Difference between MAXAMPCPUTIME from DBQLSTEPTBL vs DBQLOGTBL

Database
Highlighted
Enthusiast

Difference between MAXAMPCPUTIME from DBQLSTEPTBL vs DBQLOGTBL

Hi, 

 

We are seeing different values for maxampcputime in the 2 tables for the same query id, can someone explain if there is a difference in how this column is interpreted in DBQLSTEPTBL vs DBQLOGTBL?  

3 REPLIES
Teradata Employee

Re: Difference between MAXAMPCPUTIME from DBQLSTEPTBL vs DBQLOGTBL

One represents individual steps and the other request-level totals.

And you can't simply sum step max values to find the total max, because the max for one step may occur on a different AMP (MaxCPUAmpNumber) than another step.

Enthusiast

Re: Difference between MAXAMPCPUTIME from DBQLSTEPTBL vs DBQLOGTBL

Thanks Fred, in this case, isnt it always more accurate to calculate the impact cpu from the maxampcputime*numofactiveamps from the step table rather than the maxampcputime*numofactiveamps?

Teradata Employee

Re: Difference between MAXAMPCPUTIME from DBQLSTEPTBL vs DBQLOGTBL

One could certainly calculate an "impact CPU" measure at the step level. But that's a diferent measure, I wouldn't necessarily call it more accurate.