Investigate direct asynchronous partition insertion

The system current tries to insert all processed rows into the parent table. Investigate the possibility of determining available partitions and inserting directly to those asynchronously in order to add another level of concurrency to save time.

No file, test, or entry point is named. Start by locating the code that inserts processed rows into the parent table, then inspect how partitions and asynchronous work are currently handled; done means a validated design or implementation that can insert into available partitions concurrently and demonstrates the expected time savings.

Written by the indexing model from the issue text.