[siddontang]

Interesting feature, I think we can learn from this in our product.

IMO, it is still not safe even we know there are no queries running for this table. You may still meet a scenario that when you type `drop table`, another guy begins to run the query at the same time.

As the maintainer of another database, We have been trying our best to improve this scenario too.

Early on, we have provided a feature called `recover table` to recover table immediately after you wrongly drop the table. But this still can't avoid affecting current running queries on this table.

We call this problem `DDL affects DML`, and now we try to introduce a Table meta lock to guarantee that no any query is running when the DDL executed. We hope we can release this feature in the end of this year.