What is lock mode in DB2?
The mode of a lock tells what access to the locked object is permitted to the lock owner and to any concurrent processes. Db2 uses of the lock modes to determine whether one lock is compatible with another. Some lock modes do not exclude all other users.
What is lock mode?
Lock Modes. A lock has a mode that determines its power—whether it prevents other users from reading or changing the locked resource.
What are different types of locks in DB2?
DB2 supports locking at four levels, or granularities: table space-, table-, page-, and row-level locking. DB2 also provides LOB locking for large objects (BLOBs, CLOBs, and DBCLOBs). Locks can be taken at any level in the locking hierarchy without taking a lock at the lower level.
How do you check if DB2 table is locked?
Type “db2 list applications show detail” and look for your connection which will be in “lock wait” state. 3. Type “get snapshot for application ” where is the id of your connection which you found in step 2. At the bottom of the output, you’ll find which agent holds the lock on the table.
What is isolation level in Db2?
The isolation level determines the mode of page or row locking implemented by the program as it runs. Db2 supports a variation of the standard isolation levels. Db2 implements page and row locking at the program execution level, which means that all page or row locks are acquired as needed during the program run.
How does cursor work in Db2?
When your program issues a row-positioned FETCH statement, Db2 uses the cursor to point to a row in the result table, making it the current row. Db2 then moves the current row contents into the program host variables that you specified in the INTO clause of the FETCH statement. The FETCH statement moves the cursor.
What are the two modes of locking?
Two types of locks are used by the basic protocol: Shared and Exclusive locks.
How do you find deadlocks in Db2?
Detecting and managing deadlocks
- Right-click on the Lock icon and select Deadlock Detection.
- select one of the following commands from the submenu: Monitor Deadlocks. Pause Deadlock Detection. Resume Deadlock Detection. Stop Deadlock Detection. Show Deadlocks.
How does Cobol resolve deadlock in Db2?
Procedure
- Obtain information from the lock event monitor or administration notification log about all tables where agents are experiencing deadlocks.
- Use the information in the administration notification log to decide how to resolve the deadlock problem.
What is dirty read in DB2?
Since V4, DB2 has provided read-through locks, also know as “dirty read” or “uncommitted read,” to help overcome concurrency problems. When using an uncommitted reads an application program can read data that has been changed, but is not yet committed.
What is the difference between CS and RR isolation levels?
Under an RR isolation level all page locks are held until they are released by a COMMIT (or ROLLBACK), whereas with CS read-only page locks are released as soon as another page is accessed. Repeatable read is the default isolation level if none is specified at BIND time.