Repeatable Read Isolation Level "transaction start time"

https://www.postgresql.org/docs/16/transaction-iso.html#XACT-REPEATABLE-READ The PostgreSQL documentation for the Repeatable Read Isolation Level states the following: “UPDATE, DELETE, MERGE, SELECT FOR UPDATE, and SELECT FOR SHARE commands behave the same as SELECT in terms of searching for ta

pg_locks in production

If performance is not an issue, is it valid to use the pg_locks system view in production code? Or are there other concerns besides performance that would make its use inappropriate for production?

CREATE DATABASE command concurrency

What are the concurrency guarantees of the CREATE DATABASE command? For example, is the CREATE DATABASE command safe to be called concurrently such that one command succeeds and the other reliably fails without corruption?