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Question
What are the types of lookup?
 Question Submitted By :: Informatica
I also faced this Question!!     Answer Posted By  
 
Answer
# 1
Differences Between Connected and Unconnected Lookup:
connected

o Receives input values directly from the pipeline.

o uses Dynamic or static cache

o Returns multiple values

o supports user defined default values.

Unconnected

o Recieves input values from the result of LKP
expression in another transformation
o Use static cache only.
o Returns only one value.
o Doesnít supports user-defined default values.
NOTES
o Common use of unconnected LKP is to update slowly
changing dimension tables.
o Lookup components are
(a) Lookup table. B) Ports c) Properties d) condition.

Lookup tables: This can be a single table, or you can
join multiple tables in the same Database using a Lookup
query override.You can improve Lookup initialization time
by adding an index to the Lookup table.
Lookup ports: There are 3 ports in connected LKP
transformation (I/P,O/P,LKP) and 4 ports unconnected LKP
(I/P,O/P,LKP and return ports).
o if youíve certain that a mapping doesnít use a
Lookup ,port ,you delete it from the transformation. This
reduces the amount of memory.
Lookup Properties: you can configure properties such as SQL
override .for the Lookup,the Lookup table name ,and tracing
level for the transformation.
Lookup condition: you can enter the conditions ,you want
the server to use to determine whether input data qualifies
values in the Lookup or cache .
when you configure a LKP condition for the transformation,
you compare transformation input values with values in the
Lookup table or cache ,which represented by LKP ports .when
you run session ,the server queries the LKP table or cache
for all incoming values based on the condition.
NOTE
- If you configure a LKP to use static cache ,you
can following operators =,>,<,>=,<=,!=.
but if you use an dynamic cache only =can be used .

- when you donít configure the LKP for caching ,the
server queries the LKP table for each input row .the result
will be same, regardless of using cache
However using a Lookup cache can increase session
performance, by Lookup table, when the source table is
large.
Performance tips:
- Add an index to the columns used in a Lookup
condition.
- Place conditions with an equality opertor (=) first.
- Cache small Lookup tables .
- Donít use an ORDER BY clause in SQL override.
- Call unconnected Lookups with :LKP reference
qualifier.
 
Is This Answer Correct ?    15 Yes 2 No
Sandeep
 
Answer
# 2
Connected and unconnected 
Is This Answer Correct ?    8 Yes 7 No
Swetha
 
 
 
Answer
# 3
CONNECTED /UNCONNECTED
CACHE/UNCACHE
 
Is This Answer Correct ?    3 Yes 5 No
Rekha
 

 
 
 
Other Informatica Interview Questions
 
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Find a way to implement the following logic : You have column like : Column 1 AA|BB|CC DD|EE|FF WW|AA I need to get the length of the column without the Ď|í .   5
i have source like X1 10 X2 20 X1 30 X2 40 i want target as X1 X2 10 20 30 40 in informatica HP 2
what are the output files that the informatica server creats during running a session? CTS 2
I have table name in that I have Rajesh Reshika Priya I want the result Like only Starting with R Rajesh Reshika Can someone help me to get these results and How?   3
1:when we develop a project what are the performance issue will raise?? KPIT 2:if a table have INDEX and CONSTRAINT why it raise the performance issue bcoz when we drop the index and disable the constraint it performed better??KPIT 3:what are unix commands frequently used in informatica?? KPIT 1
what is incremantal aggregation?   1
how to get the only updated records in the target   2
When the informatica server marks that a batch is failed?   1
What are the reusable transforamtions?   2
Define maping and sessions?   3
How to do Half of the table ex: if 1000 records are there means 500 in one table and 500 in second table like this if N number of tables means how to do Half of the table ?????????? TCS 2
How do we eliminate duplicate records in a flat file without using Sorter and Aggregator? iNautix 6
 
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