/sap-abap

SAP Logical Unit of Work (LUW) - Complete Reference

Source: https://github.com/SAP-samples/abap-cheat-sheets/blob/main/17_SAP_LUW.md

Overview

SAP LUW ensures transactional consistency through all-or-nothing commits: either all changes commit together or all rollback.

COMMIT and ROLLBACK

COMMIT WORK

COMMIT WORK.              " Asynchronous - returns immediately
COMMIT WORK AND WAIT.     " Synchronous - waits for completion

Effects:

• Closes current SAP LUW, opens new one
• Commits all change requests
• Processes registered update function modules
• Triggers database commit

ROLLBACK WORK

ROLLBACK WORK.

Effects:

• Closes current SAP LUW, opens new one
• Undoes all changes within current SAP LUW
• Removes previous registrations
• Triggers database rollback

Update Function Modules

Calling Update Functions

" Asynchronous (default)
CALL FUNCTION 'Z_UPDATE_FUNC' IN UPDATE TASK
  EXPORTING values = data.

COMMIT WORK.  " Returns immediately

" Synchronous
CALL FUNCTION 'Z_UPDATE_FUNC' IN UPDATE TASK
  EXPORTING values = data.

COMMIT WORK AND WAIT.  " Waits for completion

" Local update
SET UPDATE TASK LOCAL.

CALL FUNCTION 'Z_UPDATE_FUNC' IN UPDATE TASK
  EXPORTING values = data.

COMMIT WORK.  " Executes immediately in current work process

Update Function Implementation

FUNCTION z_update_func
  IMPORTING
    VALUE(values) TYPE some_dbtab.

  MODIFY some_dbtab FROM @values.

ENDFUNCTION.

Background RFC (bgRFC)

CALL FUNCTION 'Z_REMOTE_FUNC' IN BACKGROUND UNIT
  EXPORTING param1 = value1.

Enables asynchronous execution in same or different ABAP systems.

Subroutines (Deprecated)

" Register for commit
PERFORM some_subroutine ON COMMIT.

" Register for rollback
PERFORM some_subroutine ON ROLLBACK.

" Data transfer via ABAP memory
EXPORT data_var TO MEMORY ID 'KEY'.
IMPORT data_var FROM MEMORY ID 'KEY'.

Implicit Database Commits

Triggered automatically by:

• Dialog step completion (dynpro PAI/PBO)
• Synchronous/asynchronous RFC calls
• HTTP/HTTPS/SMTP communication
• WAIT statements
• Sending messages (error, information, warning)

ABAP Cloud Behavior

" Both behave identically in ABAP Cloud
COMMIT WORK.
COMMIT WORK AND WAIT.

In ABAP Cloud:

• Local updates always enforced implicitly
• Updates occur in same work process
• Always synchronous

RAP Integration

" RAP-specific commit
COMMIT ENTITIES.        " Implicitly triggers COMMIT WORK

" RAP-specific rollback
ROLLBACK ENTITIES.      " Resets all changes

Controlled SAP LUW

Enhanced transactional phase management:

" Activate modify phase
cl_abap_tx=>modify( ).

" Database modifications NOT allowed here
" Would throw BEHAVIOR_ILLEGAL_STMT_IN_CALL

" Activate save phase
cl_abap_tx=>save( ).

" Database modifications allowed here
MODIFY zdemo_table FROM TABLE @itab.

Transactional Phases

Lock Objects

" Enqueue (lock)
CALL FUNCTION 'ENQUEUE_EZLOCK'
  EXPORTING
    mode_table = 'E'
    key = value
  EXCEPTIONS
    foreign_lock = 1.

" Dequeue (unlock)
CALL FUNCTION 'DEQUEUE_EZLOCK'
  EXPORTING
    mode_table = 'E'
    key = value.

Best Practices

1. Use COMMIT WORK AND WAIT when immediate confirmation needed
2. Avoid implicit commits in transaction-critical code
3. Use RAP for modern transactional scenarios
4. Bundle modifications for consistency
5. Handle locks appropriately
6. Test rollback scenarios thoroughly