Re: Prevent internal error at concurrent CREATE OR REPLACE FUNCTION

I found that multiple sessions concurrently execute CREATE OR REPLACE FUNCTION
for a same function, the error "tuple concurrently updated" is raised. This is
an internal error output by elog, also the message is not user-friendly.

I also found the same error is raised when concurrent ALTER FUNCTION commands are
executed. I've added a patch to fix this in the similar way.

FWIW, the same error is raised also with concurrent GRANT/REVOKE on a
database:
https://www.postgresql.org/message-id/18dcfb7f-5deb-4487-ae22-a2c16839519a%40gmail.com

Maybe you would also find relevant this thread:
https://www.postgresql.org/message-id/flat/ZiYjn0eVc7pxVY45%40ip-10-97-1-34.eu-west-3.compute.internal

Best regards,
Alexander Lakhin
Neon (https://neon.tech)