Morgan from the TiDB team here. We are working on at rest encryption now - stay tuned.

w.r.t. nested transactions, this is not something that MySQL currently offers (TiDB is MySQL 5.7 compatible). Sometimes this is emulatable via savepoints, which is a feature we plan to add in the future.

How good or bad is the SqlAlchemy support?

It should work fine, with one item to note:

I believe SqlAlchemy defaults to READ-COMMITTED, whereas TiDB defaults to (and recommends) MySQL's default of REPEATABLE-READ.

Any chance you guys run it against the SQLalchemy test suite?

I’ll check it out today. Thanks.