Skip to main content
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 Adapter

The persistent storage adapter allows you to plug in your own storage solution that Statsig SDK uses to persist user assignments. The storage interface consists of just a load and save API for read/write operations.
Currently only supported in Go, Ruby, Legacy Node, Node Core, Kotlin, .Net, Python Core

​
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
      • Will only save when experiment / layer is active
    • load the previously saved evaluation of a persisted user on subsequent evaluations
  • CAVEAT Persisted Value will be deleted when:
    • When you provided call getExperiment with user_persisted_values=None
    • or When experiment is not active

​
Persistent Assignment Options (Limited SDK Support)

  • Enforce Targeting: boolean, default: false
    • Whether or not to enforce targeting rules before assigning persisted values
  • Kotlin
  • Node JS
val options = GetExperimentOptions(
  ...
  persistentAssignmentOptions = PersistentAssignmentOptions(
    enforceTargeting = true,
  )
)

​
Example usage

  • Ruby
  • Python (Python Core)
  • Node Core
  • Kotlin
  • Node JS
  • Go
  • .Net
Statsig.initialize(
  'secret-key',
  StatsigOptions.new(
    user_persistent_storage: DummyPersistentStorageAdapter.new
  )
)
persisted_user = StatsigUser.new({ 'userID' => 'test-123' })
exp = Statsig.get_experiment( # User gets saved to persisted storage
  persisted_user,
  'active_experiment',
  Statsig::GetExperimentOptions.new(
    user_persisted_values: Statsig.get_user_persisted_values(persisted_user, 'userID')
  )
)
puts exp.group_name # 'Control'
exp = Statsig.get_experiment( # User evaluates using values from persisted storage
  StatsigUser.new({'userID' => 'unknown'}),
  'active_experiment',
  Statsig::GetExperimentOptions.new(
    user_persisted_values: Statsig.get_user_persisted_values(persisted_user, 'userID')
  )
)
puts exp.group_name # 'Control'
⌘I