30-06-2012, 02:40 PM
Data Cube and OLAP Server
Data Cube and OLAP Server.ppt (Size: 199.5 KB / Downloads: 67)
What is Data Analysis?
User issues a query, receives a response and formulates the next query based on the response
This process repeats until the user gets the required result
Fundamentally an iterative process
Limitations of GROUP BY
Users want CrossTabs
GROUP BY is limited to 0-D and 1-D aggregates
Users want sub-totals and totals
drill-down & roll-up reports
OLAP System
On-Line Analytical Processing System
Interactive system
Permits analysts to view summaries of multidimensional data
On-Line indicates
No long waits to see result of a query
response times within a few seconds for new summaries
View data at different levels of granularity
Rollup and Drill down
Allow analysts to view data at any desired level of granularity
Rollup
Operation of moving from finer-granularity of data to a coarser granularity
Drill Down
Operation of moving from coarser-granularity of data to a finer granularity
Cannot be generated from coarse-granularity data
Has to be computed from original data