What is LUW?

Hi,
Could you please explain me abt LUW (Logical Unit of Work) and send me the related documents also.
Regards,
Ramganesan.

Hi Ramganesan,
Check this.
A Logical Unit of Work (LUW or database transaction) is an inseparable sequence of database operations which must be executed either in its entirety or not at all. For the database system, it thus constitutes a unit.
LUWs help to guarantee database integrity. When an LUW has been successfully concluded, the database is once again in a correct state. If, however, an error occurs within an LUW, all database changes made since the beginning of the LUW are canceled and the database is then in the same state as before the LUW started.
An LUW begins
o each time you start a transaction
o when the database changes of the previous LUW have been confirmed (database
commit) or
o when the database changes of the previous LUW have been cancelled (database rollback)
An LUW ends
o when the database changes have been confirmed (database commit) or
o when the database changes have been canceled (database rollback)
COMMIT WORK.
Executes a database commit and thus closes a logical processing unit or Logical Unit of Work ( LUW ) (see also Transaction processing ). This means that
all database changes are made irrevocable and cannot be reversed with ROLLBACK WORK and
all database locks are released.
COMMIT WORK also
calls the subroutines specified by PERFORM ... ON COMMIT * executes asynchronously any update requests (see CALL FUNCTION ... IN UPDATE TASK ) specified in these subroutines or started just before,
processes the function modules specified in CALL FUNCTION ... IN BACKGROUND TASK ,
cancels all existing locks (see SAP locking concept ) if no update requests exist,
closes all open database cursors (see OPEN CURSOR ) and
resets the time slice counter to 0.
COMMIT WORK belongs to the Open SQL command set.
Return code value
The SY-SUBRC is set to 0.
ROLLBACK WORK.
Closes a logical processing unit by reversing all database changes made since the last COMMIT .
You use this statement if you cannot be certain that all the database changes have been executed correctly.
The update routines are not performed.
ROLLBACK WORK belongs to the Open SQL command set.
Note
If the ROLLBACK statement occurs within a SELECT loop, the processing cannot continue because the database cursor is invalid. After the ROLLBACK statement, you should therefore ensure that all SELECT processing has been explicitly terminated.
A detailed documentation for the LUWs.
http://help.sap.com/saphelp_nw04/helpdata/en/41/7af4bfa79e11d1950f0000e82de14a/content.htm
Reward If Useful.
Regards,
Chitra

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What is luw (logical unit of work)

