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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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Datawarehouse: Multivalued Slowly Changing Dimensions

I am currently creating a datwarehouse for a (coffee) aggregator in latin america. They have two main business operations: buying coffee from farmers and selling it in the international market and providing micro-credit loans to these farmers…
Lucasvw
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Remove repeating interval/history duplication

It's a bit a challenge to put the proper Title to that question, so I'll try to explain the problem. We have Oracle --> SQL Server replication using JCC. The way it works, that it reads the transaction log in Oracle and then with every change it…
Dmitrij Kultasev
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SCD Type 2 End Date issue

I'm struggling with recording a Slow Changing Dimension (SCD). I have a daily ETL job that registers versions of records based on changes. The problem is that I'm getting End Dates bigger than the Start Date of the current version. What I should be…
MrM1k4d0
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SSIS SCD Transform Start Date and End date are the same - how can this be?

I have an issue with my ETL. I have a dimension table that has some SCD 1 and SCD 2 columns - I have mapped these correctly in the SCD Transformation as Changing Attribute and Historical Attribute respectively. Then on the Historical Attribute…
MadDog
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SQL Server SCD II implementation quandary

I have a patient table with north of 80 fields, of which I'll need to keep historical data on all fields. For clarification, not all fields "need" versioning, though the decision was made to simply keep a full copy of the old records. For…
Eli
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SCD in BIDS 2016 SSIS

I am trying to achieve Type 2 SCD using SCD transformation. When I update something in the source, instead of updating that row alone, SCD transformation is updating and inserting all the rows. Example, soruce has 50 rows and destination has same…
Ajoy
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Get all Valid time slices in a Table

I have a table in which the entries are historized with SCD 2 Now I am looking for a possibility to get Alle PK which are valid at the same time: For example my table Look like…
AmBlack
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BIML SCD component

In SSIS we have the basic SCD component to refresh Dimension tables. I was looking to use it via BIML, but the component does not seem to exist... Is there a way in BIML to refresh a Dim ? Thanks in advance
drb
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SQL Server - Slowly Changing dimension join

I have a fact table and employee "tier" table, let's say. So the fact table looks sorta like employee_id call date Mark 1 1-1-2017 Mark 2 1-2-2017 John 3 1-2-2017 Then there needs to be a data…
user45867
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SCD type2 example implementation in sql developer

I am trying to implement a example of SCD type2. so i am creating a table with empid,ename,location,hiredate,startdate,enddate and a flag. now initally suppose hiredate and startdate be 01-jan-2012 and enddate by default is 01-jan-2099. and for…
Akansha Kaushik
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SSAS & SCD2 - how to deal with IsActive row in Dim

I am using SQL Server 2014 and Visual Studio 2015. I have an SCD2 for staff names, for example SK AltKey Name Gender IsActive 1 15 Sven Svensson M 1 2 16 Jo Jonsson M …
user3735855
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Need help understanding alternatives to scd in SSIS

I am working on a data warehouse project that will involve integrating data from multiple source systems. I have set up an SSIS package that populates the customer dimension and uses the slowly changing dimension tool to keep track of updates to the…
Derek Miller
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Slowly Changing Dimension Type 1 - access

Say I have a product table which contains a descriptions mistake. The unit of measurement was misspelled as “garms” instead of “grams”. How would this be implemented with a query statement to represent type 1 - SCD technique.
Lulutho Mgwali
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Understanding Slowly Changing Dimension Type 2

I am having difficult time understanding how to use slowly changing dimension type 2, in my scenario. I have gone through different tutorial websites but they don't fit. I have an employee dimension table…
Miru
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Using a date field for matching SQL Query

I'm having a bit of an issue wrapping my head around the logic of this changing dimension. I would like to associate these two tables below. I need to match the Cost - Period fact table to the cost dimension based on the Id and the effective…
Channing
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