Databases Reference
In-Depth Information
3.
If the matching record is not found for 1
≤
i
≤
n,
overwrite the record
(n)
with the referrer ID and its reference count 1.
The above data structure can be duplicated to achieve better performance. The
new structure records the PE ID and the references
to
the PE in a manner that is
symmetric to the previous structure. By using this information, the object relocation
can successfully decrease the external references.
Although the above-described scheme is still an approximation, the performance
has been reported to be improved
8,
11)
.
Future Research Issues
The object-parallel approach for parallel database applications has several
advantages over conventional data-parallel approaches. However, a number of
questions remain that must be answered in future studies.
First, the interactions among the object relocation strategies should be
investigated. When studying the object relocation strategies, each strategy was
tested separately. If applied at the same time, however, some objects may experience
conflicting relocation operations caused by multiple strategies, and may be relocated
in an improper manner.
Second, a new generation of high-performance parallel machines should be
considered. Due to recent advances in hardware technology, a symmetric
multiprocessor (SMP) has become a reasonable choice for a PE. An SMP cluster,
SMPs connected via a high-speed network, is already a feasible solution for a
high-performance database server. In this configuration, the object reference
mechanism and the object relocation mechanisms may require revisions.
4
An object database management system on a workstation
cluster
ShusseUo is a scalable distributed and parallel object database management
system
17)
for a
workstation cluster
. The object database system is effective for
advanced applications such as multimedia databases, and engineering databases,
because complex-structured data can be represented naturally using an object
model, such as
OID
or
relationship,
which are given by an object database. Client
programs share a database and often send a request to a server concurrently. A
workstation cluster is a set of distributed computers connected by computer
network(s). Database server programs run on all sites of a workstation cluster,
and the workstation cluster is expected to act as one parallel database machine.
An ideal parallel machine has linear scalability as the number of sites increases.
Architecture
ShusseUo is an ODMG3.0-compliant object-oriented database system. The Ob
ject Database Management Group (ODMG) produced a standard for object
