4 ms·

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 i

• petergeoghegan 9y ago
  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.
  • skyde 9y ago
    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.