Currently the PQS module provides two different methods for the lookup on the router and shard. In order to make things simpler one could introduce a generic QuerySettingsService interface and provide two different implementations depending on the instance (via pimpl).

The proposal would be to:

• Provide such implementation, but do not adjust the callers with the new API, but instead delegate the implementation to the methods provided by the service instance (would require only query-settings team code review)
• Adjust the callers with the new interface (the implementation is same, just interface change, therefore trivial review)