Regarding hash table and performance tuning...

Hi,

I have one more question.

1) When do we use hash table in ABAP? what is the advantage of using it?

2) Whenever we want tp performance tune a given report what is the procedure to do it ? Is it just like first run run-time analysis and SQL trace and then see various issues involved like fewer database access and other stuff?

Thanks...

Regards,

Tushar.