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hi,
this gives complete idea
SAP LUW
Since, as a rule, an application program is processed by several work processes in succession, and every change of the work process is linked with an implicit database commit , an application program is not automatically linked with a single database LUW. This applies in particular to dialog-oriented applications, in which one database LUW is assigned to one dialog step.
To ensure the data consistency of application programs that are executed across different work processes, the application statements are not directly executed in an SAP LUW, rather, are first registered and then executed by a single work process, that is, in a single database LUW.
Two techniques are available for bundling the change statements in a database LUW:
Bundling via function modules (update)
Through the statement CALL FUNCTION...IN UPDATE TASK, an update function module is registered for subsequent execution in an update work process.
Bundling via function modules (transactional RFC)
Through the statement CALL FUNCTION... IN BACKGROUND TASK DESTINATION, a remote- compatible function module is registered for subsequent asynchronous execution via the RFC interface (transactional RFC ).
Bundling via subprograms
Through the statement PERFORM ... ON COMMIT, a subprogram is registered for subsequent execution in a different work process.
Statements for SAP LUWs
A SAP LUW is controlled via the Open SQL statements COMMIT WORK, ROLLBACK WORK and SET UPDATE TASK LOCAL.
Note
A function module can be classified either as an update function module or remote-compatible, but not both at the same time. The update helps realize SAP LUWs within an SAP System, while the transactional RFC creates LUWs in distributed systems.
COMMIT WORK
Variants:
1. COMMIT WORK [AND WAIT].
2. COMMIT CONNECTION con.
Effect
Terminates an SAP LUW and stores the changes.
Variant 1
COMMIT WORK [AND WAIT].
Effect
The statement COMMIT WORK completes the current SAP LUW and opens a new one, storing all change requests for the currenta SAP LUW in the process. In this case, COMMIT WORK performs the following actions:
It executes all subroutines registered using PERFORM ON COMMIT.
It triggers an internal event in Object Services that ensures the registration of changes in persistent objects as the last update function module, as well as the subsequent initialization of persistent object attributes.
It initiates the processing of all registered update function modules in the update work process.
This executes all high-priority update function modules registered using CALL FUNCTION ... IN UPDATE TASK in the order of their registration and in a common database LUW. If you do not specify the addition AND WAIT, the program does not wait until the update work process has executed it (asynchronous updating). If you specify the addition AND WAIT, however, program processing after COMMIT WORK will not continue until the update work process has executed the high-priority update function modules (synchronous updating).
If all high-priority update function modules are completed successfully, the statement executes the low-priority update function modules together in a common database LUW.
In parallel, it also executes the individual function modules registered using CALL FUNCTION ... IN BACKGROUND TASK DESTINATION in a separate database LUW for each destination.
It handles all SAP locks set in the current program according to the value of the formal parameter _SCOPE of the corresponding lock function modules.
It triggers a database commit that also terminates the current database LUW.
The completion of statement COMMIT WORK triggers the event TRANSACTION_FINISHED of the system class CL_SYSTEM_TRANSACTION_STATE, where the parameter KIND has the value of the constant CL_SYSTEM_TRANSACTION_STATE=>COMMIT_WORK.
If the statement COMMIT WORK is executed by calling special programs, be aware of the following:
In a program executed using batch input, or if you have called the program using the USING addition of the statement CALL TRANSACTION, COMMIT WORK terminates the batch input processing when using the corresponding settings.
In a program called using CALL DIALOG, COMMIT WORK initiates the processing of subroutines or updated function modules registered using PERFORM ... ON COMMIT and CALL FUNCTION ... IN UPDATE TASK. Therefore, it does not complete the current SAP LUW. The SAP LUW cannot be completed until you execute the COMMIT WORK statement in the calling program.
You cannot execute the COMMIT WORK statement during the updating procedure or during the execution of subroutines registered using PERFORM ... ON {COMMIT|ROLLBACK}.
System fields
sy-subrc Meaning
0 You have specified the AND WAIT addition, and the updating of the update function modules was successful.
4 You have specified the AND WAIT addition, and the updating of the update function modules was not successful.
The COMMIT WORK statement always sets sy-subrc to 0 if the AND WAIT addition is not specified.
Note
The COMMIT WORK statement closes all database cursors . Open SQL statements that access a database cursor later ( SELECT loop and FETCH) raise an exception that cannot be handled.
Variant 2
COMMIT CONNECTION con.
Note
This statement is for internal use only.
It cannot be used in application programs.
Effect
The COMMIT command is not executed on the standard database, but only on the secondary database connection specified by con. con is the name of the database connection as it was specified in the table DBCON in the column CON_NAME. The database connection con can also be specified dynamically in the form (source_text) - the source_text field contains the name of the database connection. The source_text field must be of the type C or STRING.
On the specified secondary database connection, the database commit:
Closes all open database cursors (OPEN CURSOR)
Releases all database locks
Note
Note that the COMMIT CONNECTION DEFAULT statement unlike COMMIT WORK executes a pure database commit on the DEFAULT connection.
Exceptions
Non-Catchable Exceptions
Cause: COMMIT WORK is not possible in a FORM that was called using PERFORM ... ON COMMIT.
Runtime Error: COMMIT_IN_PERFORM_ON_COMMIT
Cause: COMMIT WORK is not allowed in the update.
Runtime Error: COMMIT_IN_POSTING
ROLLBACK WORK
Variants:
1. ROLLBACK WORK.
2. ROLLBACK CONNECTION con.
Effect
Terminates a SAP-LUW without storing the changes.
Variant 1
ROLLBACK WORK.
Effect
The statement ROLLBACK WORK closes the current SAP-LUW and opens a new one. In doing so, all change requests of the current SAP-LUW are canceled. To do this, ROLLBACK WORK carries out the following actions:
Executes all subprograms registered with PERFORM ON ROLLBACK.
Deletes all subprograms registered with PERFORM ON COMMIT.
Raises an internal exception in the Object Services that makes sure that the attributes of persistent objects are initialised.
Deletes all update function modules registered with CALL FUNCTION ...IN UPDATE TASK from the VBLOG and deletes all transactional remote Function Calls registered with CALL FUNCTION ... IN BACKGROUND TASK from ARFCSSTATE and from ARFCSDATA.
Removal of all SAP locks set in the current program in which the formal parameter _SCOPE of the lock function module was set to the value 2.
Triggers a database rollback, which also ends the current database-LUW.
After completion of the statement COMMIT WORK, the event TRANSACTION_FINISHED of the system class CL_SYSTEM_TRANSACTION_STATE is raised, in which the parameter KIND has the value of the constant CL_SYSTEM_TRANSACTION_STATE=>ROLLBACK_WORK.
Variant 2
ROLLBACK CONNECTION con.
Note
This statement is for internal use only.
It cannot be used in application programs.
Effect
The ROLLBACK-statement is not executed on the standard database but only on the secondary database connection, specified through con. con is the name of the database connection as it was specified in table DBCON in column CON_NAME. The database connection con can also be specified dynamically in the form (source_text), in which the field source_text contains the name of the database connection. The field source_text must be of the type C or STRING.
Notes
As all opened database cursors on the respective database connections are closed at ROLLBACK, the attempt to continue a SELECT-loop after a ROLLBACK, leads to a runtime error. Due to the same reason, a FETCH after a ROLLBACK to the then closed cursor, leads to a runtime error. You have to make sure that cursors that are still open, are no longer used after ROLLBACK.
After execution of the statement ROLLBACK, SY-SUBRC is always equal to 0. It is not necessary to check if SY-SUBRC is unequal to 0 after ROLLBACK.
ROLLBACK must not be used during update (CALL FUNCTION ... IN UPDATE TASK) or during the execution of FORMs, which were registered with PERFORM ... ON COMMIT resp. PERFORM ...ON ROLLBACK.
The statement ROLLBACK WORK is implicitly executed if a message of the type A is treated with the addition ERROR_MESSAGE when calling a function module with CALL FUNCTION.
Exceptions
Non-Catchable Exceptions
Cause: ROLLBACK WORK is not allowed within a FORM that is called with PERFORM ... ON COMMIT or PERFORM ... ON ROLLBACK.
Runtime Error: ROLLBACK_IN_PERFORM_ON_COMMIT
Cause: ROLLBACK WORK is not allowed within an update.
Runtime Error: ROLLBACK_IN_POSTING
SET UPDATE TASK LOCAL
Syntax
SET UPDATE TASK LOCAL.
Effect
This statement specifies that the high-priority update function modules - registered during the current SAP LUW using CALL FUNCTION ... IN UPDATE TASK - are registered in the ABAP memory instead of the VBLOG database table. In addition, it specifies that the current work process and not the update work process run these modules during the current database LUW, when the COMMIT WORK statement is executed. This statement has no effect on low-priority update function modules.
At the beginning of every SAP LUW, the local update function is deactivated. If you wish to use it, you must reactivate it again before the first update function module is registered.
System fields
sy-subrc Meaning
0 The local update function is activated.
1 The local update function has not been activated, because the program has already registered at least one update function module for the normal updating procedure in the current SAP-LUW.
Notes
The local update function performs a synchronous update according to the COMMIT WORK statement, independent of the addition AND WAIT.
The occurrence of a database rollback during the local update affects all previous change requests.

