Index access and privacy#

ANNImputer supports different index-access/ownership modes. The distinction matters because a nearest-neighbor index is derived from training data and may still reveal information about it.

Private ownership

Keep the index encapsulated by the estimator when callers should not receive direct index access.

External/public ownership

Useful when an application intentionally manages or shares the index, but the caller becomes responsible for storage, lifetime, permissions and exposure.

On-disk indexes are artifacts and should inherit the sensitivity of the data used to build them. Memory mapping reduces duplicate RAM use; it does not make an index anonymous or safe to publish.