Connected v/s Unconnected Transformation

Tips :

want to know the use of unconnected transformation.

Why shd we use unconnected transformation, if we can achieve same with connected one?

Which gives better performance, connected or unconnected and why?

Answers 1 :
Depending upon the scenario we use the conn and unconn tr..

for e.g
In u r mapping u require same lkp multiple times,creating lkp multiple times put it in flow is not a good idea..which occupies more cache ...
Instead of that create one unconnectes lkp use multiple times where ever u want ..which very fast..

Answers 2:
u can use conn lookup but if u need 1 row so go for unconn lookup coz u can
use it multiple time in same mapping from multiple expression trn.
i hope it will help to u

Benefit :
The benefit of an unconnected lookup is that you can do conditional lookups (using IIF,DECODE, etc.). In other words, you can control when the lookup is used with in unconnected lookup.

unconnected lookup gives better performance because it's not connectd to mapping pipeline.
so when data transform is very fast compare to connected transformation.

unconnected look up can be used when you need only one port to be
returned from the look up table or if the same is to be used
many times in the mapping. and moreover unconnected lookup gives
better performance as it just acts as a function call. but if
more ports has to be returned from look up table we must use a
connected look up