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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
 
  Question Asked @ Answers
 
SOURCE NAME SAL GANGA 30000 RAJU 20000 PAVAN 25000 TARGET NAME SAL MAXSAL GANGA 30000 30000 RAJU 20000 30000 PAVAN 25000 30000 in mapping level how to achive that DELL 5
I have a scenario with lookup table. in that lookup table have colomns, but i need to process only 10 colomns out of 50. Please te me how can we acheive it? TCS 6
can we create index and drop index in exsisting table while using infomatica   4
Can we create out put ports in source qualifier t/r? tcs 5
in unconnected lookup , what are the other transformations , that can be used in place of that expression transformation ? Target 9
what is the necessity to use update strategy?(except for updates) Emphasis 2
i have flatfile source. i want to load the maximum salary of each deptno into target. what isthe mapping flow Wipro 2
what is normalizer transformation? Wipro 4
In a simple mapping when i use aggregate t/r with out any condition or group by, i am getting output as only last record in the table . can any one explain it please.........?   3
how remove 1st 3 records & last 3 records in informatics TetraSoft 4
What is a design?   1
2,can we insert duplicate data with dynamic look up cache,if yes than why and if no why? TCS 2
 
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