Report Performance - timeout short dump

Question

Hello Experts,
i am trying to improve the performace of a report that was developed long time ago.
Issues i found:
1. The report has many select...Endselect combinations, and selects inside the loop statements.
2. Most of the selects have the addition 'into corresponding fields of' for selecting a few fields, without  the table addition.
3.  Also few selects have the 'select * from'  syntax.
data: begin of itab occurs 0,
          f1,
          f2
          f3.....
          fn,          
        end of itab.
Ex: loop at itab.
         select f1 f2 f3 from table1
               into corresponding fields of itab1.
           collect itab1.
         endselect.
          select f4 f5 from table2
              into corresponding fields of itab2.
           endselect.
      endloop.
All this leeds to performace issues.
i have checked ST05, and i have got the details of the error.
My question is which one of the reasons i mentioned above are a major factor in delaying the report performance?
Which one of the above should i conetrate first to get the long runtime down? My goal is to keep my changes to the minimum and improve the performance. Please advise.

Answer 1

> My question is which one of the reasons i mentioned above are a major factor in delaying the report
> performance?
Don't ask people for guesses, if you can see the facts!
Run the SQL Trace several times, and use go to 'Trace List' -> 'Summarize Trace by SQL Statement'
=> Shows you total DB time and time per statement (all executions), the problems are on top of the list.
Check ABAP, detail, and explain!
Read more here:
/people/siegfried.boes/blog/2007/09/05/the-sql-trace-st05-150-quick-and-easy
Siegfried