How to query whether a table is locked in Oracle

Oracle methods to query whether a table is locked include querying the DBA_OBJECTS view, querying the DBA_LOCKS view, querying the V$LOCKED_OBJECT view, querying the V$SESSION view, querying the DBA_BLOCKERS and DBA_WAITERS views. Detailed introduction: 1. Use the DBA_OBJECTS view, If the value of the OBJECT_TYPE column in the returned result is "TABLE", it means that the table is locked; 2. Query the DBA_LOCKS view, etc.

The operating environment of this tutorial: Windows 10 system, Oracle version 19c, DELL G3 computer.

Oracle database provides multiple methods to query whether a table is locked. The following are some commonly used methods:

1. Query the DBA_OBJECTS view:

You can use the OBJECT_NAME and OBJECT_TYPE columns in the DBA_OBJECTS view to query whether the table is locked. If the table is locked, then the value of the OBJECT_TYPE column will be 'TABLE', otherwise it will be some other value.

SELECT OBJECT_NAME, OBJECT_TYPE
FROM DBA_OBJECTS
WHERE OBJECT_NAME = '表名';

If the value of the OBJECT_TYPE column in the returned result is 'TABLE', it means that the table is locked.

2. Query the DBA_LOCKS view:

You can use the DBA_LOCKS view to query the locking information in the database. By querying this view, you can learn which tables are locked and the type of lock.

SELECT OBJECT_NAME, LOCK_TYPE
FROM DBA_LOCKS
WHERE OBJECT_NAME = '表名';

If there is a corresponding table name in the returned result, it means that the table is locked. The LOCK_TYPE column can tell you the type of lock, such as shared lock (Shared) or exclusive lock (Exclusive).

3. Query the V$LOCKED_OBJECT view:

The V$LOCKED_OBJECT view provides information about locked objects. By querying this view, you can learn which objects (including tables) are locked.

SELECT OBJECT_NAME
FROM V$LOCKED_OBJECT
WHERE OBJECT_NAME = '表名';

If there is a corresponding table name in the returned result, it means that the table is locked.

4. Query the V$SESSION view:

You can query the V$SESSION view to view the currently executing session information, including whether the session holds a lock.

SELECT s.SID, s.SERIAL#, s.STATUS, l.TYPE, l.LMODE, l.REQUEST
FROM V$SESSION s, V$LOCKED_OBJECT l
WHERE s.SID = l.SESSION_ID
AND l.OBJECT_NAME = '表名';

If the returned result contains corresponding session information, it means that the table is locked.

5. Query the DBA_BLOCKERS and DBA_WAITERS views:

You can use the DBA_BLOCKERS and DBA_WAITERS views to query session information that is currently waiting or holding locks. By querying these two views, you can learn which sessions are waiting for or holding locks on the table.

SELECT b.SID, b.SERIAL#, b.ORACLE_USERNAME, w.SID, w.SERIAL#, w.ORACLE_USERNAME
FROM DBA_BLOCKERS b, DBA_WAITERS w
WHERE b.SID = w.BLOCKING_SESSION
AND w.WAITING_SESSION = (SELECT SID FROM V$SESSION WHERE USERNAME = '用户名')
AND w.OBJECT_ID = (SELECT OBJECT_ID FROM DBA_OBJECTS WHERE OBJECT_NAME = '表名');

If the returned result contains corresponding session information, it means that the table is locked.

The above are some common methods to query whether the table in the Oracle database is locked. Choose an appropriate method to query according to the actual situation in order to understand the lock status of the table.

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