Differences between connected and unconnected lookup?


Connected lookup

Unconnected lookup

Receives input values diectly from the pipe line.

Receives input values from the result of a  lkp expression in a another transformation.

U can use a dynamic or static cache

U can use a static cache.

Cache includes all lookup columns used in the maping

Cache includes all lookup out put ports in the lookup condition and the lookup/return port.

Support user defined default values

Does not support user defiend default values

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Prasanna

  • Feb 3rd, 2006
 

In addition:

Connected Lookip can return/pass multiple rows/groups of data whereas unconnected can return only one port.

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Girish

  • Aug 15th, 2006
 

In addition to this: In Connected lookup if the condition is not satisfied it returns '0'. In UnConnected lookup if the condition is not satisfied it returns 'NULL'.

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Shivat

  • Sep 13th, 2006
 

Hi

 Differences Between Connected and Unconnected Lookups
Connected Lookup
Unconnected Lookup
Receives input values directly from the pipeline.
Receives input values from the result of a :LKP expression in another transformation.
You can use a dynamic or static cache.
You can use a static cache.
Cache includes all lookup columns used in the mapping (that is, lookup source columns included in the lookup condition and lookup source columns linked as output ports to other transformations).
Cache includes all lookup/output ports in the lookup condition and the lookup/return port.
Can return multiple columns from the same row or insert into the dynamic lookup cache.
Designate one return port (R). Returns one column from each row.
If there is no match for the lookup condition, the PowerCenter Server returns the default value for all output ports. If you configure dynamic caching, the PowerCenter Server inserts rows into the cache or leaves it unchanged.
If there is no match for the lookup condition, the PowerCenter Server returns NULL.
If there is a match for the lookup condition, the PowerCenter Server returns the result of the lookup condition for all lookup/output ports. If you configure dynamic caching, the PowerCenter Server either updates the row the in the cache or leaves the row unchanged.
If there is a match for the lookup condition, the PowerCenter Server returns the result of the lookup condition into the return port.
Pass multiple output values to another transformation. Link lookup/output ports to another transformation.
Pass one output value to another transformation. The lookup/output/return port passes the value to the transformation calling :LKP expression.
Supports user-defined default values.
Does not support user-defined default values.

Shivaji Thaneru

ASHOK1324

  • Apr 21st, 2009
 

1]. Connected lookup receives input values directly from mapping pipeline whereas UnConnected lookup receives values from: LKP expression from another transformation.

2]. Connected lookup can use a dynamic or static cache. Unconnected lookup can use only static cache.

3]. Connected lookup returns multiple columns from the same row whereas UnConnected lookup has one return port and returns one column from each row.

4]. Connected lookup supports user-defined default values whereas UnConnected lookup does not support user defined values.

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