Can somebody explain what is LUW ?

Hi Gurus,
can somebosy explain me what is LUW(Logical unit of work).
I went through some book, but i am not able to get the concept.
can somebody help me out inthis
Thanks & regards
Rajesh Meda

hello Rajesh,
Did you go this through this:
http://help.sap.com/saphelp_nw04s/helpdata/en/41/7af4bfa79e11d1950f0000e82de14a/content.htm
Check this out.
Anyways as you know in SAP the user acting a presentation level tries to read/write data from database using SAP application layer. This entire activity consists of several dialog steps (small activities if you may) and is termed as a LUW. So an SAP LUW consists of several dialog steps which are dependent on each other. Only if all are completed is a LUW executed successfully and in case of any failures entire thing is roll backed and terminated.
Regards.
Ruchit.

What is LUW? How do we use it in SAP ABAP coding?

Hi Friends,
Kindly explain me what is LUW with examples and how do we use it in our ABAP coding with scenarios why and when we use it?
Regards,
Pradeep

Hi,
SAP LUW
Die Verbuchungsverwaltung
The Open SQL statements INSERT, UPDATE, MODIFY, and DELETE allow you to program database changes that extend over several dialog steps. Even if you have not explicitly programmed a database commit, the implicit database commit that occurs after a screen has been processed concludes the database LUW. The following diagram shows the individual database LUWs in a typical screen sequence:
Under this procedure, you cannot roll back the database changes from previous dialog steps. It is therefore only suitable for programs in which there is no logical relationship between the individual dialog steps.
However, the database changes in individual dialog steps normally depend on those in other dialog steps, and must therefore all be executed or rolled back together. These dependent database changes form logical units, and can be grouped into a single database LUW using the bundling techniques listed below.
A logical unit consisting of dialog steps, whose changes are written to the database in a single database LUW is called an SAP LUW. Unlike a database LUW, an SAP LUW can span several dialog steps, and be executed using a series of different work processes. If an SAP LUW contains database changes, you should either write all of them or none at all to the database. To ensure that this happens, you must include a database commit when your transaction has ended successfully, and a database rollback in case the program detects an error. However, since database changes from a database LUW cannot be reversed in a subsequent database LUW, you must make all of the database changes for the SAP LUW in a single database LUW. To maintain data integrity, you must bundle all of you database changes in the final database LUW of the SAP LUW. The following diagram illustrates this principle:
Database Logical Unit of Work (LUW)
From the point of view of database programming, a database LUW is an inseparable sequence of database operations that ends with a database commit. The database LUW is either fully executed by the database system or not at all. Once a database LUW has been successfully executed, the database will be in a consistent state. If an error occurs within a database LUW, all of the database changes since the beginning of the database LUW are reversed. This leaves the database in the state it was in before the transaction started.
The database changes that occur within a database LUW are not actually written to the database until after the database commit. Until this happens, you can use a database rollback to reverse the changes. In the R/3 System, database commits and rollbacks can be triggered either implicitly or using explicit commands.
Implicit Database Commits in the R/3 System
A work process can only execute a single database LUW. The consequence of this is that a work process must always end a database LUW when it finishes its work for a user or an external call. Work processes trigger an implicit database commit in the following situations:
When a dialog step is completed
Control changes from the work process back to the SAP GUI.
When a function module is called in another work process (RFC).
Control passes to the other work process.
When the called function module (RFC) in the other work process ends.
Control returns to the calling work process.
When a WAIT statement interrupts the work process.
Control passes to another work process.
Error dialogs (information, warning, or error messages) in dialog steps.
Control passes from the work process to the SAP GUI.
Explicit Database Commits in the R/3 System
There are two ways to trigger an explicit database commit in your application programs:
Call the function module DB_COMMIT
The sole task of this function module is to start a database commit.
Use the ABAP statement COMMIT WORK
This statement starts a database commit, but also performs other tasks (refer to the keyword documentation for COMMIT WORK).
Implicit Database Rollbacks in the R/3 System
The following cases lead to an implicit database rollback:
Runtime error in an application program
This occurs whenever an application program has to terminate because of an unforeseen situation (for example, trying to divide by zero).
Termination message
Termination messages are generated using the ABAP statement MESSAGE with the message type A or X. In certain cases (updates), they are also generated with message types I, W, and E. These messages end the current application program.
Explicit Database Rollbacks in the R/3 System
You can trigger a database rollback explicitly using the ABAP statement ROLLBACK WORK. This statement starts a database rollback, but also performs other tasks (refer to the keyword documentation for COMMIT WORK).
From the above, we can draw up the following list of points at which database LUWs begin and end.
A Database LUW Begins
Each time a dialog step starts (when the dialog step is sent to the work process).
Whenever the previous database LUW ends in a database commit.
Whenever the previous database LUW ends in a database rollback.
A Database LUW Ends
Each time a database commit occurs. This writes all of the changes to the database.
Each time a database rollback occurs. This reverses all of the changes made during the LUW.
