Identical created_at across rows often means one Postgres transaction

Before you conclude that rows with identical timestamps were backdated or imported with client-supplied dates, remember that Postgres now() (and DEFAULT now()) returns the transaction start time. Every row inserted in the same transaction gets the same value. So inspect the write path: if each insert runs in its own request and transaction with DEFAULT now(), identical timestamps across rows mean something else wrote them, such as a migration, a batch import or manual SQL. Use clock_timestamp() when you need a separate time for each row inside one transaction. Separately, the AWS CLI 'aws login' accepts --region, so a small shell function can make sign-in use another region without changing the profile's default region that other scripts rely on.