Description: Meshes are special structures composed of internal tables that can be connected through associations. These associations are accessed using mesh paths within specific expressions and statements.

• A Mesh separates the definition of relationships from their usage. For example, if an item record includes a “parent_key” field that references its corresponding header record, this relationship is defined only once within the Mesh.
• Without a Mesh, the same logic must be repeated in every LOOP that processes items by header, and in every READ statement that retrieves a header from an item. If the data model changes, ideally only the Mesh definition needs to be updated—eliminating the need to modify all affected LOOPs and READ statements.
• Mesh is defined like a structure.

Syntax:

TYPES BEGIN OF MESH 
  ... 
  TYPES snode ... ASSOCIATION _assoc 
                  TO tnode ON tcomp1 = scomp1 [AND ...]. 
  ... 
TYPES END OF MESH

Example:

*&---------------------------------------------------------------------*
*& Report ZMESHRPT
*&---------------------------------------------------------------------*
*& Purpose: Learn how to use Meshes
*& Author : Sangeeta Singh
*&---------------------------------------------------------------------*

REPORT zmeshrpt.

"Declare Meshes type
TYPES: BEGIN OF ty_vbak,
         vbeln TYPE vbeln,
         erdat TYPE erdat,
         auart TYPE auart,
       END OF ty_vbak,
       BEGIN OF ty_vbap,
         vbeln TYPE vbeln,
         posnr TYPE posnr,
         matnr TYPE matnr,
         arktx TYPE arktx,
       END OF ty_vbap,
       tt_vbak TYPE STANDARD TABLE OF ty_vbak WITH KEY vbeln,
       tt_vbap TYPE STANDARD TABLE OF ty_vbap WITH KEY vbeln posnr,
       BEGIN OF MESH ty_po,
         vbak TYPE tt_vbak ASSOCIATION _to_item TO vbap
                           ON vbeln = vbeln ,
         vbap TYPE tt_vbap,
       END OF MESH ty_po.

DATA: ls_po TYPE ty_po.

"Fill data in the created mesh
SELECT vbeln erdat auart
       FROM vbak INTO TABLE ls_po-vbak UP TO 20 ROWS.
IF sy-subrc = 0.
  SELECT vbeln posnr matnr arktx
         FROM vbap
         INTO TABLE ls_po-vbap
         FOR ALL ENTRIES IN ls_po-vbak
         WHERE vbeln = ls_po-vbak-vbeln.
  IF sy-subrc <> 0.
    MESSAGE 'No Data Found' TYPE 'S' DISPLAY LIKE 'E'.
  ENDIF.
ENDIF.

"Loop on meshes
LOOP AT ls_po-vbak ASSIGNING FIELD-SYMBOL(<lfs_vbak>).
  DATA(ls_item) = ls_po-vbak\_to_item[ ls_po-vbak[ vbeln = <lfs_vbak>-vbeln ] ].
  "As you can see we don't need additonal loop here
  " we can fetch data based on association
  WRITE: / ls_item-vbeln, ls_item-posnr,  ls_item-matnr,ls_item-arktx.
ENDLOOP.

Output:

As you can see Meshes is a deep structure which is holding VBAK and VBAP data.

Conclusion:

Meshes in ABAP on HANA simplify relationship handling between internal tables. They reduce code duplication, improve clarity, and make maintenance easier by centralizing relationship logic through associations and mesh paths.

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