Database LUWs and Database Locks
As well as the database changes made within it, a database LUW also consists of database locks. The database system uses locks to ensure that two or more users cannot change the same data simultaneously, since this could lead to inconsistent data being written to the database. A database lock can only be active for the duration of a database LUW. They are automatically released when the database LUW ends. In order to program SAP LUWs, we need a lock mechanism within the R/3 System that allows us to create locks with a longer lifetime (refer to The R/3 Locking Concept).
The bundling technique for database changes within an SAP LUW ensures that you can still reverse them. It also means that you can distribute a transaction across more than one work process, and even across more than one R/3 System. The possibilities for bundling database changes within an SAP LUW are listed below:
The simplest form of bundling would be to process a whole application within a single dialog step. Here, the system checks the users input and updates the database without a database commit occurring within the dialog step itself. Of course, this is not suitable for complex business processes. Instead, the R/3 Basis system contains the following bundling techniques.
Bundling using Function Modules for Updates
If you call a function module using the CALL FUNCTION... IN UPDATE TASK statement, the function module is flagged for execution using a special update work process. This means that you can write the Open SQL statements for the database changes in the function module instead of in your program, and call the function module at the point in the program where you would otherwise have included the statements. When you call a function module using the IN UPDATE TASK addition, it and its interface parameters are stored as a log entry in a special database table called VBLOG.
The function module is executed using an update work process when the program reaches the COMMIT WORK statement. After the COMMIT WORK statement, the dialog work process is free to receive further user input. The dialog part of the transaction finishes with the COMMIT WORK statement. The update part of the SAP LUW then begins, and this is the responsibility of the update work process. The SAP LUW is complete once the update process has committed or rolled back all of the database changes.
For further information about how to create function modules for use in update, refer to Creating Function Modules for Database Updates
During the update, errors only occur in exceptional cases, since the system checks for all logical errors, such as incorrect entries, in the dialog phase of the SAP LUW. If a logical error occurs, the program can terminate the update using the ROLLBACK WORK statement. Then, the function modules are not called, and the log entry is deleted from table VBLOG. Errors during the update itself are usually technical, for example, memory shortage. If a technical error occurs, the update work process triggers a database rollback, and places the log entry back into VBLOG. It then sends a mail to the user whose dialog originally generated the VBLOG entry with details of the termination. These errors must be corrected by the system administrator. After this, the returned VBLOG entries can be processed again.
For further information about update administration, see Update Administration
This technique of bundling database changes in the last database LUW of the SAP LUW allows you to update the database asynchronously, reducing the response times in the dialog work process. You can, for example, decouple the update entirely from the dialog work process and use a central update work process on a remote database server.
Bundling Using Subroutines
The statement PERFORM ON COMMIT calls a subroutine in the dialog work process. However, it is not executed until the system reaches the next COMMIT WORK statement. Here, as well, the ABAP statement COMMIT WORK defines the end of the SAP LUW, since all statements in a subroutine called with PERFORM ON COMMIT that make database changes are executed in the database LUW of the corresponding dialog step.
The advantage of this bundling technique against CALL FUNCTION... IN UPDATE TASK is better performance, since the update data does not have to be written into an extra table. The disadvantage, however, is that you cannot pass parameters in a PERFORM... ON COMMIT statement. Data is passed using global variables and ABAP memory. There is a considerable danger of data inconsistency when you use this method to pass data.
Bundling Using Function Modules in Other R/3 Systems
Function modules that you call using CALL FUNCTION... IN BACKGROUND TASK DESTINATION... are registered for background execution in another R/3 System when the program reaches the next COMMIT WORK statement (using Remote Function Call). After the COMMIT WORK, the dialog process does not wait for these function modules to be executed (asynchronous update). All of the function modules that you register in this way are executed together in a single database LUW. These updates are useful, for example, when you need to maintain identical data in more than one database.
For further details, refer to the keyword documentation.
For more details of RFC processing, refer to the Remote Communications section of the Basis Services documentation.
Pls. reward if useful....

PI Basis and LUWs

Please enlighten :
1) What is PI basis
2) What is LUW(Logical Unit of work)
In a Delta Q, I see that say for example
     DataSource                        LUWs                Actual number of records in DS
0Trans control                      634                      25,00,000 (2.5 million)
0Goods_MOV                      132                           20,000 (twenty thousand)
What is the relationship between actual number of records with the number of LUWs? How is this LUW calculated and displayed? Any setting/configuration involved?
Points will be assigned for useful answers.
Regards
Shivu

Hi..
i think so the delta is queued delta ..
Depending onthe application up to 10000 delta extractions of documents per data souce are summarized into one Luw .
with regards,
hari kv

Number of records in an LUW

Hi,
Im new to BI.
How many records can be there in an LUW?

