Each department of an enterprise has built its database independently. But the need of environment integration arises to access all databases of an enterprise. Recently, many database systems are built with client/server model. The database middleware system is suggested to make a client access a server among the multi servers. But the global query with a globl operation like join operation is not supported by the database middleware system.
In this thesis, We design a global query processor by which the users can exploit all distributed databases regardless knowing any information about them. And we reorganize this query processor with the existing database middleware system. For these global query processor, we also propose a gather-and-process strategy which is appropriate to the database middleware system. This strategy first gathers the data needed for a global operation from server systems, and it processes the global operation over the gathered data. To implement the reorganized global query processor, we implement a query preprocesor which splits a global query into local queries for each servers and generates a query for a global operation
