DELETE WHERE sample case that i would like to share with you

Question

Hi,
analyzing a program the other day i got the following hit list in SE30 as TOP 2 and TOP 3 of the most
expensive calls sorted by net time descending.
  Number        Gross =         Net Gross (%) Net (%) Call 
   11.975  23.651.879    15.612.054   12,0    7,9  Loop at IT_126570  
8.698.597   8.039.825  =  8.039.825    4,1    4,1  Append IT_126574
source code excerpt:
REFRESH it_dict[].
it_dict[] = ist_dict[].
DELETE it_dict WHERE charactname  NE pv_charactname
                   AND   language_int = pv_language_int.
it_dict and ist_dict are both sorted tables with a non-unique key with charactname language_int tabix value_char.
Note: The DELETE WHERE is intarnally processed as a LOOP WHERE which APPENDS the the lines
to be deleted to an internal system table which afterwards is used in a system call that does the
delete (not visible). Since ST12 (which i use normally) combines the LOOP and the APPEND to a
single line which shows DELETE as the call i used SE30 here to show all the details.
Now what?
(How) can we optimize it?
How much time can we save?
I will follow up with more details later since there are some interesting things to show i think.
Kind regards,
Hermann

Answer 1

More tests while I haven't deleted the program...
If I keep the first characteristic (and not the one in the middle), the winner is the same (but the 1st case is now slower than the 3rd):
(I had to make small adjustments to correctly use FROM and TO when the characteristic is not in the middle)
Copy + Delete                     5.381  (      2.396  lines )
Loop + Insert                     7.888  (      2.396  lines )
Loop + Append                     2.994  (      2.396  lines )
Copy + Delete From To               509  (      2.396  lines )
Loop + Append From To             1.041  (      2.396  lines )
Loop + Insert From To               691  (      2.396  lines )
Determine From To                   400
If I keep the last one, then option 6 is now clearly the best:
Start (     10.553  lines )                                                                               
Copy + Delete                     5.582  (      1.942  lines )
Loop + Insert                     6.573  (      1.942  lines )
Loop + Append                     3.361  (      1.942  lines )
Copy + Delete From To             1.581  (      1.942  lines )
Loop + Append From To               922  (      1.942  lines )
Loop + Insert From To               566  (      1.942  lines )
Determine From To                   301
Finally, if the characteristic we are looking for is actually not there, then:
Start (     10.553  lines )                                                                               
Copy + Delete                     6.280  (          0  lines )     
Loop + Insert                        14  (          0  lines )     
Loop + Append                         4  (          0  lines )     
Copy + Delete From To               173  (          0  lines )     
Loop + Append From To                10  (          0  lines )     
Loop + Insert From To                 8  (          0  lines )     
Determine From To                     4
Well, sorry for continuing to post on your answered thread. We are ready for the next one..