Deadlock detected while waiting for resource
两个或多个会话之间形成了循环锁依赖，互相阻塞。Oracle 自动回滚其中一个会话的语句来解除死锁。
SELECT * FROM v$lock WHERE block = 1;-- Check for unindexed foreign keys:\nSELECT c.table_name, c.constraint_name, cc.column_name FROM dba_constraints c JOIN dba_cons_columns cc ON c.constraint_name = cc.constraint_name WHERE c.constraint_type = 'R' AND NOT EXISTS (SELECT 1 FROM dba_ind_columns ic WHERE ic.table_name = c.table_name AND ic.column_name = cc.column_name);