Why variation in exception count while accessing DB2 data

sandeep1dimri · New User Joined: 30 Oct 2006 Posts: 76

Why exception count is not increasing when my program accessing the DB2 tables and it increses when i uses downloaded version of table-i.e simple read from file.

Thanks in Advance

dick scherrer · Posted: Tue Apr 10, 2007 4:14 am

Hello,

First - the term you want is probably not "exception count" - i believe the term you want is EXecute Channel Program count.

To read from (or write to) a "flat" or vsam file, your program issues a read or write and the EXCPs increase.

When you read from a database table, you issue a request to DB2 and the read is issued by DB2. The EXCPs for DB2 will increase as your program runs.

Please let us know if you'd like additional info

sandeep1dimri · New User Joined: 30 Oct 2006 Posts: 76

Thanks scherrer

please explain differenec between EXecute Channel Program count and exception count wrt DB2 access.

One more query:
If we change our approach from accessing data from DB2 to accessing data from file then how to conclude that we are saving CPU?

Thanks
Sandeep

sandeep1dimri · New User Joined: 30 Oct 2006 Posts: 76

Ple can anyone put some views on it

dick scherrer · Posted: Fri Apr 20, 2007 7:19 pm

Hello,

The difference is resources directly used by your task and only your task versus resources that are used in common. For example - if your job uses a PS file all of the i/o is directly related to your job. If your job uses database some of the i/o is related to your job, but not all of it. In a database, tables may be used by several jobs concurrently, so the resources are not directly related to one job.

My suggestion is that you re-focus. Typically, cpu time is not the only thing considered. If you want to determine if one alternative is more cost-effective than another, you need to compare all of the (machine) resources used. To find resources used, you might talk with your performance monitoring people - almost everywhere keeps stats on how many resources are used by various processes.

Usually, switching between a database and some external file structure is not a choice. Also, usually, the choice is not made on the basis of performance.