I would very much like to see a rename-constraint option.
I have read your comment on
#246 (relational databases don't generally have RENAME CONSTRAINT functions) and I'm not sure that that is the case:
Oracle and Postgre support it
Mssql and Sybase have a stored procedure sp_rename for renaming constraints.
* Mysql, Firebird and Sqlite don't currently support it
Meaning that more than half of the dialects supported by sqlalchemy support a rename constraint method while the others can do a drop-create in order to support it.
Supporting the rename constraint should improve performance and readability