Identifying New Directions in Database Performance Tuning

Database performance tuning is a complex and varied active research topic. With enterprise relational database management systems still reliant on the same set-based relational concepts that defined early data management products, the disparity between the object-oriented application development model and the object-relational database model, called the object-relational impedance mismatch problem, is addressed by techniques such as object-relational mapping (ORM). However, this has resulted in generally poor query performance for SQL developed by object applications and an irregular fit with cost-based optimisation algorithms, and leads to questions about the need for the relational model to better adapt to ORM-generated queries. This paper discusses database performance optimisation developments and seeks to demonstrate that current database performance tuning approaches need re-examination. Proposals for further work include exploring concepts such as dynamic schema redefinition; query analysis and optimisation modelling driven by machine learning; and augmentation or replacement of the cost-based optimiser model

Storage management and indexing in object-oriented database management systems

Ankara : The Department of Computer Engineering and Information Sciences and the Institute of Engineering and Sciences of Bilkent Univ., 1990.Thesis (Master's) -- Bilkent University, 1990.Includes bibliographical references leaves 76-77Storage management and indexing methods used in existing conventional database management systems are not appropriate for the object-oriented database management systems due to the distinctive features of the later systems. A model for storage management suitable for object- oriented database management systems is proposed in this thesis. It supports object identity, multiple inheritance, composite objects, a fine degree of granularity and schema evolution. An index provides fast access to data stored in files at the price of using additional storage space and an overhead in update operations. Work has been carried out on indexing and an indexing method for the object-oriented database systems is proposed. Identity and equality indexes are treated. Object identity and information hiding are provided. Schema changes are handled without affecting existing indexes. It is general enough to be applicable to most existing object-oriented database systems. The mapping of the proposed storage and indexing approaches into a relational database scheme is also presented.Al-Hajj, RedaM.S

An UML-XML-RDB Model Mapping Solution for Facilitating Information Standardization and Sharing

Abstract: To facilitate information standardization and sharing in Construction Industry, this paper presents a simple but effective approach that maps the UML (Unified Modeling Language) object-oriented information model related to a construction project to an XML schema, then to a Relational DataBase (RDB) schema. First of all, the mapping between UML model and XML schema is discussed since UML has been a popular tool to model the static structure and dynamic behaviors of the information and processes in a construction project, while XML has become a de-facto standard for information sharing and exchange. Then, a set of consistent rules for mapping from XML schema to RDB's Entity-Relational (E-R) model are studied and established since RDB has been the most popular choice for information management. The present study focuses on making the set of rules simple and easy-to-implement for most applications in construction industry. Finally, a mapping tool for automatically generating RDB schemas from XML Schemas is developed

Towards a metrics suite for object-relational mappings

Object-relational (O/R) middleware is frequently used in practice to bridge the semantic gap (the ‘impedance mismatch’) between object-oriented application systems and relational database management systems (RDBMSs). If O/R middleware is employed, the object model needs to be linked to the relational schema. Following the so-called forward engineering approach, the developer is faced with the challenge of choosing from a variety of mapping strategies for class associations and inheritance relationships. These mapping strategies have different impacts on the characteristics of application systems, such as their performance or maintainability. Quantifying these mapping impacts via metrics is considered beneficial in the context of O/R mapping tools since such metrics enable an automated and differentiated consideration of O/R mapping strategies. In this paper, the foundation of a metrics suite for objectrelational mappings and an initial set of metrics are presented

Performance Comparison of Hibernate and EclipseLink Technologies for Mapping an Object-Oriented Model to a Relational Database

Different tiers of modern applications are built using object-oriented programming for implementing business logic and the relational database model for data storage. To solve the impendence mismatch issue that arises between the object model and relational schema, various Object-Relational Mapping (ORM) tools have been designed. In this research, the performance of two open source ORM technologies, namely Hibernate and EclipseLink, is investigated. Hibernate is a well established middleware solution while EclipseLink, which stems from Oracle’s TopLink, is a new product on the persistence landscape. For the purpose of this research, a web-based application was developed and used as a test system. The performance test facilities were integrated into design of the application. The abstract layer introduced into application’s architecture with the Spring Data Access Object (DAO), made the system highly modular allowing easily switching between persistence technologies with no alterations in the rest of the application code

Towards a new hybrid approach for building document-oriented data warehouses

Schemaless databases offer a large storage capacity while guaranteeing high performance in data processing. Unlike relational databases, which are rigid and have shown their limitations in managing large amounts of data. However, the absence of a well-defined schema and structure in not only SQL (NoSQL) databases makes the use of data for decision analysis purposes even more complex and difficult. In this paper, we propose an original approach to build a document-oriented data warehouse from unstructured data. The new approach follows a hybrid paradigm that combines data analysis and user requirements analysis. The first data-driven step exploits the fast and distributed processing of the spark engine to generate a general schema for each collection in the database. The second requirement-driven step consists of analyzing the semantics of the decisional requirements expressed in natural language and mapping them to the schemas of the collections. At the end of the process, a decisional schema is generated in JavaScript object notation (JSON) format and the data loading with the necessary transformations is performed

Exposing the myth: object-relational impedance mismatch is a wicked problem

Addressing a problem of software integration is a fact of life for those involved in software development. The popularity of both object and relational technologies means that they will inevitably be used together. However, the combination of these two technologies introduces problems. These problems are referred to collectively as the object-relational impedance mismatch. A mismatch is addressed using one or more mapping strategies, typically embodied in a pattern. A strategy is concerned with correspondence between the schema of a relational database and an object-oriented program. Such strategies are employed in mapping tools such as Hibernate and TopLink, and reinforce the received wisdom that the problem of object-relational impedance mismatch has been solved. In this paper, we observe that it is not clear whether each strategy, as one possible solution, addresses the cause or a symptom of a mismatch. We argue that the problem is not tame and easily resolved; rather it is complex and wicked. We introduce a catalogue of problem themes that demonstrate the complex nature of the problem and provide a way both to talk about the problem and to understand its complexity. In the future, as software systems become more complex and more connected, it will be important to learn from past endeavours. Our catalogue of problem themes represents a shift, in thinking about the problem of object-relational impedance mismatch, from issues of implementation towards an analysis of cause and effect. Such a shift has implications for those involved in the design of current and future software architectures. Because we have questioned the received wisdom, we are now in a position to work toward an appropriate solution to the problem of object-relational impedance mismatch

Database independent Migration of Objects into an Object-Relational Database

This paper reports on the CERN-based WISDOM project which is studying the serialisation and deserialisation of data to/from an object database (objectivity) and ORACLE 9i.Comment: 26 pages, 18 figures; CMS CERN Conference Report cr02_01

Object-oriented querying of existing relational databases

In this paper, we present algorithms which allow an object-oriented querying of existing relational databases. Our goal is to provide an improved query interface for relational systems with better query facilities than SQL. This seems to be very important since, in real world applications, relational systems are most commonly used and their dominance will remain in the near future. To overcome the drawbacks of relational systems, especially the poor query facilities of SQL, we propose a schema transformation and a query translation algorithm. The schema transformation algorithm uses additional semantic information to enhance the relational schema and transform it into a corresponding object-oriented schema. If the additional semantic information can be deducted from an underlying entity-relationship design schema, the schema transformation may be done fully automatically. To query the created object-oriented schema, we use the Structured Object Query Language (SOQL) which provides declarative query facilities on objects. SOQL queries using the created object-oriented schema are much shorter, easier to write and understand and more intuitive than corresponding S Q L queries leading to an enhanced usability and an improved querying of the database. The query translation algorithm automatically translates SOQL queries into equivalent SQL queries for the original relational schema