ndbinfo: The NDB Cluster Information Database • lock_num • waiting_for • node_id • block_instance • transid 4528 Transaction ID LQH block instance Node ID of reporting LQH block The  cluster_operations  table contains the following columns: The  cluster_operations  table provides a per-operation (stateful primary key op) view of all activity in the NDB Cluster from the point of view of the local data management (LQH) blocks (see The DBLQH Block). The lock state is shown in the  lock_state  column; if this is  W , the lock is waiting to be granted, and the  waiting_for  column shows the lock ID of the lock object this request is waiting for. Otherwise, the waiting_for  column is empty.  waiting_for  can refer only to locks on the same row, as identified by node_id ,  block_instance ,  tableid ,  fragmentid , and  rowid . The lock ID ( lockid  column) is unique to this node and block instance. The  duration_millis  column shows the number of milliseconds for which this lock request has been waiting or holding the lock. This is reset to 0 when a lock is granted for a waiting request. The  op  column shows the type of operation requesting the lock. This is always one of the values  READ , INSERT ,  UPDATE ,  DELETE ,  SCAN , or  REFRESH . When the  detail  column contains a  *  (asterisk character), this means that this lock is the first holding lock in the affected row’s lock queue; otherwise, this column is empty. This information can be used to help identify the unique entries in a list of lock requests. The  state  column shows the lock state. Its value is always one of  H  (holding) or  W  (waiting). A waiting lock request waits for a lock held by a different transaction. The  mode  column shows the lock mode; this is always one of  S  (indicating a shared lock) or  X  (an exclusive lock). If a transaction holds an exclusive lock on a given row, all other locks on that row have the same transaction ID. The transaction ID ( transid  column) is the identifier generated by the NDB API for the transaction requesting or holding the current lock. The table ID ( tableid  column) is assigned internally, and is the same as that used in other  ndbinfo tables. It is also shown in the output of  ndb_show_tables . Waiting for lock with this ID ID of lock object Notes 23.5.14.6 The ndbinfo cluster_operations Table