Large amount of data best practices.

Hello Experts,

I have an scenario where i have to extract large volume of data from SAP system to a external database using SAP PI. The process has to extract about 400.000 rows from SAP and send it to this external database. I guess the best way to insert the data to the database is using JDBC adapter but i'm wondering what's the best adapter i can use to comunicate SAP R/3 and SAP PI? What's the best way to send a message of 400.000 rows to SAP PI? Files, idocs, proxies? Could you please tell me if there's any documentation on the topic?

Thank you in advance.