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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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Schema Component Designators (SCD) in Xerces?

From the Xerces2 Java Parser Readme page ,Changes from Previous Release section: This release also introduces experimental support for XML Schema Component Designators (SCD) I have been going through the Javadoc and cannot for the life of me…
Marcus Mathioudakis
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The right way to model multiple FACTs schema

Background I'm in a process of designing a database (using a STAR schema). There are three tables to model: products, tests, states. The database will be used to store results of tests conducted on products (in a great simplification). There can be…
Maciejo95
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MS SQL Server: best way to transform table to SCD

I need to transform a simple historical table to slowly changing dimention (exmpl below). What is the most efficient way to do that? Input ID - Update_date ---------- 143432 - '2019-02-03' 143432 - '2019-11-01' 143432 - '2020-03-16' Output ID -…
Grigory P
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Teradata join with SCD type 2

How to join transaction table and SCD table to get records from SCD according to date of transaction. Select A.id, A.trans_dt, trans_amt, B.pmt_meth from trans1 A left join scd1 B on A.id=B.id Now I need to get pmt_meth for each transaction. so…
Ganesh
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PowerBI: Find all records valid on specific date

I have a classic datawarehouse with records. Each record has a valid_from and a valid_to date. Now I want to set a filter in PowerBI. The idea is that the user somehow sets a date and all records for which this date falls between valid_from and a…
Henrov
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datastage scd stage is updating old records instead of inserting no match business keys

we have dim build with 1.8 million records and scd is updating the old records instead of inserting the record when business key is not found. need immediate help as this is a production issue.... we had identity on the destination table and we are…
indraneel
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How to read .scd data files with in a mfc application

I just purchased and installed a application from 3 Cds using registration key in pendrive. After installation, I just got a MFC Application (.exe). When i viewed the files, I found a data folder inside which I found many .scd files. The data is…
lara1435
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Can we get INSERT UPDATE Count from Slowly Changing Dimension Type-2 stored procedure?

How to get Insert Count = ? Update Count = ? in slowly changing dimension type 2 ? Here is my procedure CREATE PROCEDURE dbo.MergeDimCustomer AS BEGIN DECLARE @CurrentDateTime datetime DECLARE @MinDateTime datetime DECLARE @MaxDateTime…
Vedant Desai
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What is the purpose of "Change Tracking" in SCD Type-2 Loader in SAS?

What is the purpose of "Change Tracking" in SCD Type-2 Loader in SAS ? What is Start date and end date time ?
Ayushman Srivastava Ayush
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