32-bit vs 64-bit Ain't Just for Playstation and Nintendo

Redditor Aybabtu123 on the IBM Cognos subreddit asks:

"I'm putting together a 10.2.2 sandbox environment and I'd like to enable dynamic query mode on it. Is it true that all datasources must be 64 bit for this?"

This is a great question and one that IBM frequently discusses in a way that is clear as mud, so here is the answer as succinctly as I can phrase it. Assuming a 64-bit installation of Cognos on a 64-bit server with a 64-bit OS...

• With the Report Server Execution mode in Cognos Configuration set to 32-bit, queries routed to this server will execute in either CQE or DQM depending on how the datasource and package have been defined.
• With the Report Server Execution mode in Cognos Configuration set to 64-bit, queries routed to this server will only execute in DQM. CQE queries will error out.

Where the magic happens.

Cognos is automatically set to 32-bit Report Server Execution upon installation, so as long as you don't change it your application servers will be able to execute both 32-bit (CQE) and 64-bit (DQM) queries - and by extension utilize both CQE and DQM datasources.

Tomorrow (or soon anyway) we'll discuss what situations would warrant switching to a 64-bit only application server and the steps you need to take to properly route traffic. I'll give you a big hint though, and it rhymes with crynamic dubes.