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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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Fact table linked to Slowly Changing Dimension

I'm struggling to understand the best way to model a particular scenario for a data warehouse. I have a Person dimension, and a Tenancy dimension. A person could be on 0, 1 or (rarely) multiple tenancies at any one time, and will often have a…
paulH
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SSAS and Type 2 SCD Data

I am having trouble getting an expected result with SSAS and Type 2 SCD data. Below, I have listed the simple tables I am using, the output from SSAS that I am getting and the output from SSAS that I am hoping for. I feel SSAS should be able to…
wh4tshisf4c3
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My Slowly Changing Dimension in SSIS keeps changing when it's not supposed to

I have a SCD transform and when I rerun the same packages 47 records update even though nothing is updated. The only inconsistencies I see is that these 47 records begin with a number 01N, 10A, and etc. Also these all have identical business keys.…
user3512885
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Problems defining normalized SQL database schema with recursive relationships and empty values

I have a question regarding the correct implementation of a Schema that I'm currently wrecking my head with: We have machines, which consist of components, which consist of parts. However, the relationships are as follows: Machines (1) -->…
mmmarius
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How to implement SCD type 3

A customer is changing the address let say 5 times. How to implement CUSTOMER dimension using slowly changing dimension type 3?
Kamlesh Khollam
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Generic procedure to perform SCD in sql

I have 2 tables in mssql server.I can perform scd through custom insert/update/delete and also through Merge statement. Awesome Merge I want to know that is there any generic procedure that could server the purpose. we just pass it 2 tables and…
user1765876
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How to get start date and end date in sql?

I have a small table that looks like this: PLAN YRMTH A2BKG 197001 A2BKG 200205 A2BKG 200308 A2BKG 200806 From this table, how do I get a table such as the one below? PLAN STARTDATE ENDDATE A2BKG 197001 200205 A2BKG …
Sarah
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Workaround for no SCD0 in SSIS Dimension Merge SCD Component?

First of all let me just say, I know, there is such thing as SCD0 in Kimball's definition... however, the SSIS SCD wizard has a provision for "Fixed Attribute" and I have a design case where I legitimately need what has been unofficially dubbed…
tlum
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How to use schema component designators in xerces for java?

I want to run SCD queries on a schema. The docs indicates that there is experimental support, but I don't see anything in the javadoc. Anyone know how it's supposed to work?
jiggy
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PostgreSQL: Foreign key to a table with SCD 2

Using a foreign key to connect two simple tables is straight forward in PostgreSQL: CREATE TABLE location ( id UUID PRIMARY KEY, name TEXT ); CREATE TABLE event ( id UUID PRIMARY KEY, location_id UUID, title TEXT, FOREIGN…
Filchos
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SCD TYPE 2 Implementation

Needs to implement SCD TYPE 2 Table in SQL server. Which insert new record and update timestamp if Threshold Values changes for particular Band. If no changes found then doesn't touch the…
Gaurav Jan
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LM_36320 Session task instance [s_m_scdone]: Execution failed

Please help me out im getting this error in informatica powercenter in workflow monitor. After starting workflow i'm getting this error LM_36320 Session task instance [s_m_scdone]: Execution failed. How to solve this error??
Shanmugavalli K
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Efficient processing of Data in Data Lake

I need to efficiently process data in Datalake without using the partition key. Is there any effective methods available, please let me know. Tried to build method to Update data efficiently in Data Lake using the partition key, but I am unable to…
Ajithkumar
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SQL SCD2 weekly statistic grouped by shipping date

I've been having one of those weeks... I am creating a simple POC for the Director, who is looking for weekly stats of order values shipping. The scenario they asked is "At the end of each week (Sunday), I want to see the orders total ($), for the…
a.Smith
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Is there a way to use SCD Type 0 in Talend component for Redshift

I'm using a component called tJDBCSCDELT to create and load data in a SCD in Redshift. Everything works fine if I use SCD Type 1 & 2. But if I use SCD Type for my load_date this is where things tends to go south. Does anyone have experience with…
Seka
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