DataStage - Join and Lookup Stage

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Join and Lookup Stage

If you have a huge volume of data to be referenced, which stage will you use? Join or Lookup stage? Why

Total Answers and Comments: 4

Last Update: July 24, 2008 Asked by: datastage8

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Submitted by: swapnilverma

Hi

for huge size of data we must use join.

Lookup stage requires all the data to be loaded in memory 1st & then only it can start matching process with inputs.

Hence It is advisable to use join stage then Lookup stage.

If you want to capture Reject records then you can use transformer (or filter) after Join Stage and capture the null values.
Or Instead of join stage use Merge Stage to capture the reject records.

Hope this helps

Above answer was rated as good by the following members:
anujk_arora

February 27, 2008 03:09:23

sqlquiz82

Member Since: October 2007 Contribution: 4

RE: Join and Lookup Stage

if the reference datasets are big enough use a join. A join does a high-speed sort on the driving and reference datasets.Once the sort is over the join processing is very fast

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April 18, 2008 14:34:50

ramu_open

Member Since: April 2008 Contribution: 1

RE: Join and Lookup Stage

join has no reject links. wheras lookup has one reject link
join has 4 types inner outer left outer rght outer. l0ok up gives inner and left outer
lokk up takes any kind of colmn names and perform join operations.join needs same coloumn names among all sources.
if refernce table has little data prefer to lookup more means prefer join..

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April 30, 2008 03:02:34

swapnilverma

Member Since: February 2008 Contribution: 2

RE: Join and Lookup Stage

Hi

for huge size of data we must use join.

Lookup stage requires all the data to be loaded in memory 1st & then only it can start matching process with inputs.

Hence It is advisable to use join stage then Lookup stage.

If you want to capture Reject records then you can use transformer (or filter) after Join Stage and capture the null values.
Or Instead of join stage use Merge Stage to capture the reject records.

Hope this helps

Is this answer useful? Yes | No

1 0

Overall Rating: +1

July 24, 2008 10:43:37

kotig

Member Since: July 2008 Contribution: 1

RE: Join and Lookup Stage

use the lookup stage when the reference table size is less relative to physical ram memory
if the reference table size is too big then data stage recommends to use the join stage to speed up the join process

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