I think what your looking for is called range lock.
When a query sort or filter rows using a range predicate. If using repeatable read isolation. A range lock is created to detect conflict with another transaction inserting new matching row.
That's not how postgres works. You're talking about 2PL. Serializable isolation level in postgres does have something called predicate locks, but those are actually quite a different thing.
No I was talking exactly about Predicate Locking.
They detect writes which conflict with earlier reads I dont think this could be called 2PL because it's only used to detect conflict.
Correctness requires that any insert into an index generate a rw-conflict with a concurrent serializable transaction if, after that insert, re-execution of any index scan of the other transaction would access the heap for a row not accessed during the previous execution.