Hi,
Please go through the below link same things has been discussed in it.
what is luw in delta queue
Hopefully it will give you some insight.
Regards,
AL

Luw plz help me

what is update task?
what is luw ? when it is created?

hI
If you call the function module IN UPDATE TASK..You have to give subsequent commit work statement to trigger the update module..
Ex..
CALL FUNCTION 'Y_SAVE_TEXT' IN UPDATE TASK
COMMIT WORK..
<b>COMMIT WORK</b>
Persistent Objects and COMMIT WORK
To apply the changes made to the runtime objects of persistent classes to the actual persistent objects in the database, execute the COMMIT WORK statement. (Alternatively, use COMMIT WORK AND WAIT or SET UPDATE TASK LOCAL). Unless you are executing an object-oriented transaction from within the Transaction Service, you must include the COMMIT WORK statement explicitly in the program. Otherwise, it is encapsulated in the Transaction Service. (If you explicitly include the COMMIT WORK statement as described here, the t op-level transaction runs in compatibility mode).
The function of the COMMIT WORK statement is extended when you use it in conjunction with Object Services. Before COMMIT WORK closes the SAP LUW and triggers an update, it calls internal methods of the Persistence Service. These methods bundle the changes made to managed objects of the Persistence Service and pass them to a special update function module using CALL FUNCTION ... IN UPDATE TASK. Thus the Persistence Service works with traditional update methods. The update module is usually registered after any update modules that have already been registered. The update is then triggered and the update task executes the update module in the order in which they were registered.
After the system executes the COMMIT WORK statement, it sets the attributes of each persistent object in the ABAP program to initial. (That is, it calls the IF_OS_STATE~INVALIDATE method).
Local Update
If you want to change managed objects directly, rather than using the update module, you must change the update mode of the implicitly used Transaction Service. That is, the following statements must be executed before the COMMIT WORK statement:
DATA TM type ref to IF_OS_TRANSACTION_MANAGER.
DATA T type ref to IF_OS_TRANSACTION.
TM = CL_OS_SYSTEM=>GET_TRANSACTION_MANAGER( ).
T = TM->GET_CURRENT_TRANSACTION( ).
T->SET_MODE_UPDATE( OSCON_DMODE_DIRECT ).
COMMIT WORK.
To ensure database consistency, the local update is activated internally using SET UPDATE TASK LOCAL. In such cases, the system raises an exception if there are already update modules registered in the update task. You can only register additional classical update modules after setting the mode. They will then also be updated locally.
REWARD IF USEFULL

Regarding LUW

can anybody tell me What is LUW and use of it?

Hi:
A Logical Unit of Work (LUW or database transaction) is an inseparable sequence of database operations which must be executed either in its entirety or not at all. For the database system, it thus constitutes a unit.
LUWs help to guarantee database integrity. When an LUW has been successfully concluded, the database is once again in a correct state. If, however, an error occurs within an LUW, all database changes made since the beginning of the LUW are canceled and the database is then in the same state as before the LUW started.
An LUW begins
o Each time you start a transaction
o When the database changes of the previous LUW have been confirmed (database commit) or
o When the database changes of the previous LUW have been cancelled (database rollback)
An LUW ends
o When the database changes have been confirmed (database commit) or
o When the database changes have been canceled (database rollback)
Regards,
Sookshma

LBWF &LUW

HI ALL
1.what is LUW? what is the use,,& where we used ?
2.what is use of LBWF(bw log) in LO? why &where we used ?
any one tell me scenario of these two pls...
thnks

Hi Trupti,
Go through this url for LUW:
http://help.sap.com/saphelp_nw2004s/helpdata/en/41/7af4bfa79e11d1950f0000e82de14a/content.htm
Hope this helps.
Regards
Rahul Bindroo

LUWF & LUW

HI ALL
1.what is LUW? what is the use,,& where we used ?
2.what is use of LBWF(bw log) in LO? why &where we used ?
any one tell me scenario of these two pls...
thnks

LUW
Let one user is modifying a record and the second user is trying to delete the same record at the same time.
If the second user is successful in deleting the record, then the first user will face problem in modifying the record.
To avoid such problems, SAP has introduced LUW (Logical unit of Work)
LUW is defined as Locking Mechanism to protect transaction integrity.
Types of LUWs:
Database transaction or LUW.
Update transaction or SAPLUW.
ABAP/4 Transaction.
database transaction
Database transaction or LUW is defined as a period in which operation requested must be performed as one unit.
At the end of LUW, either the database changes are committed or rolled back.
SAP LUW
One SAP LUW can have several databases LUW. So a set of database transactions either committed or rolled back.
The special ABAP/4 command Commit work marks the end of SAP LUW.
ABAP/4 Transaction
It is made up of a set of related task combined under one transaction code.
ABAP/4 transaction functions like one complete object containing screens, menus and transaction code.
Check this documentation..
http://help.sap.com/saphelp_nw04/helpdata/en/41/7af4bfa79e11d1950f0000e82de14a/content.htm
And LBWF is the LO's log where yoou can find the info about all the extraction related tasks.
Assign points if usefull
Regards,

Partiotning, pseudo delta, LUW

Hi gurus,
could you please tell me
how PSA partiotining done. need steps to do it. How is cube partioitning done .need steps.
what is pseudo delta and where is it done , please tell me the steps to do it
What is LUW abbriviation, and whai is its functionality in BW and R/3
thanks in advance
regards

