When a user drills down into the data in an OLAP cube, the user
is analyzing the data at a different level of summarization. The level of
detail of the data changes as the user drills down, examining the data at
different levels in the hierarchy.
As the user drills down, he or she moves
from summary information to data with a more narrow focus. The following are
examples of drilling down:
Drilling down into data to look at demographic information about
the population of the United States, then into the state of Washington, then
into the metropolitan area of Seattle, then into the city of Redmond, and
finally into the population at Microsoft.
Drilling down into sales figures for Xbox 360 consoles
for the 2011 calendar year, then the fourth quarter of the year, then the month
of December, then the week before Christmas, and finally Christmas Eve.
Drill Through
When users “drill through” data, they want to see all
the individual transactions that contributed to the OLAP cube’s aggregated
data. In other words, the user can retrieve the data at a lowest level of
detail for a given measure value.
For example, when you are given the sales data for a
particular month and product category, you can drill through that data to see a
list of each table row that is contained within that cell of data.
It is common to confuse the terms “drill down” and
“drill through” with each other. The main difference between them is that a
drill-down operates on a predefined hierarchy of data—
For example, USA, then into Washington, then into
Seattle—within the OLAP cube. A drill-through go directly to the lowest level
of detail of data and retrieves a set of rows from the data source that has
been aggregated into a single cell.
No comments:
Post a Comment