Difference between Join and Lookup

prasad v · Post by **prasad v** » Tue Jun 30, 2009 6:09 am

Hi

I wanted to know the when can we use the JOINER AND LOOKUP.

I am new to DS. I am studying the Pdf's .

What is understood is if reference link haveing more data we should go to Joiner.

My doubt is that if we use in-memory method in Lookup then only it takes the whole data to server memory and lookup's the input link. If we use Sparse method, it doesn't take the whole data to server memory.

nagarjuna · Post by **nagarjuna** » Tue Jun 30, 2009 6:11 am

thts correct ...for more information you can search the forum ..

Sreenivasulu · Post by **Sreenivasulu** » Tue Jun 30, 2009 7:20 am

Join , Lookup and merge have lot of similarities.

Regards
Sreeni

ray.wurlod · Post by **ray.wurlod** » Tue Jun 30, 2009 4:43 pm

... but very important subtle differences.

sajidkp · Post by **sajidkp** » Tue Jun 30, 2009 9:53 pm

1.join will take only one partition data of master (reference table) at a time in memory where as lookup (sparse) take all the data in to memmory

2. We can have reject link in lookup . not possible in joiner

3.joiner is good if data volume is huge.

jonyfranc · Post by **jonyfranc** » Tue Jun 30, 2009 10:49 pm

The Join, Lookup and Merge stages combine two or more input links according to values of key columns. They differ mainly in memory usage, treatment of rows with unmatched key values and input requirements i.e. sorted and de-duped

Francis