Skip to main content

Persistent Assignment

Persistent assignment allows you to ensure that a user's variant stays consistent while an experiment is running, regardless of changes to allocation or targeting.

Persistent Storage​

The persistent storage adapter allows you to plug in your own storage solution that Statsig SDK uses to persist user assignments. The user persistent storage interface consists of just a load/loadAsync, save, delete API for read/write operations.

info

Currently only supported in Javascript, iOS and Android

Persistent Storage Logic​

  • Providing a storage adapter on Statsig initialization will give the SDK access to read & write on your custom storage
  • Providing user persisted values to get_experiment will inform the SDK to
    • save the evaluation of the current user on first evaluation
    • load the previously saved evaluation of a persisted user on subsequent evaluations
    • delete the previously saved evaluation of a persisted user if the experiment is no longer active
  • Not providing user persisted values to get_experiment will delete a previously saved evaluation

Example usage​

await statsig.initialize('client-key', {userPersistentStorage: new CustomStorageAdapter()});

const user = { userID: "123" };
const userPersistedValues = await statsig.loadUserPersistedValuesAsync(user, 'userID');

let experiment = statsig.getExperiment({userID: "123"}, 'the_allocated_experiment', { userPersistedValues: userPersistedValues });
console.log(experiment.getGroupName()) // 'Control'

experiment = statsig.getExperiment({userID: "unknown"}, 'the_allocated_experiment', { userPersistedValues: userPersistedValues });
console.log(experiment.getGroupName()) // 'Control'