Hashed table is useful when your have to work with very big internal table
and to read it with
"READ TABLE WITH KEY ..."
The time access is constant !
Definition of a Hashed Table:
"Defines the table as one that is managed with an internal hash procedure. You
can imagine a hashed table as a set, whose elements you can address using their
unique key. Unlike standard and sorted tables, you cannot access hash tables
using an index. All entries in the table must have a unique key.
Access time using the key is constant, regardless of
the number of table entries.
You can only access a hashed table using the generic key operations or other
generic operations (SORT, LOOP, and so on). Explicit or implicit index
operations (such as LOOP ... FROM to INSERT itab within a LOOP) are not
allowed."
As long as your records has unique key(s), using hash table will give you a
huge performance gain when dealing with large dataset. assuming in your case,
10000 record , and if the key is unique, use hash table. The main use of hash
tables is for looking up fixed information from a key. So if you have a report
that has personnel number and you want to display their name, you could use a
hash table.
Thus:
Code:
types: begin of typ_pernr,
pernr like pa0001-pernr,
ename like pa0001-ename,
end of typ_pernr.
data: ls_pernr type typ_pernr,
lt_pernr type hashed table of typ_pernr with unique key pernr.
...
select pernr ename into table lt_pernr from pa0001.
...
loop at itab.
read table lt_pernr with table key pernr = itab-pernr
into ls_pernr.
write: ls_pernr-ename, itab-data.
endloop.
