What are the mapings that we use for slowly changing
dimension table?
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Answer / surya
slowly changing dimensions can be classified by three types.
1)Type1:In this dimension we can store only current data
and here insert are treated as inserts and updates are
treated as updates.
2)Type2:In this dimension we can store complete historic
data and it can divided into three types
a)Flag
b)Version
c)Date Range
But in type2 inserts are treated as inserts and updates are
treated as inserts.
3)Type3:In this dimension we can store One time historic
data with current data.Here also inserts are treated as
insert and updates are treated as updates.
It's depend upon the granularity of the organization.
| Is This Answer Correct ? | 4 Yes | 0 No |
Answer / swetha
Type1: Rows containing changes to existing dimensions are
updated in the target by overwriting the existing dimension.
In the Type 1 Dimension mapping, all rows contain current
dimension data.
Use the Type 1 Dimension mapping to update a slowly changing
dimension table when you do not need to keep any previous
versions of dimensions in the table.
Type 2: The Type 2 Dimension Data mapping inserts both new
and changed dimensions into the target. Changes are tracked
in the target table by versioning the primary key and
creating a version number for each dimension in the table.
Use the Type 2 Dimension/Version Data mapping to update a
slowly changing dimension table when you want to keep a full
history of dimension data in the table. Version numbers and
versioned primary keys track the order of changes to each
dimension.
Type 3: The Type 3 Dimension mapping filters source rows
based on user-defined comparisons and inserts only those
found to be new dimensions to the target. Rows containing
changes to existing dimensions are updated in the target.
When updating an existing dimension, the Informatica Server
saves existing data in different columns of the same row and
replaces the existing data with the updates.
| Is This Answer Correct ? | 3 Yes | 0 No |
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