Lock Object

[Former Member]

Can anyone tell me little more about Lock Objects?

[former_member182371]

Hi,

just have a look at SAP HELP:

http://help.sap.com/saphelp_nw70/helpdata/en/41/7af4c5a79e11d1950f0000e82de14a/content.htm

Best regards.

[Former Member]

Go to transaction SE11,

click on radio button lock objects and read documentation.

theres lots of information given.

Regards

[Former Member]

Lock mode

Defines how to synchronize table record access by several users

Exclusive lock or read lock

The locked data can be read or processed by one user only. A request for another exclusive lock or for a shared lock is rejected.

Shared lock or write lock

Several users can read the same data at the same time, but as soon as a user edits the data, a second user can no longer access this data. Requests for further shared locks are accepted, even if they are issued by different users, but exclusive locks are rejected.

Exclusive but not cumulative lock

Exclusive locks can be requested by the same transaction more than once and handled successively, but an exclusive but not cumulative lock can only be requested once by a given transaction. All other lock requests are rejected

Main purpose: If multiple user try to access a database object, inconsistency may occer. To avoid that inconsistency and to let multiple user give the accessibility of the database objects the locking mechanism is used.

Steps: first we create a loc object in se11 . Suppose for a table mara. It will create two functional module.:

1. enque_lockobject

1. deque_lockobject

before updating any table first we lock the table by calling enque_lockobject fm and then after updating we release the lock by deque_lockobject.

[Former Member]

Lock objects are use in SAP to avoid the inconsistancy at the time of data is being insert/change into database.

SAP Provide three type of Lock objects.

- Read Lock(Shared Locked) - protects read access to an object. The read lock allows other transactions read access but not write access to the locked area of the table

- Write Lock(exclusive lock) - protects write access to an object. The write lock allows other transactions neither read nor write access to the locked area of the table.

- Enhanced write lock (exclusive lock without cumulating) -works like a write lock except that the enhanced write lock also protects from further accesses from the same transaction.

You can create a lock on a object of SAP thorugh transaction SE11 and enter any meaningful name start with EZ Example EZTEST_LOCK.

Use: you can see in almost all transaction when you are open an object in Change mode SAP could not allow to any other user to open the same object in change mode.

Example: in HR when we are enter a personal number in master data maintainance screen SAP can't allow to any other user to use same personal number for changes.

Technicaly:

When you create a lock object System automatically creat two function module.

1. ENQUEUE_<Lockobject name>. to insert the object in a queue.

2. DEQUEUE_<Lockobject name>. To remove the object is being queued through above FM.

You have to use these function module in your program.

Also check this link.

http://help.sap.com/saphelp_nw70/helpdata/en/41/7af4c5a79e11d1950f0000e82de14a/content.htm

Regards,

Maha