> [!NOTE] ![[assets/wl_lwlock_procarray.png|256]] > > | | | > | :--- | :--- | > | **Wait Category** | LWLock | > | **Mechanism** | `ProcArrayLock` | > | **Operations** | [[Operations/Table/SeqScan]], [[Operations/Tuple/ModifyTable]] | > | **Resources** | [[Resources/RAM|Memory]], [[Resources/CPU|CPU]] | > > Contention on the **Global Visibility Coordinator**. Every time a query starts, it must take a "Snapshot" to determine which transactions were already committed and which are still in-flight; this requires scanning the entire `ProcArray` while holding this lock.