> [!NOTE] ![[assets/wl_lwlock_serializablepredicatelist.png|256]] > > | | | > | :--- | :--- | > | **Wait Category** | LWLock | > | **Mechanism** | `SerializablePredicateListLock` | > | **Operations** | [[Operations/Table/SeqScan]], [[Operations/Index/IndexScan]] | > | **Resources** | [[Resources/RAM|Memory]], [[Resources/CPU|CPU]] | > > **SSI Session Metadata Access Barrier**. Every `SERIALIZABLE` transaction maintains a private (but in shared memory) list of all the gaps and rows it has touched, which must be scanned during conflict detection.