To many users, "transaction wraparound" sounds like a disease from space. Mentioning "transaction wraparound" usually earns the speaker points for technical merit. Let's take a look at it, and how to avoid it.
First: have you seen the following message?
WARNING: database "postgres" must be vacuumed within XXX transactions.
HINT: To avoid a database shutdown, execute a database-wide VACUUM in that database.
You might also need to commit or roll back old prepared transactions.
Or even worse, the following message:
ERROR: database is not accepting commands to avoid wraparound data loss in database "template0"
HINT: Stop the postmaster and use a standalone backend to vacuum that database.
You might also need to ...