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Cohort Limitations

  • 9 May 2023
  • 5 replies
  • 181 views

Hi All and Amplitude Team!

I’ve been having an issue where the cohort that I wanted to create keeps not getting computed. The cohort do have a lot of line condition but I was wondering if there are any limitations or ways that I can do to help compute the cohort.

Below is the screenshot of the data that has not computed. It usually happens when I want to substract a certain cohort.
 



 

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Best answer by Thao Nguyen 16 May 2023, 09:46

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5 replies

Userlevel 5
Badge +8

@Vania Alya welcome to the community! I’ve sent this along to our support team so they can dig into this cohort further.

Userlevel 3
Badge +5

Hi @Vania Alya, sorry to hear that you are having issues with cohort creation. I had a looked at the source cohorts and they do include a number of conditions, which can impact computation time. I tried building the same cohort as shown in your screenshot and it took about one minute to finish computing. 

Do you mind re-creating the cohort and monitoring if it is complete? If not, I will escalate it to our Engineering team to investigate if needed. 

Thank you!

Best regards,

Thao

Hi @Thao Nguyen and @Esther Trapadoux , thank you assessing this issue. I tried recreating the cohort and it generated the output but I couldn’t save this cohort. After a while, an error for saving was seen.

This error for not able to save the update to a cohort has happened to me a couple of times too.

Another thing is that, while waiting for saving I found the new cohort [Fix] Revenue that I wanted to save in my Cohort List. However, it couldn’t compute and eventually showed 0 user.


If I could get an insight and help regarding this, Thank you!

Userlevel 3
Badge +5

Hi @Vania Alya thank you for getting back to us! This looks like a bug. I’ve escalated it to our Engineering team to investigate why the saved cohort size is 0. I will let you know as soon as I hear back.

Apologies for the inconvenience! 

Best regards, 

Thao

Userlevel 3
Badge +5

Hi @Vania Alya thank you for your patience!

After taking a closer look, we found that the cohort [New] Referral (Retention + Refer Someone) is built based on the cohort [New] Revenue (Transaction > 1, diff verical), specifically it includes users from [New] Revenue (Transaction > 1, diff verical).

Therefore, you can’t add the second clause “not part of cohort [New] Referral (Retention + Refer Someone)” because these two cohorts conflict, resulting in the save failed and returned 0 users. If you chose a different cohort for the second clause that doesn’t have clashing conditions, it will still work.

I understand that the preview says more than 75,000 users who match the condition. Our Engineer advised that the preview runs a temporary computation of the cohort size when you make a change. However, it doesn’t run a thorough check for the definition until you hit Save. In this case, it errored out during the saving process. 

Hope this helps! Let me know if you have any questions.

Best regards,

Thao

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