ABAP - Sort in loop or read w/o binary search

[Former Member]

Hi Expert,

I need your advice on using a SORT statement inside a loop or using read without Binary search inside loop.

i.e. Loop IT_TAB. SORT IT_TAB2 (IT_TAB2 table is populated with data inside same loop) . Read IT_TAB2 using Binary search. Endloop,

OR Loop IT_TAB. Read IT_TAB2 without Binary search. Endloop.

Which one is better?

Regards,

Raj

[Former Member]

Hi Expert,

I need your advice on using a SORT statement inside a loop or using read without Binary search inside loop.

i.e. Loop IT_TAB. SORT IT_TAB2 (IT_TAB2 table is populated with data inside same loop) . Read IT_TAB2 using Binary search. Endloop,

OR Loop IT_TAB. Read IT_TAB2 without Binary search. Endloop.

Which one is better?

Regards,

Raj

[harald_lesche-holzbecher]

You say "IT_TAB2 table is populated with data inside same loop"

So I suggest 3rd approach:

- sort IT_TAB2 prior to Loop IT_TAB (in case there are entries already)

- within Loop IT_TAB add new entries to IT_TAB2 so it is sorted

- you may now Read IT_TAB2 with Binary search without necessity to sort again

[Tomas_Buryanek]

Do not use SORT + BINARY SEARCH method!

There are much better options for fast internal table access / processing. Try SORTED or HASHED tables or at least use secondary table keys (SORTED or HASH).

[Sandra_Rossi]

If I understand your question well, IT_TAB2 is populated inside the loop in both cases, and you ask which of solution 1 (SORT + READ binary search) or solution 2 (READ without binary search) is the best.

First of all, the question is the same if there's no loop at all.

Let's calculate the "order":

Solution 1: SORT will read ALL the lines of a table (N)

Solution 2: READ without binary search will statistically tend to read half the lines if values are distributed equally and the searched value is random (N/2).

Answer: solution 2.

PS: I didn't even count the additional time needed for solution 1, to rebuild the index of lines, and to do a binary search.

[Sandra_Rossi]

Is IT_TAB2 cleared & populated in each loop, or some lines are just added or removed?

[s1252]

If IT_TAB2 is type of a sorted table, we don’t have to sort it again and we can use binary search.

[matt]

Don't use BINARY SEARCH. Use a sorted or hashed table. See Tomas Buryanek's answer below.

Binary search should not appear in modern programs. It isn't needed.

[matt]

s1252 If it's a SORTED table, then you don't need the addition BINARY SEARCH. It will be done automatically (assuming you're using the table key).