Question & Answer
Is ERO (Enhanced Reporting Optimization) still required for Cognos Controller reports?
The ERO/Optimise2 function (Enhanced Reporting Optimization/ ERO) is used for passing information from the Application Server to the Database server in the most efficient way.
Starting with Controller 10.2.1FP2 the way these parameters are passed has been considerably improved, also if ERO is not used and reports are run with better performance in cases when ERO is not used.
The changed behavior is only applicable to Microsoft SQL Server and DB2 as database engines. No changes have been done for Oracle.
No changes in the reports are needed to benefit from the improved way of passing parameters.
ERO still gives somewhat better performance with a large number of fgetvals functions in a report, but with smaller reports there is no need for ERO:
It is difficult to exactly state when ERO is needed or not, but a rule of thumb could be that for both Report Generator and Excel Link reports with less than around 5-10,000 fgetvals the use of ERO is not needed anymore.
15 June 2018