The DBA Corner
Craig S. Mullins
DBA Change Management
The only constant in
today's complex business environment is change. Both businesses and
individuals can find it difficult to cope with change. For individuals
change usually involves taking on additional work – and who wants to do
that if they can avoid it? For businesses, change can be as simple as
adapting to a new employee or as complex as merging with another
company. At any rate, change requires our attention in order to ensure
that business continues to be conducted properly.
There are many different aspects of managing change,
particularly with respect to Information Technology. IT professionals
are constantly adding, removing, and adjusting various aspects of the
infrastructure: servers, networks, applications, middleware, and so on.
With regard to databases, DBAs always need to be prepared to modify
database structures to accommodate business changes.
Indeed, many factors conspire to force us into changing
our database structures, including
Changes to application programs that require additional or
modified data elements
Performance modifications and tweaks to make database
applications run faster
Regulatory changes that mandate storing new types of data
or the same data for longer periods of time
Changes to business practices that require new data or
changes to existing data
Technological changes that enable databases to store new
types of data and more data than ever before
And change will not slow down any time soon, so we need
to prepare solutions that enable us to better manage these inevitable
changes. To successfully implement an effective database change
management policy you will need to consider many factors including
proactive change, intelligent automation, planning and impact analysis,
standardization, and availability.
Proactive change, which can eliminate future problems,
can be one of the most valuable types of change. The earlier in the
development cycle that required changes can be identified and
implemented, the lower the overall cost of the change will be.
Automating change management processes is important,
too. With limited resources and growing workloads, automation can help
to reduce the amount of time, effort and human error involved in
effecting database change. But simple automation is no longer
sufficient. The impact of each change needs to be examined before
implementation. A simple change in one area may cause a complex change
in another. Intelligent automation of change management processes
incorporating in-depth analysis can improve the quality of your database
And speaking of analysis, an effective DBA will ensure
that each change undergoes exhaustive up-front planning and analysis.
Comprehensive impact and risk analysis is needed in order to gain a
macro view of the change. The only way to know which change tactics are
optimal is to conduct an in-depth impact analyses, and then choose the
most effective, efficient, and worthwhile strategies.
Standardization is also important. With attrition,
promotions and changing job roles a standardized process is needed to
maintain productivity. An organized and thoroughly documented approach
to completing a task reduces the learning curve, as well as training
Keep in mind, too that many database changes require
down time to implement. Database structures may need to be taken offline
in order to effect change. But high availability is required of most
applications these days, especially web-based applications. Reducing the
downtime required to make a database change increases application
availability. Indeed, all of the tactics discussed up to this point can
help to reduce downtime when databases are being changed.
Keeping in mind everything discussed to this point, we
turn our attention to the DBA. Even though the DBA is the custodian of
database changes, he usually is not the one to request a change; that is
typically done by the application owner or business user. There are
times, too, when the DBA will request changes, for example, to address
performance problems or to utilize new features or technologies.
Regardless of who requests the change, the DBA is charged with carrying
it out and ensuring that all changes are performed successfully and with
no impact to data integrity.
Without a robust, time-tested database change procedure,
the DBA will encounter difficulties. Why? Well, most DBMS products do
not support fast and efficient database structure changes. Each DBMS
provides differing levels of database change functionality. But none
easily supports every type of change that might be required. One quick
example: most DBMSs today do not enable a column to be added easily to
the middle of an existing row. To accomplish such a task, the DBA must
drop the table and recreate it with the new column added. But when the
table is dropped the data is deleted, too. So the DBA must first unload
the data. But what about the indexes on the table? They would have been
dropped when the table was dropped, so unless the DBA knows this and
recreates the indexes too, performance will suffer. The same is true for
constraints, authorizations, and so on – when the table was dropped all
structures related to the table were also dropped. And this is but one
example of a simple change that becomes difficult to implement and
Database change quickly can monopolize a DBA’s time.
Preparing for change and implementing the proper tools, techniques, and
procedures for database change management is one of the most important
jobs undertaken by DBAs today.
© 2006 Mullins Consulting, Inc. All rights reserved.