Why asynchronous?  Well, we have two other operations working with the skip list in a manner that requires exclusivity:

1. Flushes to disk: Routine, shutdown of system, etc.
2. Query planner executing a batch that needs to scan over the in-memory database.

``appendToMemoryQueue`` should be liberally large to prevent said backlogging.  We can add telemetry to observe its size over time.