The Importance of Meta Data
Meta data describes an organization in terms of its business activities and the
business objects on which the business activities are performed. Consider, for
example, a sale of a product to a customer by an employee. The sale is a business
activity and the product, customer, and employee are the business objects on which
the sale activity is performed. Business activities and business objects, whether
manual or automated, behave according to a set of relationships and rules, which
are defined by the business. These activities and objects, and the relationships and
rules that govern them, provide the context in which the business people use the
business data every day.
Meta data is so important for the BI decision-support environment because it helps
metamorphose business data into information. The difference between data and
information is that information is raw data within a business context. Meta data
provides that business context; that is, meta data ensures the correct interpretation
(based on activities, objects, relationships, and rules) of what the business data
actually means.
For example, what is profit? Is it the amount of money remaining after a product has
been sold and everybody who was involved in that product has been paid? Or is it a
more complicated calculation, such as "total annual revenue minus sum of average
base cost per product minus actual staff overhead minus accumulated annual
production bonuses minus wholesale discounts minus coupons divided by twelve?"
Does every business person have the same understanding of profit? Is there one and
only one calculation for profit? If there are different interpretations of profit, are all
interpretations legitimate? If there are multiple legitimate versions for profit
calculations, then multiple data elements must be created, each with its own unique
name, definition, content, rules, relationships, and so on. All of this contextual
information about profit is meta data.
Since meta data provides the business context in which business data is used, meta
data can be viewed as a semantic (interpretive) layer of the BI decision-support
environment. This semantic layer helps the business people navigate through the BI
target databases, where the business data resides. It also helps the technicians
manage the BI target databases as well as the BI applications.
Some important characteristics of meta data and meta data repositories are listed
below.
A meta data repository is populated with meta data from many different tools,
such as CASE tools, ETL tools, OLAP tools, and data mining tools.
Meta data documents the transformation and cleansing of source data and
provides an audit trail of the periodic data loads.
Meta data helps track BI security requirements, data quality measures, and
growth metrics (for data volume, hardware, and so on).
Meta data provides an inventory of all the source data that populates the BI
applications.