Python - Send csv to database

Question

I’m writing a script that joins all files of the same format into a folder and creates a single CSV and I want to send that CSV to the database. As new files enter this folder, CSV will always create new lines.

However, I am using this command to send the files to the database..

conn = psycopg2.connect(host="",database="",user="",password="")

cur = conn.cursor()
with open('extratos.csv', 'r') as f:

        cur.copy_from(f, 'extratos', sep=',')

        conn.commit()

But every time script wheel it reads the CSV file from the beginning and accuses that the first line is already in the database. How do I send only the new inserted lines?