TASM reclassified queries

Viewpoint
Enthusiast

TASM reclassified queries

Hi,

I need an opinion on a method in use for reclassification of queries (Viewpoint 15.11 and Database 15.0):

we have an active ruleset with 15 workloads definitions and two exceptions especially dedicated to reclassify a query :

from a Workload (WKL1) to another workload (WKL2) with Exception1

from a Workload (WKL2) to another workload (WKL3) with Exception2

.(all workloads WKL1,2,3 in Timeshare level)

Query running in WKL1 is reclassified into WKL2 when estimation of CPU is over 12 seconds (Query criteria Estimated Total Processing Time).

A query running in WKL2  can be reclassified to WKL3 (Low priority) as soon as estimation of CPU is over 120 seconds (Query criteria Estimated Total Processing Time).

 

So a query Q1 could start first in WKL1 and next be classified into WKL2.

Another query Q2 could start first in WKL2 if not already classified (according to the evaluation order of workloads) if Estimated Processing Time is over 12 seconds.

Questions:

  • Is there any possibility that query Q1 could be reclassified into WKL2 and immediately be reclassified into WKL3 if a new evaluation of processing time in WKL2 is over 120 seconds ?
  • or there is no place for a new estimation for Q1 ?

In fact actual consumption of CPU (AMPCPUTime) is often under estimation, so we observe reclassified queries that should have kept their original workload.

  • Does that organization cause an overload for the system and TASM management ?

 

Thanks for recommendations,

Pierre


Accepted Solutions
Teradata Employee

Re: TASM reclassified queries

Normally one would define exceptions based on actual resource consumption, not estimates.

There is no new estimate when the query is assigned to a new workload; execution continues with the same query plan.

 

1 ACCEPTED SOLUTION
1 REPLY
Teradata Employee

Re: TASM reclassified queries

Normally one would define exceptions based on actual resource consumption, not estimates.

There is no new estimate when the query is assigned to a new workload; execution continues with the same query plan.