How split by percentage works
CloudBees Feature Management utilizes a distributed algorithm. This algorithm is similar to tossing a coin on the device. But once a coin is tossed the result is consistent for a feature flag.
| Split by percentage only works for string and number type flags once you have defined feature-flags:feature-flag-setting.adoc#_feature_flag_variations. |
How the algorithm works
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The client side SDK generates a UUID (called
rox.distinct_id) and serializes it on the device. -
Every feature flag has its own seed to make sure there isn’t a statistical bias between 2 feature flags.
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The SDK takes the seed and
distinct_idand runs a hash function that is mapped to a double number from 0-1.
If you select a 50% split, for example, then we are checking if the hash result is smaller the 0.5.
Implication of the algorithm
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The result is consistent, every time a user opens the app they will get the same result (unless you changed percentage).
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If you increase percentage, all your existing users that already received true value will keep getting it.
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If you decrease percentage, some of your users will stop receiving a true value even if they have received one before.
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A single user’s place in the bucket is different in every feature flag (so your users will not always get a new feature).
| Override distinct_id with user id You can choose to override the
See also Flag context. |