MULTIDATABASE GLOBAL QUERY OPTIMIZATION

Data requests ro mulriaiztabase (MDBSs) are posed through non-procedural languages such as SQL and for a global data request optimization must be performed to achieve good system performance. However, the issues are ofren complicated in multidatabases, due to addirional issues arising because of the autonomy and heterogeneity restrictions of the independent local DBMSs. The data translation problem between various local systems can be observed at the schema level and at the instance level. We have identified the need for a domain translation table in mulridatabase query processing and discuss methods of implementing it. Some observations about multidatabase inter-site joins are made and fou