Moss L.T., Atre S. Business intelligence roadmap: The complete project lifecycle for decision-support applications
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DBMS Gateways
DMBS gateways, a form of middleware, are generally required to connect the
different network architectures of desktop computers, remote clients, or small
enterprise servers to industrial-strength enterprise servers.
Gateways fall into four major categories.
Point-to-point gateways provide access to only one type of DBMS. Vendors
market each point-to-point gateway as a different product. A point-to-point
gateway is easy to implement because it handles only one DBMS at a time. It is
also a less expensive solution compared with the other three gateway solutions.
However, when the organization requires access to multiple DBMSs, it needs
multiple gateways. In that case, point-to-point gateways may not be a less
expensive solution than using a universal gateway.
1.
Gateways that can be used universally provide access to different types of
databases on various platforms. Universal gateways require extensive effort to
implement and maintain. As a result, these gateways become expensive.
2.
Gateways using Structured Query Language (SQL) can access only "real"
relational databases, not simulated ones. The SQL gateway translates the client
request into the native SQL syntax used by the server's relational DBMS.
3.
Gateways based on application programming interfaces (APIs) are driven by
vendor specifications. One of the major gateways of this type is open database
connectivity (ODBC). A number of ODBC vendors provide drivers for accessing
databases residing on various servers.
4.
Organizational data is distributed across multiple DBMS platforms, cooperating
across a network with different instruction sets from multiple vendors. ODBC-enabled
applications can access multiple distributed data sources concurrently via ODBC's
common interface approach (Figure 2.4).
Figure 2.4. ODBC-Enabled Applications
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Modules called database drivers can be added to link the applications to the DBMS of
their choice. Database drivers consist of dynamic link libraries (DLLs) that
applications can invoke on demand.
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The DBMS Platform
The database infrastructure changes with the size of the BI decision-support
environment, which in turn influences the selection of the DBMS, as shown in Figure
2.5. A small departmental data mart application may reside on a local file server, but
a larger BI application may need the infrastructure support of an enterprise server,
and very large enterprise-wide BI solutions may need to use a mainframe.
Figure 2.5. Database Infrastructures
Criteria for Selecting a DBMS
The following functions are important and necessary attributes of a DBMS for
handling the workload of a large BI target database or very large database (VLDB):
Degree of parallelism in handling queries and data loads
Intelligence in handling dimensional data models and optimizers
Database scalability
Internet integration
Availability of advanced index schemes
Replication on heterogeneous platforms
Unattended operations
A DBMS is a sophisticated piece of software and consists of a number of features that
need to be evaluated. Features to look for in a DBMS for BI applications are listed
below.
Network support provided by the DBMS should be compatible with the
organization's data communications standards.
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Dimensional capability in the form of seamless support for fast and easy loading
and maintenance of precompiled summaries is important.
Adequate state-of-the-art triggers and stored procedures can be used as "event
alerters," which trigger an action in response to a given set of circumstances.
Administrative support features should provide for:
- Maintenance of consistent historical data
- Support for archiving (e.g., dropping the oldest week's data when
adding the data for a new week)
- Controls for implementing resource limits to display a warning when a
query that consumes excessive resources is about to be terminated
- Workload tracking and tuning mechanisms
- Careful monitoring of activity and resource utilization
Location transparency across the network must allow the access and analysis
tools to retrieve data from multiple BI target databases from a single
workstation.
Future usage explosion must be supported by:
- Effective caching and sharing of data to minimize input/output (I/O)
bottlenecks
- Effective management of task switching while running many queries
concurrently
- Compatibility with multiple processors
Scalability requires that the DBMS has the capability to support:
- Advanced functions for sorting and indexing
- Fault tolerance for uninterrupted processing
- Uninterrupted maintenance operations, such as unload, backup, and
restore
- Checkpoints, recovery, and rapid restart of interrupted operations
Query performance optimization should address aspects of query processing
(such as JOINs, sorting, and grouping) that require intensive use of the central
processing unit (CPU).
