Faster way to perform bulk insert, while avoiding duplicates, with SQLAlchemy
<p>I'm using the following method to perform a bulk insert, and to optionally avoid inserting duplicates, with SQLAlchemy:</p>

<pre><code>def bulk_insert_users(self, users, allow_duplicates = False):
    if not allow_duplicates:
        users_new = []

        for user in users:
            if not self.SQL_IO.db.query(User_DB.id).filter_by(user_id = user.user_id).scalar():
                users_new.append(user)

        users = users_new

    self.SQL_IO.db.bulk_save_objects(users)
    self.SQL_IO.db.commit()
</code></pre>

<p>Can the above functionality be implemented such that the function is faster?</p>

<p>You can load all user ids first, put them into a set and then use <code>user.user_id in existing_user_ids</code> to determine whether to add a new user or not instead of sending a SELECT query every time. Even with ten thousands of users this will be quite fast, especially compared to contacting the database for each user.</p>

python sqlalchemy