"Security"? This has nothing to do with security. Also, it's not great to pollute technical forums with more ChatGPT-generated content when it would be more useful for domain experts to contribute their own knowledge.
That aside, it’s blatantly against the rules here. Go somewhere else if you want botspam
Maybe you can't see dead comments?
In Postgresql, the default ISOLATION LEVEL is "READ COMMITTED", which by standard, allows "NON-REPEATABLE READ" phenomena.
When Transaction on the LEFT is COMMITTED (adding 100 to balance), the Transaction on the RIGHT will add 400 to a balance of 1100, and not to a balance of 1000 (reading NON-REPEATED value).
You can do better than leaving this kind of comment that does not contribute in anything.
Have good weekend.