Exploring performance issues for a clinical database organized using an entity-attribute-value representation

• Published in: Journal of the American Medical Informatics Association : JAMIA 2000-09, Vol.7 (5), p.475-487
• Main Authors: Chen, R S, Nadkarni, P, Marenco, L, Levin, F, Erdos, J, Miller, P L
• Format: Article
• Language: English
• Subjects: Database Management Systems; Databases as Topic - organization & administration; Databases, Factual; Information Storage and Retrieval - methods; Microbiology; Original Investigations; Pilot Projects
• ISSN: 1067-5027; 1527-974X
• DOI: 10.1136/jamia.2000.0070475

The entity-attribute-value representation with classes and relationships (EAV/CR) provides a flexible and simple database schema to store heterogeneous biomedical data. In certain circumstances, however, the EAV/CR model is known to retrieve data less efficiently than conventionally based database schemas. To perform a pilot study that systematically quantifies performance differences for database queries directed at real-world microbiology data modeled with EAV/CR and conventional representations, and to explore the relative merits of different EAV/CR query implementation strategies. Clinical microbiology data obtained over a ten-year period were stored using both database models. Query execution times were compared for four clinically oriented attribute-centered and entity-centered queries operating under varying conditions of database size and system memory. The performance characteristics of three different EAV/CR query strategies were also examined. Performance was similar for entity-centered queries in the two database models. Performance in the EAV/CR model was approximately three to five times less efficient than its conventional counterpart for attribute-centered queries. The differences in query efficiency became slightly greater as database size increased, although they were reduced with the addition of system memory. The authors found that EAV/CR queries formulated using multiple, simple SQL statements executed in batch were more efficient than single, large SQL statements. This paper describes a pilot project to explore issues in and compare query performance for EAV/CR and conventional database representations. Although attribute-centered queries were less efficient in the EAV/CR model, these inefficiencies may be addressable, at least in part, by the use of more powerful hardware or more memory, or both.