Heterogeneous Database Query Optimization in DB2 Universal DataJoiner
Shivakumar Venkataraman, Tian Zhang · 1998
DataJoiner (DJ) is a heterogeneous database system that provides a single database image of multiple databases. It provides transparent access to tables at remote databases through user defined aliases (nicknames) that can be accessed as if they were local tables. DJ is also a fully functional relational database system. A couple of salient features of the DataJoiner query optimizer are: (1) A query submitted to DataJoiner is optimized using a cost model that takes into account the remote optimizer’s capabilities in addition to the remote query processing capabilities and (2) If a remote database system lacks some functionality (eg: sorting), DataJoiner compensates for it. In this paper, we present the design of the Data-joiner query optimizer.