Load process and performance must address:
- Data obtained directly from a variety of feeds, including disk files,
network feeds, mainframe channel connections, and magnetic tapes
- Complete data loading and preparation, including format conversion,
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integrity enforcement, and indexing
The security system must support unique passwords, password protection, and
the authorization constraints necessary for specific persons and for specific
tables of the database. The system administrator should provide restricted
access to the views and virtual tables.
The data dictionary should feed into a meta data repository, and the database
objects should be linked to all data objects described in the enterprise logical
data model.
Selecting and reevaluating the appropriate hardware, middleware, and DBMS
components of the technical infrastructure are some of the most important activities
on BI projects because they ensure the continued scalability and high performance of
the BI applications.
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Technical Infrastructure Evaluation Activities
The technical infrastructure evaluation activities do not need to be performed
linearly. Figure 2.6 indicates two activities that can be performed concurrently. The
list below briefly describes the activities associated with Step 2, Section A, Technical
Infrastructure Evaluation.
Assess the existing platform.
Review the existing platform in terms of hardware, middleware, DBMS, and
tools. It is important to evaluate the interdependence of the tools for their
various purposes, such as the interdependence between a multidimensional
reporting tool and an ad hoc querying tool. In addition, review the existing
network architecture. One of the biggest bottlenecks today, especially in
organizations with decentralized applications, is the lack of bandwidth coupled
with a limited capacity for network growth.
1.
Evaluate and select new products.
After assessing the existing platforms, identify which types of new hardware,
software, or networking components you must acquire. If the existing hardware
platform appears to be sufficient, be sure to determine that it will be able to
provide the productivity and performance the organization expects from it.
Engage business representatives and stakeholders in the decision-making
process by including them in peer reviews during the selection process.
2.
Write the technical infrastructure assessment report.
Compile all findings about the existing platform into a report. Explain the
strengths and weaknesses of the current hardware, middleware, DBMS, and
tools, and provide a list of missing technical infrastructure components
necessary to meet the project requirements.
3.
Expand the current platform.
Once you have determined which new products need to be acquired, you can
begin the process of evaluating, selecting, ordering, installing, and testing
them.
4.
Figure 2.6. Technical Infrastructure Evaluation Activities
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Deliverables Resulting from These Activities
Technical infrastructure assessment report
This report should itemize the scalability and limitations of the hardware,
middleware, DBMS, and tool platform and should cover the following items:
- Servers
- Client workstations
- Operating systems
- Middleware (especially DBMS gateways)
- Custom interfaces
- Network components and bandwidth
- DBMS functionality and utilities (backup and recovery, performance
monitoring)
- Development tools such as computer aided software engineering (CASE)
and ETL tools
- Access and analysis tools such as OLAP tools and report writers
- Meta data repository
Include a gap analysis section and provide recommendations for
upgrading the platform. Incorporate the product evaluation and selection
results, listing the weighted requirements and the product features you
evaluated. The product and vendor evaluation and selection process is
described in more detail in Step 10, Meta Data Repository Design.
1.
Installation of selected products
If you identified new products to purchase, write a request for proposal (RFP)
or a request for information (RFI) and send it to the vendors on the short list.
After selecting a product, order, install, and test it.
2.
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Roles Involved in These Activities
BI infrastructure architect
The BI infrastructure architect is responsible for developing the capacity plans
for the hardware, middleware, DBMS, and network in order to ensure the
scalability needed by the BI decision-support environment. The BI
infrastructure architect and the database administrator have to work side by
side while evaluating the current environment, determining the appropriate
future platforms, and implementing the selected technologies.
Database administrator
The database administrator has to evaluate the current DBMS platform on the
current hardware. The database administrator also has to evaluate the tools
and the middleware as they relate to the DBMS. He or she has to determine the
future DBMS requirements and should participate in performing the technical
infrastructure gap analysis.
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Risks of Not Performing Step 2, Section A
In order to provide adequate performance in a growing BI decision-support
environment, it is mandatory to assess the hardware, middleware, DBMS, and tools
from time to time. If you do not perform this part of Step 2, technical performance
could degrade to such an extent that the BI decision-support environment becomes
unusable. It is also necessary to stay current with the existing technology.
Technology advances occur every few months. Not staying current and not taking
advantage of new and improved features can turn the BI decision-support
environment into an extinct dinosaur in a very short time.
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