when will we use unconnected & connected lookup? How it
will effect on the performance of mapping?
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Answer / sweta kedia
A. Connected Lookup
Receives input values directly from the pipeline.
We can use a dynamic or static cache
Supports user-defined default values
Unconnected Lookup
Receives input values from the result of a :LKP expression
in another transformation.
We can use a static cache
Does not support user-defined default values
When you compared both basically connected lookup will
return more values and unconnected returns one value. conn
lookup is in the same pipeline of source and it will accept
dynamic caching. Unconn lookup don't have that faclity but
in some special cases we can use Unconnected. if output of
one lookup is going as input of another lookup this
unconnected lookups are favourable
Moreover if the mapping requires multiple lookup using same
lookup conditions then its better to use unconnected lookup
& call the lookup wherever required.This also prevents the
mapping from being complex.
| Is This Answer Correct ? | 3 Yes | 0 No |
Answer / v.ramakrishna
when it comes to the matter of performance optimization we
can understand the diff between conn lookup and unconn
lookup y bcoz in conncted lookup it will give more than one
output. when compared with the performance of unconn lookup
it is some what slower bcoz the execution times in conn
lookup is equal with no of records present in source . so
it will increase running time . where as in unconn lookup
it executes only for records which satisfy the given
condition so no need to call lookup for each and every
record unneccesarily. so it leads to performance
development in unconn lookup compared wth conn lookup.
| Is This Answer Correct ? | 3 Yes | 1 No |
Answer / nag
Connected Lookup
Receives input values directly from the pipeline.
We can use a dynamic or static cache
Supports user-defined default values
Unconnected Lookup
Receives input values from the result of a :LKP expression
in another transformation.
We can use a static cache
Does not support user-defined default values
When you compared both basically connected lookup will
return more values and unconnected returns one value. conn
lookup is in the same pipeline of source and it will accept
dynamic caching. Unconn lookup don't have that faclity but
in some special cases we can use Unconnected. if output of
one lookup is going as input of another lookup this
unconnected lookups are favourable
| Is This Answer Correct ? | 2 Yes | 1 No |
Answer / jeevan kumar medapati
if u want to perform look up on less values then we go for
connected lkp
if u want to perform look up from more than one table then
we go for un connected lkp
in ur source u have more date columns then we should go for
unconnected lkp.
| Is This Answer Correct ? | 1 Yes | 1 No |
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