[Sqlalchemy-tickets] Issue #4043: sqlite does not support deferred keyword on (unique) constraint (zzzeek/sqlalchemy)

[Martin B. <iss...@bi...>]

New issue 4043: sqlite does not support deferred keyword on (unique) constraint
https://bitbucket.org/zzzeek/sqlalchemy/issues/4043/sqlite-does-not-support-deferred-keyword

Martin Babka:

When using sqlite and setting 


```
#!python

class Model(Base):
    __tablename__ = 'users'

    id = Column(Integer, primary_key=True)
    name = Column(String)
    order = Column(Integer)

    __table_args__ = (UniqueConstraint('order', name='single_occurrence_of_order', deferrable=True),)

```

then creating the tables throws sqlite's syntax error:


```
#!text

sqlalchemy.exc.OperationalError: (sqlite3.OperationalError) near "DEFERRABLE": syntax error [SQL: '\nCREATE TABLE users (\n\tid INTEGER NOT NULL, \n\tname VARCHAR, \n\t"order" INTEGER, \n\tPRIMARY KEY (id), \n\tCONSTRAINT single_occurrence_of_order UNIQUE ("order") DEFERRABLE\n)\n\n']
```

[Issue 2841](https://bitbucket.org/zzzeek/sqlalchemy/issues/2841) addresses the problem for MySQL, a similar solution may be done in case of sqlite. 

I could resolve the problem as in [this commit](https://bitbucket.org/zzzeek/sqlalchemy/commits/cf1ac72bca8b0bc28e09cdb4cdf052bcf82e5076).