Hi Chaudary,
PSA Partition will be done automatically also in the transaction RSCUSTV6 you could set Packet size and Partition size.
And you can partition InfoCubes using two characteristics calendar month (0CALMONTH) and fiscal year/period (0FISCPER). The special feature of the fiscal year/period characteristic (0FISCPER) being compounded with the fiscal year variant (0FISCVARNT) means that you have to use a special procedure when you partition an InfoCube using 0FISCPER.
You use partitioning to split the total dataset for an InfoCube into several, smaller, physically independent and redundancy-free units.
http://help.sap.com/saphelp_erp2005/helpdata/en/0a/cd6e3a30aac013e10000000a114084/frameset.htm
Partitioning infocube :
http://www.crmexpertonline.com/archive/Volume_01_(2005)/Issue_01_(October)/v1i1a1.cfm?session=
PPT:http://www.cs.utk.edu/~huangj/CS594S02/infovis.ppt
Hope The above two links (article and ppt) helps you to understand ..
Pseudo delta is used with generic extractors, to make a a generic extactor delta enabled ...In RSO2 after creating the datasource at the top of the screen you have "Generic delta" icon, click on this & in the following screen you need to select the field on which the delta is to be performed along with the type of delta i.e Numeric or time stamp or on 0calday.
Save the datasource & relicate it in the BW system.
A Logical Unit of Work (LUW or database transaction) is an inseparable sequence of database operations which must be executed either in its entirety or not at all. For the database system, it thus constitutes a unit.
LUWs help to guarantee database integrity. When an LUW has been successfully concluded, the database is once again in a correct state. If, however, an error occurs within an LUW, all database changes made since the beginning of the LUW are canceled and the database is then in the same state as before the LUW started.
An LUW begins
o each time you start a transaction
o when the database changes of the previous LUW have been confirmed (database commit) or
o when the database changes of the previous LUW have been cancelled (database rollback)
An LUW ends
o when the database changes have been confirmed (database commit) or
o when the database changes have been canceled (database rollback)
Points = thanks,
Regards
Message was edited by:
samara reddy

About LUW

Hi experts,
any body please tell me what is LUW and what is need of it inABAP pro

Hi,
Database Logical Unit of Work (LUW)
From the point of view of database programming, a database LUW is an inseparable sequence of database operations that ends with a database commit. The database LUW is either fully executed by the database system or not at all. Once a database LUW has been successfully executed, the database will be in a consistent state. If an error occurs within a database LUW, all of the database changes since the beginning of the database LUW are reversed. This leaves the database in the state it was in before the transaction started.
The database changes that occur within a database LUW are not actually written to the database until after the database commit. Until this happens, you can use a database rollback to reverse the changes. In the SAP System, database commits and rollbacks can be triggered either implicitly or using explicit commands.
Implicit Database Commits
A work process can only execute a single database LUW. The consequence of this is that a work process must always end a database LUW when it finishes its work for a user or an external call. Work processes trigger an implicit database commit in the following situations:
·        When a dialog step is completed
Control changes from the work process back to the SAP GUI.
·        When a function module is called in another work process (RFC).
Control passes to the other work process.
·        When the called function module (RFC) in the other work process ends.
Control returns to the calling work process.
·        When a WAIT statement interrupts the work process.
Control passes to another work process.
·        Error dialogs (information, warning, or error messages) in dialog steps.
Control passes from the work process to the SAP GUI.
Explicit Database Commits
There are two ways to trigger an explicit database commit in your application programs:
·        Call the function module DB_COMMIT
The sole task of this function module is to start a database commit.
·        Use the ABAP statement COMMIT WORK
This statement starts a database commit, but also performs other tasks (refer to the keyword documentation for COMMIT WORK).
Implicit Database Rollbacks
The following cases lead to an implicit database rollback:
·        Runtime error in an application program
This occurs whenever an application program has to terminate because of an unforeseen situation (for example, trying to divide by zero).
·        Termination message
Termination messages are generated using the ABAP statement MESSAGE with the message type A or X. In certain cases (updates), they are also generated with message types I, W, and E. These messages end the current application program.
Explicit Database Rollbacks
You can trigger a database rollback explicitly using the ABAP statement ROLLBACK WORK. This statement starts a database rollback, but also performs other tasks (refer to the keyword documentation for ROLLBACK WORK).
From the above, we can draw up the following list of points at which database LUWs begin and end.
A Database LUW Begins
·        Each time a dialog step starts (when the dialog step is sent to the work process).
·        Whenever the previous database LUW ends in a database commit.
·        Whenever the previous database LUW ends in a database rollback.
A Database LUW Ends
·        Each time a database commit occurs. This writes all of the changes to the database.
·        Each time a database rollback occurs. This reverses all of the changes made during the LUW.
Database LUWs and Database Locks
As well as the database changes made within it, a database LUW also consists of database locks. The database system uses locks to ensure that two or more users cannot change the same data simultaneously, since this could lead to inconsistent data being written to the database. A database lock can only be active for the duration of a database LUW. They are automatically released when the database LUW ends. In order to program SAP LUWs, we need a lock mechanism within the R/3 System that allows us to create locks with a longer lifetime (refer to The SAP Locking Concept).
Reward Points if useful
Raghunath.S
9986076729

Wat is LUW

what is LUW?
I have gone through SAp help for the same but couldnt grasp the correct concept,Could you please explain in me in simple language understable by an average abaper

Hi,
Database LUW vs. SAP LUW
In the case of the database, an LUW is a sequence of data operations that cannot be divided up. The operations are either carried out in full or not at all. Database LUWs are modules that make up the database procedures for consistent data processing.
By way of contrast, an LUW for the SAP System is a business process, which cannot be divided up. The process is either executed in full or not at all. An SAP LUW usually must include several database LUWs (see graphic above), each of which can be terminated with a database COMMIT, which is generated automatically. Under normal circumstances, the SAP LUW contains a dialog part (which maps a business process), and the command for writing the data to the database (update part).
In each database LUW, data is written to the database to special update tables (and not to the application tables). Once the dialog part has been completed, all of the data in a database LUW is transferred into the application tables: the update request is then performed.
Have a look at below link.
[http://help.sap.com/saphelp_nw04/helpdata/en/41/7af4bfa79e11d1950f0000e82de14a/content.htm]
HTH,
Regards,
Dhruv Shah

