点是对于海量信息的存储和查找的效率都很低．而关系数据库对海量信息的存储和查找的效率皆很高，但是其查询语言SQL却缺乏语义信息．为了使信息查询既有RDF的语义性又有关系数据库的高性能，提出将RDF查询语言到SQL语言的转换原理，并在此基础上实现一个对用户透明的、建立在关系数据库之上的RDF查询引擎．其优点是：可以利用关系数据库来存储和查询RDF信息，提高其海量存储和查找效率；对存储在不同的关系数据库中的关系数据，能够利用RDF的查找特性进行异质数据库之间的信息交换及信息融合．     

VISIONARY: a Viewpoint-based Visual Language for Querying Relational Databases

The adoption of a visual interface can simplify the query formulation process in DBMSs by enabling naive users to interact with a friendly environment. In this work, we propose a visual query language based on a diagrammatic paradigm, used for both data and query representation. The external data model is called vision and is made up of the visual primitives of concept and association. The external query model is based on the definition of a viewpoint, which is a perspective for accessing data defined dynamically by selecting a concept of primary interest. Internally, the data model is relational and the query language is SQL. An intermediate graph-based model ensures consistent mapping between the visual and the relational worlds. Our language has been implemented within a tool which can be mounted on top of any relational DBMS supporting ODBC. The system has been tested with naive users; the results of the experiment are reported and compared with those obtained with other visual languages.     

Querying fuzzy relational databases through fuzzy domain calculus

In this paper we present a definition of a domain relational calculus for fuzzy relational databases using the GEFRED model as a starting point. It is possible to define an equivalent fuzzy tuple relational calculus and consequently we achieve the two query language levels that Codd designed for relational databases but these are extended to fuzzy relational databases: Fuzzy relational algebra (defined in the GEFRED model) and the fuzzy relational calculus which is put forward in this paper. The expressive power of this fuzzy relational calculus is demonstrated through the use of a method to translate any algebraic expression into an equivalent expression in fuzzy domain relational calculus. Furthermore, we include a useful system so that the degree to which each value has satisfied the query condition can be measured. Some examples are also included in order to clarify the definition. ©1999 John Wiley & Sons, Inc.     

Fuzzy database query languages and their relational completenesstheorem

Two fuzzy database query languages are proposed. They are used to query fuzzy databases that are enhanced from relational databases in such a way that fuzzy sets are allowed in both attribute values and truth values. A fuzzy calculus query language is constructed based on the relational calculus, and a fuzzy algebra query language is also constructed based on the relational algebra. In addition, a fuzzy relational completeness theorem such that the languages have equivalent expressive power is proved     

Visual query languages to design complex queries: a systematic literature review

Software and Systems Modeling - Structured query language (SQL) is a widely used language for accessing both relational and non-relational databases. SQL is the standard form of access in...     

基于BaseX数据库的OWL本体存储查询研究

针对目前基于关系型数据库等存储模式的本体存储查询效率较低的情况,提出使用XML数据库BaseX进行本体的存储,并设计了相应的本体存储查询架构。在对BaseX存储结构与接口的研究基础上,实现对OWL本体的存储。利用BaseX的查询接口和XQuery查询语言对OWL本体进行检索,在建立推理规则库基础上,实现本体查询扩展与推理。实验将提出的存储查询方法与基于关系型数据库的存储查询方法进行对比,验证了提出的方法具备高效的存储查询性能,同时具备本体查询的推理能力。     

Efficiently Querying Large XML Data Repositories: A Survey

Extensible markup language (XML) is emerging as a de facto standard for information exchange among various applications on the World Wide Web. There has been a growing need for developing high-performance techniques to query large XML data repositories efficiently. One important problem in XML query processing is twig pattern matching, that is, finding in an XML data tree D all matches that satisfy a specified twig (or path) query pattern Q. In this survey, we review, classify, and compare major techniques for twig pattern matching. Specifically, we consider two classes of major XML query processing techniques: the relational approach and the native approach. The relational approach directly utilizes existing relational database systems to store and query XML data, which enables the use of all important techniques that have been developed for relational databases, whereas in the native approach, specialized storage and query processing systems tailored for XML data are developed from scratch to further improve XML query performance. As implied by existing work, XML data querying and management are developing in the direction of integrating the relational approach with the native approach, which could result in higher query processing performance and also significantly reduce system reengineering costs.     

The aditi deductive database system

Deductive databases generalize relational databases by providing support for recursive views and non-atomic data. Aditi is a deductive system based on the client-server model; it is inherently multi-user and capable of exploiting parallelism on shared-memory multiprocessors. The back-end uses relational technology for efficiency in the management of disk-based data and uses optimization algorithms especially developed for the bottom-up evaluation of logical queries involving recursion. The front-end interacts with the user in a logical language that has more expressive power than relational query languages. We present the structure of Aditi, discuss its components in some detail, and present performance figures.     

