Object-relational Mapping Tools Research Articles

Comparing the Performance of the Object-Relational Mapping Program-ming Frameworks Available in Java

The paper concerns a performance evaluation of selected object-relational mapping tools. This work is intended to assist software architects in determining which of the analyzed libraries will be the optimal choice for use in a specific project. The work includes the comparison of Hibernate ORM, EclipseLink, Apache OpenJPA and DataNucleus libraries from the theoretical and practical point of view. Each of the examined tools has been described according to criteria allowing to distinguish the most important features influencing communication with relational databases. These features will then be compared on a practical level by examining the behavior of the test applications. In terms of performance, the Apache OpenJPA library turned out to be the best, but in terms of configuration and availability it significantly differs from other libraries. This was caused by an unintuitive configuration and poor documentation of the technology. In this respect, the Hibernate library definitely dominated, the configuration of which with the Spring programming framework was simple and intuitive, and the documentation was rich and supported by an extensive community of programmers using it.

Investigating the Effects of Object-Relational Impedance Mismatch on the Efficiency of Object-Relational Mapping Frameworks

The object-relational impedance mismatch (ORIM) problem characterises differences between the object-oriented and relational approaches to data access. Queries generated by object-relational mapping (ORM) frameworks are designed to overcome ORIM difficulties and can cause performance concerns in environments which use object-oriented paradigms. The aim of this paper is twofold, first presenting a survey of database practitioners on the effectiveness of ORM tools followed by an experimental investigation into the extent of operational concerns through the comparison of ORM-generated query performance and SQL query performance with a benchmark data set. The results show there are perceived difficulties in tuning ORM tools and distrust around their effectiveness. Through experimental testing, these views are validated by demonstrating that ORMs exhibit performance issues to the detriment of the query and the overall scalability of the ORM-led approach. Future work on establishing a system to support the query optimiser when parsing and preparing ORM-generated queries is outlined.

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 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). This, compounded with changes in the way data is produced, stored and managed can result in generally poor query performance for SQL produced by object-oriented 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 a more diverse set of queries. This paper discusses existing database performance optimisation techniques and approaches and makes the argument that current database performance tuning approaches need revisiting to support queries developed through ORM tools. This paper also introduces our current research, which includes exploring concepts such as dynamic schema redefinition; query analysis and optimisation modelling driven by machine learning; and augmentation of the cost-based optimiser model.

Integr8: Enhanced Inter-Operability of European Molecular Biology Databases

The increasing production of molecular biology data in the post-genomic era, and the proliferation of databases that store it, require the development of an integrative layer in database services to facilitate the synthesis of related information. The solution of this problem is made more difficult by the absence of universal identifiers for biological entities, and the breadth and variety of available data. Integr8 was modelled using UML (Universal Modelling Language). Integr8 is being implemented as an n-tier system using a modern object-oriented programming language (Java). An object-relational mapping tool, OJB, is being used to specify the interface between the upper layers and an underlying relational database. The European Bioinformatics Institute is launching the Integr8 project. Integr8 will be an automatically populated database in which we will maintain stable identifiers for biological entities, describe their relationships with each other (in accordance with the central dogma of biology), and store equivalences between identified entities in the source databases. Only core data will be stored in Integr8, with web links to the source databases providing further information. Integr8 will provide the integrative layer of the next generation of bioinformatics services from the EBI. Web-based interfaces will be developed to offer gene-centric views of the integrated data, presenting (where known) the links between genome, proteome and phenotype.