What is the difference between Connected and UnConnected
Lookup Transformation.Give me one or two examples please?

Answer Posted / jaimeen shah

1) Connected lookup receives input values directly from the
pipeline whereas Unconnected lookup Receives input values
from the result of a :LKP expression
in another transformation.

2) You can use a dynamic or static cache in connected
lookup whereas in connected lookup you can use static cache
only.

3) In connected lookup, 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) whereas in
unconnected lookup, Cache includes all lookup/output ports
in the lookup condition and the lookup/return port.

4) Connected lookup can return multiple columns from the
same row or insert into the dynamic lookup cache whereas
Unconnected lookup designate one return port (R). Returns
one column from each row.

5) In connected lookup, 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.
In unconnected lookup, If there is no match for the lookup
condition, the PowerCenter Server returns NULL.

6) Connected lookup pass multiple output values to another
transformation. Link lookup/output ports to another
transformation.
Unconnected lookup pass one output value to another
ransformation. The ookup/output/return port passes the alue
to the ransformation calling :LKP expression.

7) Connected lookup supports default values in the port
whereas unconnected lookup doesn't support the default
values.

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