I discussed in an earlier post the misconception that 32-bit Cognos application servers cannot execute 64-bit Cognos queries when in fact they can. This means that for most Cognos customers leaving the report service execution mode set to 32-bit is a smart move; existing 32-bit CQE content will work alongside 64-bit DQM content and you do not have to set up advanced routing rules to prevent 32-bit queries from hitting a 64-bit server. There are three cases in which I recommend deviating from this path:
- You have extremely visual reports: When a query comes in that requires DQM your 32-bit Report Service will hand it off to the 64-bit Query Service to build and execute the query plan. The Query Service will pass the result set back to the Report Service to generate the report and everyone wins. If, however, your reports are extremely visually complicated the 32-bit Report Service can still serve as a bottleneck as it is restricted by the old-school RAM limitations of 32-bit processes. Routing this report to a 64-bit DQM server will resolve this problem.
- You are making the leap to Dynamic Cubes: This one is more of a preference than a hard-and-fast rule, but if you intend to realize the ridiculous performance gains that come with Dynamic Cubes I highly suggest you quarantine them to a 64-bit only server and route all Dynamic Cube traffic to that server. This will simplify troubleshooting and performance tuning for your cubes and secure your CQE queries against disruption. It also gives you a 64-bit landing place as you migrate legacy queries to DQM.
- You are a new Cognos customer: If you are reading this having just inked your five year enterprise licensing agreement with IBM, you need to ensure that you are only building and developing in DQM. I cannot emphasize enough the importance of this point. I have it on very good authority that CQE will receive only bug-fixes going forward and that future versions of Cognos will execute CQE queries but all new development will be DQM only. Do not devote a single second to learning about or developing CQE content!
So there you have it! If you are an existing Cognos customer you should feel fine leaving the report service execution mode on 32-bit and riding those CQE queries as long as you can. I recommend standing up a 64-bit DQM server only if you run into performance issues caused by the 32-bit report service for the time being.
Everyone needs to be planning a migration to 64-bit only, however. Dynamic Cubes are a great reason to start but the fact is that 64 bit Cognos is the future, and the future may be much closer than you think…
Yes that ending was intentionally cryptic. Not sure how much I can talk about yet… 😉