Several ways to query table lock status in Oracle

Title: Several ways to query table lock status in Oracle

In Oracle database, table lock is an important database lock, used to control the access to database tables of concurrent access. When multiple users access the same table at the same time, table locks may occur, causing some users to be blocked or have performance problems. In order to discover and solve table lock problems in a timely manner, we can query the table lock situation in a variety of ways. Below we will introduce several common methods and attach specific code examples.

1. Query the lock information of the current session

You can query the object information locked by the current session through the following SQL statement:

SELECT
   O.OBJECT_NAME,
   O.OBJECT_TYPE,
   S.SID,
   S.SERIAL#,
   S.LOGON_TIME
FROM
   V$LOCK L
   JOIN ALL_OBJECTS O ON L.ID1 = O.OBJECT_ID
   JOIN V$SESSION S ON L.SID = S.SID
WHERE
   O.OBJECT_TYPE = 'TABLE';

This query will list the locks of all current tables Information, including the object name of the locked table, the object type to which the table belongs, session ID, serial number and login time, etc.

2. Query table-level lock information

You can query the lock information of a certain table through the following SQL statement:

SELECT
   L.SID,
   S.SERIAL#,
   S.LOGON_TIME
FROM
   V$LOCK L
   JOIN V$SESSION S ON L.SID = S.SID
   JOIN ALL_OBJECTS O ON L.ID1 = O.OBJECT_ID
WHERE
   O.OBJECT_NAME = 'TABLE_NAME'
   AND O.OBJECT_TYPE = 'TABLE';

Among them, replace ' in the above code Replace TABLE_NAME' with the name of the table you want to query, and you can view the lock information of the table.

3. Query the waiting session for table lock

The following SQL statement can be used to query the session information currently waiting for a table lock:

SELECT
   L.SID,
   S.SERIAL#,
   S.LOGON_TIME
FROM
   V$LOCK L
   JOIN V$SESSION S ON L.SID = S.SID
   JOIN ALL_OBJECTS O ON L.ID1 = O.OBJECT_ID
WHERE
   O.OBJECT_NAME = 'TABLE_NAME'
   AND O.OBJECT_TYPE = 'TABLE'
   AND L.TYPE = 'TM';

Similarly, add the code in Replace 'TABLE_NAME' with the name of the table you want to query, and you can view the session information currently waiting for the table lock.

Through the above methods, we can quickly and accurately query the table lock situation in the Oracle database, helping us to discover and solve table lock problems in a timely manner to ensure the normal operation of the database system.

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