if you want a internal table which allows faster reading then you should go for hashed table , but the disadvantage is that you cannot use index to read the hashed itab.
you have to use keys.
sample declratin of hashed table.
data:cc_text TYPE HASHED TABLE OF /bi0/tcostcenter WITH UNIQUE KEY co_area costcenter langu .
to read entries from the hashed table.
READ TABLE cc_text INTO wa_cc_text WITH KEY
co_area = coarea
costcenter = cctr
langu = sy-langu .
Hash table access time dosent increase based on the number of records, its constant.
check out the ABAP key work documentation for different types of internal table and their usages.
> How Hash Algorithm and Logarithmic Algorithm works
> to fetch the data ?
Fetching part is the same as standard internal table, only when you work with the internal table, than it's different.
> What the basic things we have to keep in mined when
> we select the Internal table ?
Eg Performance.
> Any rule for selecting the internal table which
> should be followed ?
Standard table is quite easy to use, but you might loose performance with it. Most of the time hash table is the fastest.
Using standard table and sort it is a good choice, when you access in READ TABLE via BINARY SEARCH.
Check 'ABAP for Power Users' SAP tutorial in SDN, it very good explains this topic in detail.
http://www.sap.info/public/en/category.php4/Category-28943c61b1e60d84b/page/0/article/Article-119884...
Regards,
Pavan
Bluesky
