Kudos to the team; some great releases this summer! (10x insert performance, regex queries, and now date/time and better disk space--all in ~90 days!)

I had never looked in to how rdb used disk space and off the cuff attributed its high usage to something similar to Mongo and allocating blocks ahead of usage.

This was something that went in to the negative column for me when I evaluated using rdb vs Postgres for a JSON dump. 12k somewhat light (but still larger than 250b) records ate up over 70MB of disk space in just over a couple days and I've not looked back. Time to give it another spin!