Example-based graphical database query languages

Several user-friendly graphical database query languages that let users formulate a query by specifying a graphically aided example on the screen are compared. One of the earliest such languages, M.M. Zloof's (1977) Query-by-Example, is described. Other languages discussed are Aggregates-by-Example, Summary-Table-by-Example, and Query-by-Statistical-Relational-Table for statistical and scientific databases; Time-by-Example for historical databases; Generalized-Query-by-Example for relational, network, and hierarchical databases; Office-by-Example, Formanager, the Natural Forms Query Language, and System-for-Business-Automation for office environments; and Picquery and Query-by-Pictorial-Example for pictorial (image) databases. The basic features, query specification and interpretation, object manipulation, query language constructs, and query processing techniques used in each of the languages are discussed     

Using object deputy model to prepare data for data warehousing

Providing integrated access to multiple, distributed, heterogeneous databases and other information sources has become one of the leading issues in database research and the industry. One of the most effective approaches is to extract and integrate information of interest from each source in advance and store them in a centralized repository (known as a data warehouse). When a query is posed, it is evaluated directly at the warehouse without accessing the original information sources. One of the techniques that this approach uses to improve the efficiency of query processing is materialized view(s). Essentially, materialized views are used for data warehouses, and various methods for relational databases have been developed. In this paper, we first discuss an object deputy approach to realize materialized object views for data warehouses which can also incorporate object-oriented databases. A framework has been developed using Smalltalk to prepare data for data warehousing, in which an object deputy model and database connecting tools have been implemented. The object deputy model can provide an easy-to-use way to resolve inconsistency and conflicts while preparing data for data warehousing, as evidenced by our empirical study.     

Hybrid query execution engine for large attributed graphs

Graphs are widely used for modeling complicated data such as social networks, bibliographical networks and knowledge bases. The growing sizes of graph databases motivate the crucial need for developing powerful and scalable graph-based query engines. We propose a SPARQL-like language, G-SPARQL, for querying attributed graphs. The language enables the expression of different types of graph queries that are of large interest in the databases that are modeled as large graph such as pattern matching, reachability and shortest path queries. Each query can combine both structural predicates and value-based predicates (on the attributes of the graph nodes/edges). We describe an algebraic compilation mechanism for our proposed query language which is extended from the relational algebra and based on the basic construct of building SPARQL queries, the Triple Pattern. We describe an efficient hybrid Memory/Disk representation of large attributed graphs where only the topology of the graph is maintained in memory while the data of the graph are stored in a relational database. The execution engine of our proposed query language splits parts of the query plan to be pushed inside the relational database (using SQL) while the execution of other parts of the query plan is processed using memory-based algorithms, as necessary. Experimental results on real and synthetic datasets demonstrate the efficiency and the scalability of our approach and show that our approach outperforms native graph databases by several factors.     

WebFindIt: an architecture and system for querying Web databases

The Web offers a single user interface to data sharing across heterogeneous and autonomous databases, but it was not designed to handle the rigid DBMS protocols and data formats used by relational and object-oriented databases. WebFindIt is an ongoing project to develop the database equivalent of the World Wide Web-namely, a World Wide Database-through a middleware infrastructure for describing, locating, and accessing data from any kind of Web-accessible database. A special-purpose language, Web-Tassili, supports the definition and manipulation of middleware constructs for organizing the information space. An implementation of WebFindIt combines Java, CORBA and database technologies     

RASES: A database supported framework for structured model base management

Structured management of model base has placed demands on some kind of computer based frameworks with highly structured formalisms. This paper proposes a new framework, called the relational algebraic system entity structure (RASES), which is based on the system entity structure (SES) formalism and the relational algebra (RA) formalism. These formalisms provide a conceptual basis for the structured model base management. Within the framework, structural knowledge of a system is represented in a hierarchical structure and saved in a database. Furthermore, several operations can be formulated in terms of relational algebra which can be coded in a standard query language such as the SQL. The framework can be easily implemented on, and fully utilize the functionality of, relational database management system (RDBMS). With the help of the implemented framework, simulation models can be systematically synthesized from the models in the model base through the following processes. First, a family of hierarchical structures of a system is organized in the form of entity structure by the entity structuring process. Then, candidate models of the system which meet design objectives are synthesized from the entity structure through the pruning process. Finally, designers can conduct appropriate experiment with the models for design verification and performance measure.     

A database of groups of prime-power order

The design, implementation and performance of TwoGroups, a deductive database for the 58,761 groups of order 2ⁿ, (n ≤ 8), is described. The system is implemented in NU-Prolog, a Prolog system with built-in functions for creating and using deductive databases. TwoGroups has a set-theoretic query language, which provides users with a familiar notation to access the data. The paper describes the data and its representation, the set-theoretic query language, its translator and optimiser, and the experiments on the performance of the database.