Database computers are special-purpose storage and processing devices which are intended to relieve the database management (software) systems running on the general-purpose computers and provide improved storage and processing capabilities (via hardware) for the existing and new database application. However, to support existing database applications, two steps must be followed. First, the existing database must be transformed into the storage format of the new database computer. This one-time tranformation, known as database transformation, is required to preserve the semantics of the database and to take advantage of the advanced hardware features of the new computer. Second, the database sublanguage used in the existing application programs must be supported in real time by the new database computer so that application programs may be executed in the new environment without the need of program conversion. Such real-time translation of sublanguage calls to the instructions of the new database computer, known as query translation, must be straightforward with minimal software support.