topic Re: Performance issue in Application Development and Automation Discussions

Performance issue

Former Member — Thu, 18 Aug 2005 12:36:27 GMT

Hello All,

Can anyone tell me which is alternate option for select query <b>For all entries in [itab]</b> where ...

Regards,

Dilip

Re: Performance issue

RichHeilman — Thu, 18 Aug 2005 12:43:13 GMT

Yes, you can loop at the first internal table and do a select statement in the loop.



Loop at itab.

* Do Select here and whatever else you
* need to do with the data.

endloop.

Regards,

Rich Heilman

Re: Performance issue

andreas_mann3 — Thu, 18 Aug 2005 12:43:49 GMT

Hi,

try :

Loop at itab.

select (single) a1 a2 .. from dbtab

where key1 = itab-f1

and key2 = itab-f2

endloop.

Andreas

Re: Performance issue

Vinod_Chandran — Thu, 18 Aug 2005 12:54:20 GMT

Hi Dilip,

Do you have a performance issue when using For all entries? Please keep in mind that you must check whether the internal table contains some entries. If it is not, then it will select all the records from the table.

For example.

IF NOT ITAB[] IS INITIAL.

SELECT....FROM DBTAB

FOR ALL ENTRIES IN ITAB

WHERE....

ENDIF.

Re: Performance issue

Former Member — Thu, 18 Aug 2005 12:57:40 GMT

Hi, the most scenario for me to use 'For all entrie' is as following:

If several table combine in a join select, maybe it will be poor on performance. So we need to split the join select into several single select. Then after first select, we can prepare the result in a internal table, and use it in another select as 'For all entries in [itab]'.

E.G. as following:

original:

select *

into ....

from mseg

inner join in mkpf .....

where mkpf_{MBLNR = mseg}MBLNR.

it is slow, so we change it

select MBLNR

into table itab

from mkpf.

select *

into ....

from mseg

for all entries in itab

where MBLNR = itab~MBLNR.

Another fact is that the where use 'For all entries in', if the itab is very big, the whole select statement will be compiled and explained to be many pieces of select statements, and sent to DB layer.

So if the 'For all entries in' itab is too large, the select will be slow too.

Hope it will be helpful.

Thanks a lot

Re: Performance issue

Former Member — Thu, 18 Aug 2005 13:10:20 GMT

Hi ,

Follow the following steps before using FOR ALL ENTRIES -

1) Check internal table that it is not empty .

2) If it have entries then SORT the table .

3) Delete duplicate entries from the table .

4) Use any key field in WHERE clouse.

it may help you.

Regards

Message was edited by: Nandkishor Heda