topic Avoiding nested Loops in Application Development and Automation Discussions

Avoiding nested Loops

Former Member — Wed, 04 Mar 2015 06:00:49 GMT

Hi ,

My loop condition is taking much time for execution. The tables used are BKPF & BSEG. Please find the condition given below.

LOOP AT T_BKPF WHERE SUPER = T_SUPER-NAME.

IF USNAM NE T_BKPF-USNAM.

MOVE T_BKPF-UNAM TO H-USNAM.

NEW-PAGE.

ENDIF.

PERFORM OUT.

LOOP AT T_BSEG WHERE BELNR = T_BKPF-BELNR

AND GJAHR = T_BKPF-GJAHE.

CASE T_BSEG-KOART.

WHEN 'L'.

PERFOM....

...................

ENDCASE.

ENDLOOP.

Please help me to over come this issue.

Re: Avoiding nested Loops

rajkumarnarasimman — Wed, 04 Mar 2015 06:11:46 GMT

Hi Barani,

Can you share the full code.

Regards

Rajkumar Narasimman

Re: Avoiding nested Loops

Former Member — Wed, 04 Mar 2015 06:16:19 GMT

use field-symbols, do not use internal tables with header lines. That should be your 1st step.

Re: Avoiding nested Loops

vinodkumar_thangavel — Wed, 04 Mar 2015 07:17:50 GMT

Hi Barani,

1) Sort the Internal table before using where condition in loop,

2) Try to avoid using perform inside loop.

Regards,

Vinodkumar.

Re: Avoiding nested Loops

Former Member — Wed, 04 Mar 2015 07:57:16 GMT

Hi Barani,

SORT T_BSEG BY belnr gjahr.

LOOP AT T_BKPF WHERE SUPER = T_SUPER-NAME.

IF USNAM NE T_BKPF-USNAM.

MOVE T_BKPF-UNAM TO H-USNAM.

NEW-PAGE.

ENDIF.

PERFORM OUT.

READ TABLE T_BSEG WITH KEY BELNR = T_BKPF-BELNR GJAHR = T_BKPF-GJAHE

BINARY SEARCH.

IF SY-SUBRC EQ 0.

LOOP AT T_BSEG FROM INDEX sy-tabix.

IF T_BSEG-BELNR EQ T_BKPF-BELNR AND T_BSEG-GJAHR = T_BKPF-GJAHE.

CASE T_BSEG-KOART.

WHEN 'L'.

PERFOM....

...................

ENDCASE.

ELSE.

EXIT.

ENDIF.

ENDLOOP.

regards,

Archer

Re: Avoiding nested Loops

franz_reitmayer2 — Wed, 04 Mar 2015 08:05:31 GMT

Hi,

Really hard to say without the "surrounding code". As far as I can see you've a nested loop because you're performing a join at the abap side. In general I'd delegate that to the database, but for your case it would be interessting how and why t_bkpf and t_bseg are filled. As BESG is a cluster table it's also a special case.

But to answer the question how to avoid nested loops: I'd recommend to join at database.

Regards,

Franz

Re: Avoiding nested Loops

rajkumarnarasimman — Wed, 04 Mar 2015 08:10:10 GMT

Hi Barani,

There are two concerns here.

Using Nested loop which decreases the performance. Instead of that we can use parallel cursor method, which fetches the data using index method.
1. ABAP Code for Parallel Cursor - Loop Processing - Code Gallery - SCN Wiki
Second one is instead of fetching the data from BSEG cluster table, we can fetch from some index table

INDEX TABLES:

BSID- Accounting: Secondary Index for Customers (Open Items)

BSAD- Accounting: Secondary Index for Customers (Cleared Items)

BSIK- Accounting: Secondary Index for Vendors (Open Items)

BSAK- Accounting: Secondary Index for Vendors (Cleared Items)

BSIS- Accounting: Secondary Index for G/L Accounts (Open Items)

BSAS- Accounting: Secondary Index for G/L Accounts (Cleared Item)

Please find the link below.

How SAP addressed the performance issues with cluster table BSEG? - ABAP Development - SCN Wiki

Regards

Rajkumar Narasimman

Re: Avoiding nested Loops

former_member37854 — Wed, 04 Mar 2015 08:57:05 GMT

Hi Barani,

If nested loop cannot be able to avoid, please try with below sample if it helps.

it's a litter bit difference with the code from Dengyong Zhang.

T_BKPF_BACKUP = T_BKPF.

* Remove all unneeded entry to improve performance

DELETE T_BKPF_BACKUP WHERE SUPER <> T_SUPER-NAME.

SORT: T_BKPF_BACKUP BY BUKRS BELNR GJAHR,

T_BSEG BY BUKRS BELNR GJAHR.

lv_tabix = 1. "Set the starting index 1

LOOP AT T_BKPF_BACKUP.

IF USNAM NE T_BKPF-USNAM.

MOVE T_BKPF-UNAM TO H-USNAM.

NEW-PAGE.

ENDIF.

PERFORM OUT.

LOOP AT T_BSEG FROM lv_tabix.

* Save index & Exit the loop, if the keys are not same

IF T_BKPF_BACKUP-BUKRS <> T_BSEG-BUKRS

OR T_BKPF_BACKUP-BELNR <> T_BSEG-BELNR

OR T_BKPF_BACKUP-GJAHR <> T_BSEG-GJAHR.

lv_tabix = sy-tabix.

EXIT.

ENDIF.

CASE T_BSEG-KOART.

WHEN 'L'.

PERFOM....

...................

ENDCASE.

ENDLOOP.