document how to specify backend-specific DDL sequences

[Former user]

Postgre doesn't support deferrable unique constraints, though when adding a multicolumn UniqueConstraint at table level with deferrable=True, SQLA still emits the DEFERRABLE keyword in the DDL, I would have expected SQLA to suppress this?

Quoting from the Postgre docs (8.3 and 8.4): "This controls whether the constraint can be deferred. ... Only foreign key constraints currently accept this clause."

http://www.postgresql.org/docs/8.3/interactive/sql-createtable.html http://www.postgresql.org/docs/8.4/interactive/sql-createtable.html

[Mike Bayer]

the only question is, raise or ignore ? if the answer is "raise", then nothing should be done here - the DB already raises. Silently ignoring something as major as "deferrable" seems like a mistake.

0.6 supports the attachment of DDL events to specific backends so that would be the appropriate user technique.

[Mike Bayer]

this is in http://www.sqlalchemy.org/docs/06/metadata.html#controlling-ddl-sequences

[Mike Bayer]

Removing milestone: 0.6.0 (automated comment)