What is DQM (Dynamic Query mode)

[dech008]

Hi,

I have big trouble understanding the concept of DQM.
Can anybody explain me how DQM actually works.

What i know : Its enhanced java based query mode we have to have connection to JDBC and content store. It is intelligent in-memory caching and can plan the queries dynamically.

Although i do not understand the working DQM.
Please help!!!!!

Thanks & Regards,
Debashish

[MFGF]

Hi,

I have big trouble understanding the concept of DQM.
Can anybody explain me how DQM actually works.

What i know : Its enhanced java based query mode we have to have connection to JDBC and content store. It is intelligent in-memory caching and can plan the queries dynamically.

Although i do not understand the working DQM.
Please help!!!!!

Thanks & Regards,
Debashish

Hi,

DQM is a query engine embedded within your Cognos instance. Unlike CQM, it runs within the Cognos JVM and is 64-bit. It uses JDBC to connect to relational sources, and provides much better query planning and caching than CQM.

A good resource to find out about DQM is the Dynamic Query Cookbook:

http://www.ibm.com/developerworks/data/library/cognos/infrastructure/cognos_specific/page529.html

Cheers!

MF.

[the6campbells]

The documentation which ships with the product and IBM redbooks explain what it is

http://www.redbooks.ibm.com/abstracts/sg248121.html

http://www-01.ibm.com/support/docview.wss?uid=swg27037021#cbiv10r2m1en

[dech008]

Thanks for reply guys.

Hi MF,

What i understood is than when we use CQM, we use database query engine and database execution plan. where as with DQM we use embedded query engine to our cognos instance which resides in cognos JVM and as bcoz its kind of local planning of limited data its fast.

Let me know if i am incorrect.


Thanks & Regards,
Debashish

[NYD3030]

This is a pretty broad topic actually and how DQM queries execute will depend in part on how you've modeled the FM package and whether or not you're using a dynamic cube.

From a high level though you are correct in how CQE vs DQM queries execute.  A DQM query has access to an in-memory cache specific to the application server on which the query is executing, and as part of the local query  plan will pull data from that cache. This can greatly enhance query performance in cases where you've built your model correctly.

The hierarchy of usefulness for DQM mode is regular package>DMR package>dynamic cube.  I provide some high level guidance on how to think about DQM on my blog that you may be interested in, http://ibmblueview.com/category/cognos/administration/. If you have specific questions I will try to answer them here and in a follow up blog post.

Cheers!