Database Reference
In-Depth Information
•
Mapping between the two different system catalogs so that users of
one DBMS (Oracle) can access all files from the other DBMS (DB2)
•
Mapping between the two different sets of data used
•
Resolution of semantic mismatches across the two systems
(e.g. attribute
Employee.Empno
in a DB2 table may map to
Empl.Emp#
in an Oracle table)
•
Resolution of transaction management issues such as data
locking, updates, commit and rollback
•
Resolution of security and accessibility issues across the two
different systems
Figure 22-2.
Illustrating the Function of a Database Gateway
By way of example, Oracle operates a very sophisticated gateway system that
allows connectivity to other non-Oracle databases either directly through its gateway,
or indirectly through ODBC (see [Oracle, 2008]). Among the many features of the Oracle
gateway system are the following:
•
Location independence and transparency
•
Data-type translations between Oracle and non-Oracle systems
•
Data dictionary between Oracle and non-Oracle systems
•
Read/write access
•
Support for large objects (LOBs)
•
Support for non-Oracle stored procedures
•
Transmission of pass-through SQL between Oracle and non-
Oracle system
•
Data encryption services
