As mentioned in another thread, automagic failover the one still pending, and geospatial indexes/searches (now in the product).

It's wild how many options there are that tailor themselves to all kinds of data out there.

I'm not involved with RethinkDB but I lurk on their github issues and I'm pretty confident that automagic failover is dependent on them getting (their own implementation of) Raft integrated with everything. Looks like its getting close as a whole slew of issues were opened just the other day relating to Raft work.

Are unique indexes planned for any of the upcoming releases?

The primary index for the table is always unique.

We do not plan to implement secondary unique indexes. The philosophy behind RethinkDB is that if a feature cannot be efficiently scaled across multiple nodes we don't add it, and unfortunately unique secondary indexes are one such feature.

AFAIK most NoSQL databases don't implement it, and a few that do take two approaches -- forbid it on multiple shards, or just take a massive performance hit during sharding.

We chose to keep the feature out of the database. This way the application can be architected to account for it, so it remains fast as the database scales up.

This is good, for what it's worth. Having different feature sets for sharded vs unsharded is just utterly confusing, and something MongoDB got really wrong.