Hi All, I've been looking for a way to change experiment variation values and weights using a single API call (also to add/remove additional variations). The only way I found is to call 2 APIs. First - update experiment while setting a list of variations with new weights and second - update feature with variation's values inside the rule (experiment). Executing 2 API calls is not atomic and may cause issues on client side who reads the data. I didn't find a way to update values of variations through update experiment API. Did I miss something? Or there another way of doing so?

@victorious-nightfall-21291 has opened an issue Close Issue button

Hi, I’ve got your support request in my queue and I’ll follow up as soon as I can

There is not a way to do this with a single API call. The approach you outlined - updating the experiment first, then the feature, should work fine though. Even if the 2nd update fails, the feature will not break. The feature will be assigned a default value of

null

for any new variation that is not set. And if a variation has been removed, but the feature flag hasn't been updated, it will just ignore that extra variation.

• @future-teacher-7046 Thank you for your response. I'm having trouble understanding the answer. Could you please provide more details or clarify your response? I not really understand if we need to stop the experiment before it updated and if there is a way to expose 1 api that do it with atomic request • how the update will impact on the distribution of user that get the feature flag and participant in the experiment

Changing weights and variations while a test is actively running will likely cause data quality issues and lead to unreliable A/B test results. We recommend only doing that while the test is still in a draft state. It sounds like you might be trying to do something like a multi-armed bandit where you dynamically adjust weights and variations throughout a test? If so, we don't really support this use case right now, but it's on our roadmap.