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How to avoid duplicates when using dataset? Messages in this topic - RSS

Unregistered User
Unregistered User
Posts: 393


4/14/2021
Unregistered User
Unregistered User
Posts: 393
I was getting in touch as our team may have found a potential bug. Can SS confirm whether they are seeing the same issue please? Below are the details:

Details:
  • Vusers: 30
  • Dataset entries: 210
  • Limit Dataset: Yes and “0”, i.e. all of the data was available to each VU.
  • In our recent performance tests we have set “How to count iterations” to “Per VU”. This has shown the VUs, picking unique data from the dataset with each iteration.
  • However, we recently changed the setting to the below. In theory, we assumed by choosing this option we wouldn’t need to calculate the number of “Max Iterations” per VU. Because we would simply enter the total number of iterations the all vusers should complete.
  • What we discovered when selecting this option is the first 15 VUs would select unique rows data from the dataset, however, after that point the next VU seemed to pick the first row from the dataset. This caused duplicate orders to be created with the same subject details.
  • By the end of test this setting achieved the goal of completed the Max Iterations set. However, during the process it ended up creating duplicate orders.




Can SS confirm whether our assumption on how this option works is correct?
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George @StresStimulus
George @StresStimulus
Administrator
Posts: 409


4/22/2021
George @StresStimulus
George @StresStimulus
Administrator
Posts: 409
This behavior is by design and here is why and how to avoid it:


I am assuming you are using VU-Iteration-Bound binding for your dataset. The formula that calculates which record will be used (https://support.stresstimulus.com/display/doc53/Databinding ) is
Record Row number = (Iteration #) * (Max VUs) + (VU #)


When you set the How to count iterations property to Total, you do not guarantee that every iteration will get an equal number of iterations. If VU1 executes ten iterations, then on the 10th iteration, it will use the 301-st record, but since you only have 210 records, the scripts will re-use the top records.


I suggest setting the VU-to-row mapping to On-Demand described https://support.stresstimulus.com/display/doc53/Default+databinding and try rerunning the test.`



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