Collections:
Show Existing Locks on the Database in Oracle
How To View Existing Locks on the Database in Oracle?
✍: FYIcenter.com
As can see from the pervious tutorial exercise, performance of the second session is greatly affected by the data lock created on the database. To maintain a good performance level for all sessions, you need to monitor the number of data locks on the database, and how long do they last.
Oracle maintains current existing data locks in a Dynamic Performance View called V$LOCK with columns like:
The following tutorial exercise shows you how to view existing locks on the database:
(session 1) SQL> connect HR/fyicenter SQL> UPDATE fyi_links SET url='centerfyi.com' WHERE id=110; 1 row updated. (session 2) SQL> connect HR/fyicenter SQL> INSERT INTO fyi_links (url, id) VALUES ('oracle.com', 112); 1 row created. SQL> UPDATE fyi_links SET notes='FYI Resource' WHERE id=110; (wait on lock at id=110)
Now keep those two sessions as is. You need to open a third window to connect to the database as SYSTEM to view all current locks:
(session 3) SQL> connect SYSTEM/password SQL> select sid, username from v$session 2 where username='HR'; SID USERNAME ---------- ------------------------------ 23 HR 39 HR SQL> SELECT sid, type, lmode, request, ctime, block FROM V$LOCK WHERE sid in (23, 39) ORDER BY ctime DESC; SID TY LMODE REQUEST CTIME BLOCK ---- -- ---------- ---------- ---------- ---------- 1 39 TX 6 0 84 1 2 39 TM 3 0 84 0 3 23 TM 3 0 27 0 4 23 TX 6 0 27 0 5 23 TX 0 6 18 0
You should read the output as:
Â
2019-08-08, 1094👍, 0💬
Popular Posts:
What Are the Underflow and Overflow Behaviors on FLOAT Literals in SQL Server Transact-SQL? If you e...
How to set database to be READ_ONLY in SQL Server? Databases in SQL Server have two update options: ...
How To List All User Names in a Database in SQL Server? If you want to see a list of all user names ...
Where to find answers to frequently asked questions on Installing Sample Scripts and Databases in SQ...
What is sqlservr.exe - Process - SQL Server (SQLEX?PRESS) in SQL Server? Process sqlservr.exe is the...