HiLog as a platform for database languages
Data Engineering
Language features for interoperability of databases with schematic discrepancies
SIGMOD '91 Proceedings of the 1991 ACM SIGMOD international conference on Management of data
Querying object-oriented databases
SIGMOD '92 Proceedings of the 1992 ACM SIGMOD international conference on Management of data
Logical foundations of object-oriented and frame-based languages
Journal of the ACM (JACM)
The object database standard: ODMG 2.0
The object database standard: ODMG 2.0
SERF: ODMG-based generic re-structuring facility
SIGMOD '99 Proceedings of the 1999 ACM SIGMOD international conference on Management of data
Evolution and change in data management — issues and directions
ACM SIGMOD Record
On Efficiently Implementing SchemaSQL on an SQL Database System
VLDB '99 Proceedings of the 25th International Conference on Very Large Data Bases
Towards a Real Horn Clause Language
VLDB '88 Proceedings of the 14th International Conference on Very Large Data Bases
SchemaSQL - A Language for Interoperability in Relational Multi-Database Systems
VLDB '96 Proceedings of the 22th International Conference on Very Large Data Bases
OQL_SERF: an ODMG implementation of the template-based schema evolution framework
CASCON '98 Proceedings of the 1998 conference of the Centre for Advanced Studies on Collaborative research
Flattening the Metamodel for Object Databases
ADBIS '02 Proceedings of the 6th East European Conference on Advances in Databases and Information Systems
Schema Evolution in SQL-99 and Commercial (Object-)Relational DBMS
FoMLaDO/DEMM 2000 Selected papers from the 9th International Workshop on Foundations of Models and Languages for Data and Objects, Database Schema Evolution and Meta-Modeling
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Many applications in Object Databases (ODB), for example, schema management tools, CASE tools, database development tools and integration wrappers, need extensive queries over both application data as well as metadata. However queries over metadata via OQL, a de-facto standard for object query languages defined for the ODMG 2.0 Object Model, are tied to low-level implementation details of the underlying schema repository of the database system. Hence, they are neither portable nor easily usable, requiring the application developer to have detailed knowledge of the proprietary structure of the schema repository. In this paper, we propose an extension of OQL, called MetaOQL, to address this limitation. Our proposition of MetaOQL offers several benefits: (1) it is a natural extension of OQL in terms of both its syntax and semantics; (2) it removes the dependency of metadata queries on the particular schema repository, hence providing uniformity and portability of metadata queries across different ODBs; (3) it supports transparent navigation over the metadata thus offering ease of use; (4) unlike OQL, it hides metadata querying details from the users hence the queries can be simplified and more easy to read and understand. We have also investigated implementation strategies for MetaOQL. In particular, we propose a translation strategy from MetaOQL to OQL as a preferable solution compared to development of a special-purpose MetaOQL processor. The translation strategy offers the advantage that the MetaOQL queries can be retargeted to work on top of any existing ODB engine equipped with OQL with minimal effort. Furthermore, all OQL query optimization strategies can thus still be brought to bear in our extended system.