5 pts.
 Data Warehouse Query Performance
We have a data warehouse with summary and detail level data with Cognos as the reporting tool.  If we have data for 100 large customers loaded in the fact tables and are trying to use Cognos Query Studio.  Here is the scenario:  one user has access to data for 5 customers through the security layer and another user has access to data for 25 customers.  Assuming the volume of data and other factors are the same per customer, should the query performance be slower for the user exposed to data for 25 customers versus the user with 5 customers?  If both users are using a customer select prompt and choosing 4 months of detail data, will the user with exposure to more customers have a longer response time?    

Software/Hardware used:
Cognos Query Studio and SQL Server
ASKED: May 21, 2010  1:24 PM
UPDATED: May 21, 2010  2:07 PM

Answer Wiki:
Accessing more data will take more resources (time, I/O, sort, etc). But it will not take 5 times as long. Too many variables come into play to be able to calculate without running some benchmarks.
Last Wiki Answer Submitted:  May 21, 2010  2:07 pm  by  Meandyou   5,205 pts.
All Answer Wiki Contributors:  Meandyou   5,205 pts.
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