> [!NOTE] ![[assets/wl_lwlock_predicatelockmanager.png|256]] > > | | | > | :--- | :--- | > | **Wait Category** | LWLock | > | **Mechanism** | `PredicateLockManagerLock` | > | **Operations** | [[Operations/Table/SeqScan]], [[Operations/Index/IndexScan]] | > | **Resources** | [[Resources/RAM|Memory]], [[Resources/CPU|CPU]] | > > **SSI Coordination Bottleneck**. Unlike standard locks (which protect physical rows), predicate locks protect "gaps" in the data, ensuring that no concurrent transaction can insert a row that would change the result of a previously executed query.