Explorations on a theme: "What is a transaction? "

6.  Consequences of Data Duplication

(Hint: click the other triangles to navigate to the other slides.)

Whenever data is stored in more than one place, these consequences always result:

• The redundant data stores attract updates from different classes of users

• Those updates happen in different sequence, and in different groupings or levels of aggregation

• Neither data store is ever correct.

• Time is wasted confirming one against the other

• Costs arise due to business errors based on wrong information (overdrafts, credit/collection errors, etc.)

• Systems are developed to address the problems, by automating the checking and comparison of the two lists, or to post all changes to both lists, or force the two organizations to work the same way, etc.

• Those secondary systems introduce rigidity and problems throughout the software environment.

These costs and consequences are geometric in nature, and are the root of our current employment of tens of millions of clerical workers, each operating completely isolated accounting systems.