Pls answer the following questions:

Hi friends,
Please let me know the answers to the following abap questions:
1. To link the loop to a table contro, we use the additon WITH CONTROL else this works as a stand-alone ___________________.
2. TCODE to check for the consistency of workflow for ALE/ED in INbound error processing?
3. what is the field to b used n the field catalog of an ALV report to hide the relevant column in the list?
4. what are the standard programs to transport transaction variants and screen variants?
5.__________________is triggered when all the data records of a node of the logical database have been read.
6. Expand and define EDIFACT?
7.What are the various print modes available in sap scripts?
8. TCODE to maintain transaction variants?
9. what s the tabale to find the Directory of Memory ID's?
10.Maximum number of Watchpoints and breakpoints in a program?
11.The ___________statement of the screen flow logic controls the data atransport fromt the Dynpro to the ABA program during the event PAI?
12.What is the standard program to check the consistency of partner profiles?
13. What is the table to find the change pointer status?
14. You can convert pooled tables to transpartent table with the _________________ of the techncal settings?
15.Messages available in SE91 TCODE are stored in which table?
16.Data records of tables having delivery class __ __ are not imported into the target system whereas data records of tables having delivery classes __ __ __ __ are imported into the target system.
17.Is it possible to debug Field exits?
18. In select....upto N rows statement, if N is zero then, ___________
19. The system field ______contains the total number of table control rows displayed on the screen.
20. Tcode to activate the change pointers for a particular message type?
21. is it possible to alter the width of the main window on each page?
22. what is the varialbe to be used in SAP scripts to find the total number of pagges of the print job?
23. Command to flush the database buffer
24. how to modify SAP standard tables?
25. what is the function module used with BAPI to commit?
26. what is the business object for purchase order?
27. What is cardinality
28. how to create a secondary index
29. define seconday index
30. how many secondary indexes can be created for cluster tables
31. how many main windows we can have in a script and smartforms? where is is mandatory?
32. what is LUW, different types of LUW.
33.What are version management functions
34.how many push buttons can u place on selection-screen application tool bar and what is the default function code for that buttons
35. what are the views that can not b used to create new views
36. how can u find out whether a record is successfully updated or not
37.how to find if a logical databse exists for your program requirements
38.what is a control table
39.how customers can search the SAP information databse and find solutions for errors and problems with R/3 systems?
40.what is DYNPRO? what are its components?
41.using which program we can copy table across clients in scripts
42.how to set Tablespaces and extent sizes
43.what is the maximum number of structures that can b included in a table
44. what is a match code
45. what is the maximum number of match code id's that can b defined for one Match code object
46. what specific statemnets do you use to write a drill down report
47.you can link a search help to a preameter using syntax __________________________.
48. how to find a standard program in SAP?

Hi friends,
Please let me know the answers to the following abap questions:
1. To link the loop to a table contro, we use the additon WITH CONTROL else this works as a stand-alone ___________________.
2. TCODE to check for the consistency of workflow for ALE/ED in INbound error processing?
3. what is the field to b used n the field catalog of an ALV report to hide the relevant column in the list?
4. what are the standard programs to transport transaction variants and screen variants?
5.__________________is triggered when all the data records of a node of the logical database have been read.
6. Expand and define EDIFACT?
7.What are the various print modes available in sap scripts?
8. TCODE to maintain transaction variants?
9. what s the tabale to find the Directory of Memory ID's?
10.Maximum number of Watchpoints and breakpoints in a program?
11.The ___________statement of the screen flow logic controls the data atransport fromt the Dynpro to the ABA program during the event PAI?
12.What is the standard program to check the consistency of partner profiles?
13. What is the table to find the change pointer status?
14. You can convert pooled tables to transpartent table with the _________________ of the techncal settings?
15.Messages available in SE91 TCODE are stored in which table?
16.Data records of tables having delivery class __ __ are not imported into the target system whereas data records of tables having delivery classes __ __ __ __ are imported into the target system.
17.Is it possible to debug Field exits?
18. In select....upto N rows statement, if N is zero then, ___________
19. The system field ______contains the total number of table control rows displayed on the screen.
20. Tcode to activate the change pointers for a particular message type?
21. is it possible to alter the width of the main window on each page?
22. what is the varialbe to be used in SAP scripts to find the total number of pagges of the print job?
23. Command to flush the database buffer
24. how to modify SAP standard tables?
25. what is the function module used with BAPI to commit?
26. what is the business object for purchase order?
27. What is cardinality
28. how to create a secondary index
29. define seconday index
30. how many secondary indexes can be created for cluster tables
31. how many main windows we can have in a script and smartforms? where is is mandatory?
32. what is LUW, different types of LUW.
33.What are version management functions
34.how many push buttons can u place on selection-screen application tool bar and what is the default function code for that buttons
35. what are the views that can not b used to create new views
36. how can u find out whether a record is successfully updated or not
37.how to find if a logical databse exists for your program requirements
38.what is a control table
39.how customers can search the SAP information databse and find solutions for errors and problems with R/3 systems?
40.what is DYNPRO? what are its components?
41.using which program we can copy table across clients in scripts
42.how to set Tablespaces and extent sizes
43.what is the maximum number of structures that can b included in a table
44. what is a match code
45. what is the maximum number of match code id's that can b defined for one Match code object
46. what specific statemnets do you use to write a drill down report
47.you can link a search help to a preameter using syntax __________________________.
48. how to find a standard program in SAP?

