Hello Alex,
You may also consider creating a replica and performing the export operation from that replica. There are various strategies to reduce impact on users when migrating your database; you may find relevant information on the Web, for instance the "Time reduction battle while migrating databases from hosted PostgreSQL to Google Cloud SQL"
page.
It may be worthwhile noting here that Google Groups are reserved for general product discussions. We cannot provide you any advice on your system’s architecture, and related best solutions. For programming, database management, system architecture, you may publish detailed information in forums such as stackoverflow, where experienced programmers are happy to help.