SQLAlchemy 是否支持多库，如何支持

After pondering on jd's answer I was able to achieve the same result for postgresql 9.2, sqlalchemy 0.8, and flask 0.9 framework:
from sqlalchemy import event
from sqlalchemy.pool import Pool
@event.listens_for(Pool, 'checkout')
def on_pool_checkout(dbapi_conn, connection_rec, connection_proxy):

tenant_id = session.get('tenant_id')
cursor = dbapi_conn.cursor()
if tenant_id is None:
    cursor.execute("SET search_path TO public, shared;")
else:
    cursor.execute("SET search_path TO t" + str(tenant_id) + ", shared;")
dbapi_conn.commit()
cursor.close()

http://stackoverflow.com/questions/13372001/multi-tenancy-with-sqlalchemy 这个不能够全部解答我的问题；但是整体上给了我一个思路。
很棒的解决方案；需要的同学可以自己读读。