Please answer these qs its urgent...

1.To link the loop to a table control, we use the addition WITH CONTROL else this works as a stand-alone ____________ _______.
2. TCODE to check for the consistency of workflow for ALE/ED in INbound error processing?
3. what is the field to b used n the field catalog of an ALV report to hide the relevant column in the list?
4. what are the standard programs to transport transaction variants and screen variants?
5.__________ ________is triggered when all the data records of a node of the logical database have been read.
6. Expand and define EDIFACT?
7.What are the various print modes available in sap scripts?
8. TCODE to maintain transaction variants?
9. what s the table to find the Directory of Memory ID's?
10.Maximum number of Watchpoints and breakpoints in a program?
11.The ___________statemen t of the screen flow logic controls the data transport from the Dynpro to the ABAP program during the event PAI?
12.What is the standard program to check the consistency of partner profiles?
13. What is the table to find the change pointer status?
14. You can convert pooled tables to transparent table with the ____________ _____ of the technical settings?
15.Messages available in SE91 TCODE are stored in which table?
16.Data records of tables having delivery class __ __ are not imported into the target system whereas data records of tables having delivery classes __ __ __ __ are imported into the target system.
17.Is it possible to debug Field exits?
18. In select....upto N rows statement, if N is zero then, ___________
19. The system field ______contains the total number of table control rows displayed on the screen.
20. Tcode to activate the change pointers for a particular message type?
21. is it possible to alter the width of the main window on each page?
22. what is the varialbe to be used in SAP scripts to find the total number of pagges of the print job?
23. Command to flush the database buffer
24. how to modify SAP standard tables?
25. what is the function module used with BAPI to commit?
26. what is the business object for purchase order?
27. What is cardinality
28. how to create a secondary index
29. define seconday index
30. how many secondary indexes can be created for cluster tables
31. how many main windows we can have in a script and smartforms? where is is mandatory?
32. what is LUW, different types of LUW.
33.What are version management functions
34.how many push buttons can u place on selection-screen application tool bar and what is the default function code for that buttons
35. what are the views that can not b used to create new views
36. how can u find out whether a record is successfully updated or not
37.how to find if a logical databse exists for your program requirements
38.what is a control table
39.how customers can search the SAP information databse and find solutions for errors and problems with R/3 systems?
40.what is DYNPRO? what are its components?
41.using which program we can copy table across clients in scripts
42.how to set Tablespaces and extent sizes
43.what is the maximum number of structures that can b included in a table
44. what is a match code
45. what is the maximum number of match code id's that can b defined for one Match code object
46. what specific statements do you use to write a drill down report
47.you can link a search help to a parameter using syntax ____________ _________ _____.
48. how to find a standard program in SAP?
Regards
Pallav

1.To link the loop to a table control, we use the addition WITH CONTROL else this works as a stand-alone ____________ _______.
2. TCODE to check for the consistency of workflow for ALE/ED in INbound error processing?
3. what is the field to b used n the field catalog of an ALV report to hide the relevant column in the list?
4. what are the standard programs to transport transaction variants and screen variants?
5.__________ ________is triggered when all the data records of a node of the logical database have been read.
6. Expand and define EDIFACT?
7.What are the various print modes available in sap scripts?
8. TCODE to maintain transaction variants?
9. what s the table to find the Directory of Memory ID's?
10.Maximum number of Watchpoints and breakpoints in a program?
11.The ___________statemen t of the screen flow logic controls the data transport from the Dynpro to the ABAP program during the event PAI?
12.What is the standard program to check the consistency of partner profiles?
13. What is the table to find the change pointer status?
14. You can convert pooled tables to transparent table with the ____________ _____ of the technical settings?
15.Messages available in SE91 TCODE are stored in which table?
16.Data records of tables having delivery class __ __ are not imported into the target system whereas data records of tables having delivery classes __ __ __ __ are imported into the target system.
17.Is it possible to debug Field exits?
18. In select....upto N rows statement, if N is zero then, ___________
19. The system field ______contains the total number of table control rows displayed on the screen.
20. Tcode to activate the change pointers for a particular message type?
21. is it possible to alter the width of the main window on each page?
22. what is the varialbe to be used in SAP scripts to find the total number of pagges of the print job?
23. Command to flush the database buffer
24. how to modify SAP standard tables?
25. what is the function module used with BAPI to commit?
26. what is the business object for purchase order?
27. What is cardinality
28. how to create a secondary index
29. define seconday index
30. how many secondary indexes can be created for cluster tables
31. how many main windows we can have in a script and smartforms? where is is mandatory?
32. what is LUW, different types of LUW.
33.What are version management functions
34.how many push buttons can u place on selection-screen application tool bar and what is the default function code for that buttons
35. what are the views that can not b used to create new views
36. how can u find out whether a record is successfully updated or not
37.how to find if a logical databse exists for your program requirements
38.what is a control table
39.how customers can search the SAP information databse and find solutions for errors and problems with R/3 systems?
40.what is DYNPRO? what are its components?
41.using which program we can copy table across clients in scripts
42.how to set Tablespaces and extent sizes
43.what is the maximum number of structures that can b included in a table
44. what is a match code
45. what is the maximum number of match code id's that can b defined for one Match code object
46. what specific statements do you use to write a drill down report
47.you can link a search help to a parameter using syntax ____________ _________ _____.
48. how to find a standard program in SAP?
Regards
Pallav

What is LUW?

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