Cognos Tips and Solutions

In some cases Cognos Performances can degenerate and Reports elaboration becomes very slow. Example of critical cases: 

• Cognos Query using 2 separated DataSources

• Using Label instead of ID in the filters, in a model with Fact Table (with ID) in join with configuration table with ID and Labels.

• Join between 2 or more fact tables

• Report Studio field showing the distinct values of a Fact Table field, retrieved form very large DB table (example: distinct of Date field to show the distinct days of data involved in query)

The impact of not efficient design could be catastrophic:

1. Very Slow Report (many minutes or hours) also when showing only few records.

2. Overload of Cognos Server System Resources (CPU, Disk I/O, Memory).

3. Cognos crash or Hungup (Reports waiting for execution due to all resources busy)

There are some generic rules that could be implement with very simply modification,  allowing in some cases incredible improvements (like decreasing Report Time from more than  10 minutes to few seconds).

In other cases there are only specific solution and performance issue investigation could be complex, requiring very good know-how of both Cognos and DB tecnologies.