Incremental updates of data stored by reference

[tpendragon]

Hydrator should support incremental updates of dependent rows for Ephemera Folders

Acceptance Criteria

• If a Genre is updated, every folder that uses that genre should rehydrate to include that genre's new information.

Technical Tips

To process a term, do a giant loop and process everything that uses that term.
To optimize this, you could only loop through the folders that are older than the term.
TODO: Add source_cache_order_record_id to keep track of where the cache_order came from.

When storing the hydrator cache entry, the timestamp in the cache_order should be the timestamp of the row that caused that creation - in this case, the genre update.

First Step

Talk about how to do this.