Oracle Database 11gR2 Performance Tuning Cookbook

V$LOCK

This view lists the locks held by the database.

Fields

The most relevant view fields are:

• SID: An identifier for the session holding or acquiring the lock
• ID1: Lock identifier #1 (depends on TYPE)
• ID2: Lock identifier #2 (depends on TYPE)
• TYPE: The type of lock; user locks can be TM (DML enqueue), TX (transaction enqueue), or UL (user supplied)
• LMODE: A lock mode in which the session holds the lock; values can be:
  • NONE
  • NULL (NULL)
  • ROW-S (SS)
  • ROW-X
  • SHARE (S)
  • S/ROW-X (SSX)
  • EXCLUSIVE (X)
• REQUEST: A lock mode in which the process request locks; values are the same as for the LMODE field
• CTIME: The time since current mode was granted
• BLOCK: If the lock is blocking another lock the value is 1, otherwise the value is 0

See also

• The DBA_BLOCKERS, DBA_WAITERS, ...