what is the recommended way of setting up an sqlalchemy connection for view callables?

I am using the sqlalchemy expression language for its notation and connection pooling to create dao objects for communicating with the persistence layer. I wanted to get some opinions on how I should approach setting up the metadata and engine so that they are available to the applications view callables. According to sqlalchemy's documentation http://docs.sqlalchemy.org/en/rel_0_7/core/connections.html, they are typically bound and declared global, however I've neither this or the singleton approach are good ideas. Any thoughts would be appreciated...

This is what my __init__.py file looks like inside my project's directory:

from pyramid.config import Configurator
from sqlalchemy import engine_from_config, MetaData, create_engine
from pyramid_beaker import session_factory_from_settings

db_url = 'postgresql://user:password@localhost/dbname'
engine = create_engine(db_url)
meta = MetaData()

def main(global_config, **settings):
    meta.bind = engine
    .
    .
    .
    [other configuration settings]