Migrating Relational Databases Into Object-based and XML Databases

Download or read book Migrating Relational Databases Into Object-based and XML Databases written by Abdelsalam Maatuk and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Rapid changes in information technology, the emergence of object-based and WWWapplications, and the interest of organisations in securing benefits from new technologies have made information systems re-engineering in general and database migrationin particular an active research area. In order to improve the functionality and performance of existing systems, the re-engineering process requires identifying and understanding all of the components of such systems. An underlying database is one of themost important component of information systems. A considerable body of data isstored in relational databases (RDBs), yet they have limitations to support complexstructures and user-defined data types provided by relatively recent databases such asobject-based and XML databases. Instead of throwing away the large amount of datastored in RDBs, it is more appropriate to enrich and convert such data to be used bynew systems. Most researchers into the migration of RDBs into object-based/XMLdatabases have concentrated on schema translation, accessing and publishing RDBdata using newer technology, while few have paid attention to the conversion of data, and the preservation of data semantics, e.g., inheritance and integrity constraints. In addition, existing work does not appear to provide a solution for more than onetarget database. Thus, research on the migration of RDBs is not fully developed. Wepropose a solution that offers automatic migration of an RDB as a source into therecent database technologies as targets based on available standards such as ODMG3.0, SQL4 and XML Schema. A canonical data model (CDM) is proposed to bridgethe semantic gap between an RDB and the target databases. The CDM preserves andenhances the metadata of existing RDBs to fit in with the essential characteristics ofthe target databases. The adoption of standards is essential for increased portability, flexibility and constraints preservation. This thesis contributes a solution for migrating RDBs into object-based and XMLdatabases. The solution takes an existing RDB as input, enriches its metadata representation with the required explicit semantics, and constructs an enhanced relational schema representation (RSR). Based on the RSR, a CDM is generated whichis enriched with the RDB's constraints and data semantics that may not have beenexplicitly expressed in the RDB metadata. The CDM so obtained facilitates bothschema translation and data conversion. We design sets of rules for translating theCDM into each of the three target schemas, and provide algorithms for convertingRDB data into the target formats based on the CDM. A prototype of the solution has been implemented, which generates the three targetdatabases. Experimental study has been conducted to evaluate the prototype. Theexperimental results show that the target schemas resulting from the prototype andthose generated by existing manual mapping techniques were comparable. We havealso shown that the source and target databases were equivalent, and demonstratedthat the solution, conceptually and practically, is feasible, efficient and correct.