Parses a database URL.

def parse_database_url(url):
    """Parses a database URL."""

    if url == 'sqlite://:memory:':
        # this is a special case, because if we pass this URL into
        # urlparse, urlparse will choke trying to interpret "memory"
        # as a port number
        return {
            'ENGINE': DATABASE_SCHEMES['sqlite'],
            'NAME': ':memory:'
        }
        # note: no other settings are required for sqlite

    # otherwise parse the url as normal
    config = {}

    url = urlparse.urlparse(url)

    # Remove query strings.
    path = url.path[1:]
    path = path.split('?', 2)[0]

    # if we are using sqlite and we have no path, then assume we
    # want an in-memory database (this is the behaviour of sqlalchemy)
    if url.scheme == 'sqlite' and path == '':
        path = ':memory:'

    # Update with environment configuration.
    config.update({
        'NAME': path or '',
        'USER': url.username or '',
        'PASSWORD': url.password or '',
        'HOST': url.hostname or '',
        'PORT': url.port or '',
    })

    if url.scheme in DATABASE_SCHEMES:
        config['ENGINE'] = DATABASE_SCHEMES[url.scheme]

    return config