The streaming ingestion job should be able to transition to reading from a new generation when a new one advertises itself.

A stream may be composed of several generations. A generation is defined by a start-time which indicates the time at which changes started being emitted to that particular generation. A stream might periodically produce a new generation (when a new generation is created, it will eventually stop writing to the old one).

Upon notification of a new generation, the ingestion job should plan a new flow for the new generation and pickup ingesting the stream.