Do Not Mutate the Internal Table Currently Being Looped

WarningPerformance & Database#EC LOOP_MODIFYRemote Enabled

Overview

Avoid mutating or sorting tables inside loops.

ATC Finding Messages:

• Do not add, delete, sort, collect, or clear rows from the table currently being looped
• Avoid sorting internal tables inside loops to prevent severe performance degradation

Rationale

Appending, inserting, modifying, or deleting rows of the table being looped can invalidate the loop cursor. The result may be skipped rows, duplicate processing, or an endless loop. Iterate over a snapshot or collect changes in a separate table and apply them after the loop.

Non-Compliant

LOOP AT lt_orders INTO ls_order.
  INSERT ls_order INTO lt_orders.
ENDLOOP.

Compliant

LOOP AT lt_orders INTO ls_order.
  INSERT ls_order INTO lt_processed_orders.
ENDLOOP.

Configuration & Thresholds

This check can be fine-tuned directly in the ATC Check Variant Editor (CHKV) in Eclipse ADT:

Parameter Name	Data Type	Default Value
CHECK_APPEND	Boolean	true
CHECK_INSERT	Boolean	true
CHECK_MODIFY	Boolean	true
CHECK_DELETE	Boolean	true
CHECK_CLEAR	Boolean	true
CHECK_SORT	Boolean	true
CHECK_SORT_ANY	Boolean	true
CHECK_COLLECT	Boolean	true

Suppression

To suppress findings for this rule, append the pseudo-comment to the statement:

" Standard pseudo-comment:
... "#EC LOOP_MODIFY

" SAP CI_ prefix format:
... "#EC CI_LOOP_MODIFY

Technical Details

• Native ATC Class: ZCL_SKYLINT_NO_MOD_LOOP_TAB
• Implementation File: zcl_skylint_no_mod_loop_tab.clas.abap