What are slowly changing dimensions?
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Answer / sri ram
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 ? | 36 Yes | 5 No |
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 ? | 27 Yes | 2 No |
Answer / anitha
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 ? | 11 Yes | 0 No |
Answer / chaitanya
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 |
Answer / ande
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 |
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