title: What is the benefit of using psycopg2 with SQLAlchemy
body: <p>I understand that psycopg2 is more of a DB driver, and SQLAlchemy is an ORM.</p>
  
  <p>As the latest SQLAlchemy already supports postgreSQL dialect and connection pools, what are the benefits of using psycopg2 (postgresql+psycopg2) or its connection pool over SQLAlchemy's ?</p>