topic Re: hashed table or binary search on sorted table ? in Application Development and Automation Discussions

hashed table or binary search on sorted table ?

former_member5350 — Mon, 14 May 2007 07:37:51 GMT

hi friends,

just a quick question:

what is faster/ more performant ?

sort a table and then do a binary search on it or define the internal table as hashed table ?

thanks,

Re: hashed table or binary search on sorted table ?

Former Member — Mon, 14 May 2007 07:39:26 GMT

Hi,

Sort a table and do a binary search.

Jogdand M B

Re: hashed table or binary search on sorted table ?

Former Member — Mon, 14 May 2007 07:40:17 GMT

HI,

Defining table as Hashed is more Faster but you get issues in creating a Hased table..

Better use standard internal table and sort it and read via Binary search..

Hope most of the development uses the above criteria..

regards,

nazeer

Re: hashed table or binary search on sorted table ?

Former Member — Mon, 14 May 2007 07:43:25 GMT

Hi Clemens,

Define an internal table as Hash table is always gives more performance than SORTing the internal table with BINARY SEARCH option.

SORT statement will take time on internal table and BINARY SEARCH will get an entry in log n time where n is the no of entries in a table.

In Hashed table, each entry will be stored and picked up by using an Hash key. Hashing is always the faster than BINARY SEARCH.

The Hash key is generated by using Hash algorithm. You can find difference when you had huge volume of data.

Thanks,

Vinay

Re: hashed table or binary search on sorted table ?

Former Member — Mon, 14 May 2007 07:43:59 GMT

Hi,

Hashed table will be a better choice as it will map the key directly and the time required to get the particular key value remains constant.

But in Binary search the situation is different.

In this the time to get the key value is not constant.

Thanks & Regards

Santhosh.

Re: hashed table or binary search on sorted table ?

seshatalpasai_madala — Mon, 14 May 2007 07:59:54 GMT

Hi,

Hashtable is better as you always access it using the KEY, where as SORT and BINARY SEARCH is not always going to give you the results there can be scenario's were your search may not find the record you are looking for when you use SORT and Binary Search.

Best Regrds,

Sesh

Re: hashed table or binary search on sorted table ?

Former Member — Mon, 14 May 2007 14:03:10 GMT

Hi Clemens,

Hash tables use an algorithm that defines all the entries in the internal table as a unique record. Thus searching for any record takes the same time (constant time) irrespective of the size of the table. Hash tables are the most efficient way (better than standard tables with binary search or sorted tables) to search for records in very large tables using a Key. The disadvantage is that the you cannot use INDEX to retreive data from this table (you cannot say READ TABLE itab INDEX <record number> or MODIFY itab INDEX <record number> TRANSPORTING <field list> for example). You can use Hash tables only if you are absolutely sure that you are not going to use the INDEX clause. As long as your records have a unique key(s), using hash table will give you a huge performance gain when dealing with large dataset.

Regards,

Mark

Re: hashed table or binary search on sorted table ?

harishaginati — Tue, 15 May 2007 06:03:58 GMT

Hi Buddy...,

you can justify this answer based on <b>onlyyy volume of data(number of records) in your internal table</b>

if you have low volume of data go for Sorted table which is faster then hash table, if you have relatively high amount of data go for hashed table...,

hope you are clear now.., reward me if helpfull.

cheers,

Harish

Re: hashed table or binary search on sorted table ?

Former Member — Tue, 15 May 2007 09:24:06 GMT

hi Clemens

Hashed table is good always...This is the most appropriate type for any table where the main operation is key access. You cannot access a hashed table using its index. The response time for key access remains constant, regardless of the number of table entries. Like database tables, hashed tables always have a unique key. Hashed tables are useful if you want to construct and use an internal table which resembles a database table or for processing large amounts of data.

Sample Prog: This does nothing.

REPORT Z_1 .

tables: mara.

data: i type hashed table of mara with unique key matnr.

REWARD IT PLEASE...!!