TotalCpuTime and response time

Database

TotalCpuTime and response time

We calculate response time as: (FirstRespTime - StartTime) in DBQLogTbl. This value is sometimes big with 0 in TotalCPUTime.
How can this be possible?

Doesn't the difference between FirstRespTime and StartTime signify that the query has brought some impact on the Teradata system and some CPU consumption must have been made?
3 REPLIES
Teradata Employee

Re: TotalCpuTime and response time

No, because the task/query may require 0.001 micro seconds of a CPU time but may have to wait for 1 second before getting that CPU time, there surely is a difference between the two!

Regards,

Adeel

Re: TotalCpuTime and response time

Your explanation about Response time makes sense.
But I can see such entries (with 0 CPU time) with TotalIOCount > 0. Does this look right?
Teradata Employee

Re: TotalCpuTime and response time

DBMS may be using caching, it may not be doing an actual disk I/O, and it may also be due to rounding-off errors.

I guess the best answer of CPU time, I/O time etc can only be given by DBMS itself.

Regards,

Adeel