Oracle Skip Locked

Oracle Skip Locked [html] Oracle Skip Locked Oracle 11g introduces skip locked. Skip Locked is used to Skip the rows that have been Locked by other query select statements in the query select statement, and only execute the rows that can obtain the lock. Select for update how to query a large number, then the select statement executed by other sessions at the same time may wait for the lock timeout and report the following error ORA-30006: resource busy; acquire with WAIT timeout expired if it is not time-out case, then the ORA-00054 resource busy and NOWAIT specified such as session1 will execute the following statement: SELECT * FROM dept WHERE deptno = 10 for update nowait; output: deptno dname loc ---------- -------------- ------------- 10 accounting new york session2 execute the following statement: SELECT * FROM dept WHERE deptno IN (10, 20) for update nowait; then the output: SELECT * FROM dept WHERE deptno IN () for update nowait error at line 1: ORA-00054: resource busy and acquire with NOWAIT specified because session1 has locked the row 10, and session2 requests to get the lock of less than 10, an error is returned. IN session2, we can use skip locked SELECT * FROM dept WHERE deptno IN () for update skip locked. At this time, the output is: deptno dname loc ---------- ------------ --------------- 20 research dallas skip locked skips the LOCKED rows and queries only the rows that are not LOCKED.