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Volume 35, Number 2, 1996
Object technology |
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Table of contents:  HTML |
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Copyright info |
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Storing and using objects in a relational database |
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by B. Reinwald, T. J. Lehman, H. Pirahesh, and V. Gottemukkala |
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In today's heterogeneous development environments,
application programmers have the responsibility to segment their
application data and to store those data in different types of stores.
That means relational data will be stored in RDBMSs (relational
database management systems), C++ objects in OODBMSs (object-oriented
database management systems), SOM (System Object Model) objects in OMG
(Object Management Group) persistent stores, and OpenDoc™
or OLE™ (Object Linking and Embedding) compound documents in
document files. In addition, application programmers must deal with
multiple server systems with different query languages as well as large
amounts of heterogeneous data. This paper describes SMRC (shared
memory-resident cache), an RDBMS extender that provides the ability to
store objects created in external type systems like C++ or SOM in a
relational database, coresident with existing relational or other
heterogeneous data. Using SMRC, applications can store and retrieve
objects via SQL (structured query language), and invoke methods on the
objects, without requiring any modifications to the original object
definitions. Furthermore, the stored objects fully participate in all
the characteristic features of the underlying relational database,
e.g., transactions, backup, and authorization. SMRC is implemented on
top of IBM's DB2® Common Server for AIX®
relational database
system and heavily exploits the DB2 user-defined types (UDTs),
user-defined functions (UDFs), and large objects (LOBs) technology. In
this paper, the C++ type system is used as a sample external type
system to exemplify the SMRC approach, i.e., storing C++ objects in
relational databases. Similar efforts are required for SOM or OLE
objects.
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