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Questions tagged [scd]

Slowly Changing Dimensions or Schema Component Designator

SCD may refer to Slowly Change Dimension transformation for SQL Server or Schema Component Designators which is a declarative query language for XML Schemas.

Slowly Changing Dimensions in data management and data warehousing are relatively static dimensions containing entities. Data captured by SCD changes slowly rather on unpredictable time interval. In the data warehouse they are used for reporting historical data.

Slowly Changing Dimension Techniques :

  1. Type 0 - retain original. Dimensions attributes never change, so facts are always grouped by original value.
  2. Type 1 - overwrite. The old attribute value in the dimension is overwritten with the new value.
  3. Type 2 - add new row. It adds a new row in the dimension with an updated attribute values.
  4. Type 3 - add new attribute. It adds a new attribute in the dimension to preserve the old attribute value.
  5. Type 4 - add mini-dimension. When a group of attributes changes rapidly and it split off to a mini-dimension.
  6. Type 5 - add mini-dimension and Type 1 outtriger. Used to accurately preserve historical attributes values, plus report historical fact according to current attribute value.
  7. Type 6 - add Type 1 Attributes to Type 2 Dimension. Like Type 5, Type 6 delivers both historical and current dimension attribute values. Type 6 builds on the Type 2 technique by also embedding current type 1 versions.
  8. Type 7 - dual Type 1 and Type 2 dimensions. Final hybrid technique used to support as-was and as-is reporting.

More information on Slowly Changing Dimensions:

  1. Kimball Dimensional Modeling Techniques
  2. Wikipedia
  3. Slowly Changing Dimensions by Ralph Kimball
  4. Slowly Changing Dimensions Are Not Always as Easy as 1, 2, 3
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New to Data Warehousing and Data Marts

I'm completely new to Data Warehousing and Marts and wanted to ask for some advice on the best resources to learn and gain knowledge to start me off on the right path. I have a project to work on but need some guidance or somewhere to start really.…
Andy_RC
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DataModel for Implementing row versioning in OLTP system

I have following table Person(PID, Name, Dob, AddressId) PID being surrogate key(auto incremented) Address(AddressId, Line1, Line2, City, State) AddressId being surrogate key(auto incremented) PersonID (PID) is used in my lot of transaction…
Shantanu Gupta
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Slowly changing dimension by date only

I have a database table using the concept of data warehousing of slowly changing dimension to keep track of old versions. So, I implemented it with the Log Trigger mechanism. My table is like this: CREATE TABLE "T_MyTable" ( "Id" INT NOT NULL…
Nova
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SSIS 2012 - setting slowly changing dimension UpdateChangingAttributeHistory to true

Using the SCD task wizard, I am unable to set the UpdateChangingAttributeHistory property and it defaults to false. I am able to set this to true using the advanced editor, but this does not update the generated flow and therefore the behavior has…
Neil P
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Managing Slowly Changing Dimension with MERGE Statement in SQL Server

I am trying to build a Slow Changing Dimension Table with T-SQL since I notice I can not used the SCD in SSIS because I have a large data. I need your help My table structure: CREATE TABLE [dbo].[Customer] ( [BusinessEntityID] [int] PRIMARY KEY…
Pabartho
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How to join a fact table to a (Kimball type 2?) slowly changing date in SAS

New to SQL - I'd like to join the fact table crselist to the crseinfo table to get the correct dimension info. I've been working on some correlated subqueries but none give the desired result (below). The crseinfo table says that beginning in…
Wes McClintick
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Performance of concatenated column - does order matter?

I need to create a concatenated column based on two other columns in the table. One column is the year (10 distinct values), and one is a person's ID value (~150,000 distinct values). This is being used as a business key by an ETL task that will…
AHiggins
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SCD type 2 with parent-child hierarchy aggregation issue

We have a staff dimension that has a self-reference for managers (Parent-Child relationship) that we built the hierarchy on it. DimStaff table: | SurrogateKey | BusinessKey | Employee Name | ManagerBusinessKey | StartDate | EndDate | | 1…
GoodHeartedOne
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DWH import with surrogate keys (and SCD)

I have a Data Warehouse which uses internal surrogate keys and type 2 slowly changing dimensions. In the clearing we just have the business keys from the erp-system, like this: In the Data Warehouse we want to use the surrogate keys instead (Note:…
Josh Alvo
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SSIS slowly changing dimension type 2 on historical data

I have to load the below data set onto a dimensional table, I need to check for Slowly Changing Dimension type 2 on Contribution column. There's historical data on the below dataset, I'm required to load all records including the historical data and…
John W. Mnisi
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Does the System::CreationDate in the Slowly Changing Dimension have something to do with the date when the ssis package was created?

I created an SSIS package composed of OLE DB Source connected to an SCD. Inside the SCD, I ticked the radio button for "Use start and end dates to identify current and expired records" I choose Start Date column: RecordStartDate End Date column:…
BA82283
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Textrevisioning in MySQL

at the moment I am working on a cms that should support text revisioning. Because sometimes I tend to overcomplicate things I thought I ask here for improvements and advise. I have the following 4 tables: article ID INT PK createdAt…
Tobias Golbs
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Split data by Date

I am importing a .CSV file for an HRIS project that will report New Hires and Terminations. I have one report that shows the following date. |PersNo|Name|EntryDate|TermDate| I want to split the date so that the people with the Term dates go into…
Brian D. Brubaker
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SCD and command task is not working

Slowely changing dimension task is not working in data flow task.. but if I remove it and use the OLEDB destination it is inserting the data. I have no idea why it is not inserting data into the table. SCD and leaf task is also not converting to…
Zerotoinfinity
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MySQL Slowly changing dimensions SCD2 + ON DUPLICATE KEY UPDATE

Im looking to have MySQL handle Slowly changing dimensions The table is set up to use 'effective date' as the control - so table structure is similar to here http://en.wikipedia.org/wiki/Slowly_changing_dimension Type II bottom example. Is it…
exussum
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