Memory and performance when copying a sorted table to a standard table

Question

Hello,
As you all probably know, it's not possible to use a sorted table as a tables parameter of a function module, but sometimes you want to use a sorted table in your function module for performance reasons, and at the end of the function module, you just copy it to a standard table to return to the calling program.
The problem with this is that at that moment, the contents of the table is in memory twice, which could result in the well known STORAGE_PARAMETERS_WRONG_SET runtime exception.                                                                               
I've been looking for ways to do this without using an excessive amount of memory and still being performant.  I tried four methods, all have their advantages and disadvantages, so I was hoping someone here could help me come up with the best way to do this.  Both memory and performance are an issue. 
Requirements :
- Memory usage must be as low as possible
- Performance must be as high as possible
- Method must work on all SAP versions from 4.6c and up
So far I have tried 3 methods.
I included a test report to this message, the output of this on my dev system is :
Test report for memory usage of copying tables    
table1[] = table2[]                                        
Memory :    192,751  Kb                                    
Runtime:    436,842            
Loop using workarea (with delete from original table)      
Memory :    196,797  Kb                                    
Runtime:  1,312,839        
Loop using field symbol (with delete from original table)  
Memory :    196,766  Kb                                    
Runtime:  1,295,009                                                                               
The code of the program :
I had some problems pasting the code here, so it can be found at [http://pastebin.com/f5e2848b5|http://pastebin.com/f5e2848b5]
Thanks in advance for the help.
Edited by: Dries Horions on Jun 19, 2009 1:23 PM
Edited by: Dries Horions on Jun 19, 2009 1:39 PM
Edited by: Dries Horions on Jun 19, 2009 1:40 PM
Edited by: Dries Horions on Jun 19, 2009 1:40 PM

Answer 1

I've had another idea:
Create a RFC function like this (replace SOLI_TAB with your table types):
FUNCTION Z_COPY_TABLE .
*"*"Lokale Schnittstelle:
*"  IMPORTING
*"     VALUE(IT_IN) TYPE  SOLI_TAB
*"  EXPORTING
*"     VALUE(ET_OUT) TYPE  SOLI_TAB
et_out[] = it_in[].
ENDFUNCTION.
and then try something like this in your program:
DATA: gd_copy_done TYPE c LENGTH 1.
DATA: gt_one TYPE soli_tab.
DATA: gt_two TYPE soli_tab.
PERFORM move_tables.
FORM move_tables.
  CLEAR gd_copy_done.
  CALL FUNCTION 'Z_COPY_TABLE'
    STARTING NEW TASK 'ztest'
    PERFORMING copy_done ON END OF TASK
    EXPORTING
      it_in = gt_one[].
  CLEAR gt_one[].
  WAIT UNTIL gd_copy_done IS NOT INITIAL.
ENDFORM.
FORM copy_done USING ld_task TYPE clike.
  RECEIVE RESULTS FROM FUNCTION 'Z_COPY_TABLE'
   IMPORTING
     et_out        = gt_two[].
  gd_copy_done = 'X'.
ENDFORM.
Maybe this is a little bit faster than the Memory-Export?
Edited by: Carsten Grafflage on Jul 20, 2009 11:06 AM