About sorting in the SORT instruction...

[Former Member]

Hello,

I have searched if someone posted this question before, but I couldn't find it:

How does the SORT instruction actually sort the table that is passed? Which is the sorting algorithm used?

And: Why is it an instruction?

Just curious...

Thanks a lot!,

Eloi

[Former Member]

Hello,

I have searched if someone posted this question before, but I couldn't find it:

How does the SORT instruction actually sort the table that is passed? Which is the sorting algorithm used?

And: Why is it an instruction?

Just curious...

Thanks a lot!,

Eloi

[Former Member]

hi,

for sorting we follow the linear search,binary search and hash based search algorithms. These algorithms are depend on type of internal table.

[Former Member]

The documentation does not mention it but as far as I know the SORT command is implemented using quick sort. This also explains why the sort is not stable.

Since ABAP is a 4th generation language, it would be pretty weird to not have a SORT command. And an implementation in the kernel will always be faster than anything built in ABAP. Why you need it in your program is a whole different story, I see it misused a lot where the sorting could have been done during SELECT or the sort is only done to remove duplicates that could have been avoided with some smarter SELECTs.

[Former Member]

SORT command allows to use [STABLE] clause therefore it has to change, in that case, its sorting method.

It's interesting what you said about sorting misuse. So far I have read through the forums to be a good practice to assign the effort of sorting to the application server rather than the database one. No?

Thanks for your reply Gerrit.

[Former Member]

As per me Sorting algorithm varies based on system to system and different parameters.

E.G :

1. Application server type : Linux/Unix/Windows/Sybase/Solaris.

2. System type : 32 bit/64 bit

3. Unicode system : Yes/No

4. Type of internal table : Hashed/Sorted/Standard

Check this note 193529 also

193529 - Sort as of 4.5A/EXSORT_NOT_ENOUGH_MEMORY

They use a term called "Disk sort" which is more closer to Merge Sort we have in C, when the data becomes higher than a certain limit and in some cases they use quick sort.

Also I agree in a typical 3 tier environment it is recommended to do the sorting in application server rather in database level but is about to change with SAP HANA.

R

[Former Member]

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