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What r the mapings that we use for slowly changing dimension table?

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

Asked by: Interview Candidate | Asked on: Sep 21st, 2004
Showing Answers 1 - 5 of 5 Answers
mamatha

Answered On : Jun 3rd, 2006

hello sir,i want whole information on slowly changing dimension.and also want project on slowly changing dimension in informatica.Thanking you sir,mamatha.

  
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Sravan Gopisetty

Answered On : Sep 24th, 2006

1.Up Date strategy Transfermation2.Look up Transfermation.

  
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Arvind Kumar

Answered On : Jan 29th, 2007

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.

  
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Rp

Answered On : Oct 4th, 2007

SCD:
Source to SQ - 1 mapping,
SQ to LKP - 2 mapping,
SQ_LKP to EXP - 3 Mapping,
EXP to FTR - 4 Mapping,
FTR to UPD - 5 Mapping,
UPD to TGT - 6 Mapping,
SQGen to TGT - 7 Mapping. I think these are the 7 mapping used for SCD in general;For type 1: The mapping will be doubled that is one for insert and other for update and total as 14.For type 2 : The mapping will be increased thrice, one for insert, 2nd for update and 3 to keep the old one. (here the history stores)For type three : It will be doubled for insert one row and also to insert one column to keep the previous data.CheersPrasath

  
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ASHOK1324

Answered On : Apr 21st, 2009

View all answers by ASHOK1324

The Dimensions are classified 3 types.
1.SCD TYPE1 (Slowly Changing Dimension) : contains current data.
2.SCD TYPE2 (Slowly Changing Dimension) : contains current data + complete
historical data.
3.SCD TYPE3 (Slowly Changing Dimension) : contains current data + recent
historical data.

  
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