This document provides general recommendations for the amount of memory that should be allocated for the Java Virtual Machine (JVM) heap associated with dynamic query mode (DQM).
Resolving the problem
Although the dynamic query mode (DQM) is supported in 32 bit installations of IBM Cognos BI servers, 64 bit servers are recommended for DQM.
The initial size and size limit of the JVM heap for DQM can be set in Cognos Administration via the Settings tab of the QueryService (steps). By default each of these are set to 1 GB.
In production environments where Cognos Dynamic Cubes are not employed, it is recommended to set the initial heap size to 4 GB and the limit to 8 GB (a 64 bit server is required for memory settings above 2GB) and then monitor system resource usage during peak hours and adjust the settings accordingly.
For a server that is operating one or more Cognos Dynamic Cubes, the size limit of the query service should be set in accordance to the Dynamic Cubes hardware sizing recommendations.