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Categories >> Software >> Data Warehouse >> Informatica
 
 


 

 
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Question
What are slowly changing dimensions?
 Question Submitted By :: Informatica
I also faced this Question!!     Answer Posted By  
 
Answer
# 1
Slowly Changing Dimensions:(SCD)
Over period of time, the value /data associated with
dimensions may change. To track the changes we record the
changes as per the requirement.
There are three types of SCD
SCD 1:No history is maintained. As and when data comes, the
data is entered.
SCD 2: History is maintained
SCD 3: Partial History is maintained.
We maintain history for some columns but not for all.
For example,I have 3 records in a dimension
I have made 1 insert and 1 update. Then if the requirement
is that dimension is to be maintained
In SCD 1 Then
Total number of records is 4 records(1 insert & 1 update)
In SCD 2 Then
Total number of records is 5 records(1 insert & 1 update)
In SCD 3 Then
Total number of records is 4 records(1 insert & 1 update)
NOTE:
History means the slight change in the data stored and
incoming data but it doesn't means years of data.
 
Is This Answer Correct ?    34 Yes 4 No
Sri Ram
 
Answer
# 2
DIMENSIONS ARE CLASSIFIED INTO THREE TYPES
SCD TYPE-1 (MAINTAIN CURRENT DATA)
SCD TYPE-2 (MAINTAIN CURRENT DATA+FULL HISTORY OF CHANGES)
SCD TYPE-3 (MAINTAIN CURRENT DATA+ONE TIME HISTORY)
 
Is This Answer Correct ?    26 Yes 2 No
Sandeep.t Nizamabad
 
 
 
Answer
# 3
scds are three types.
type1:it stores the current data.

type2:it stores the full historical data.

type3:it stores the current and previous data in the target...
 
Is This Answer Correct ?    10 Yes 0 No
Anitha
 
Answer
# 4
SCD, is a technique used to store the historical value of
dimension attributes.

The values of dimensional attributes change as time goes by.
When these attribute values change, you can overwrite the
old values with the new ones, or you can
preserve the old value.

There are two methods of preserving the old attribute
values: you can store the old values as rows, or you can
store them as columns

three types of SCD:
SCD type 1 overwrites the old values of the attributes so
the old values are not kept.
Ex: In product dimension,we will use SCD type 1, meaning we
will overwrite the old attribute values.

SCD type 2 keeps the old values by creating a new row for
each change.
SCD type 3 keeps the old values by putting them in another
column
 
Is This Answer Correct ?    0 Yes 1 No
Chaitanya
 
Answer
# 5
there are three types SCD:
type-1: in this we can over write original recourd with new
record
type-2: we can create new record
type-3: we can create new attribute
regards,
ande
 
Is This Answer Correct ?    9 Yes 23 No
Ande
 

 
 
 
Other Informatica Interview Questions
 
  Question Asked @ Answers
 
How to transform normalized data to denormalized form in informatica? Is there any logic or any transformations to achieve this?   3
if i have one mapping and we already tuned that mapping for performance,everything is fine and loading will take 1 hr,so without doing any change in mapping how could we reduce the loading time from 1hr to 1/2 hr. Wipro 4
if we have certain records,if i need to get 5 th rec for the first time to the target,when i run it for next time,i need to get 6th rec...like that it should process.what wil be the procedure to achieve it?? IBM 1
why do u use shortcuts in informatica.? iFlex 4
HOW CAN U FIND THE SESSION START TIME? chandumba2005@gmai.com TCS 2
how can import the data from the flat files?   2
how to sort date field in infomatica?   2
what is upstream and downstream transformation?   7
HI Experts, What is BULK mode and NORMAL mode, Which one gives better performance. How? Please Explain with an example...! It will help's me a lot. Thanks In advance. CTS 7
TWO FLAT FILES ARE THERE , EACH HAVING NO MATCHING COLUMNS . HOW CAN U JOIN THESE TWO USING JOINER TRANSFORMATION ? HP 6
what is parameter file? Cap-Gemini 1
Why do flat file load is faster if you compare that with table load ? Please answer me. Advance Thanks, Manojkumar IBM 11
 
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