February 6, 2010 at 5:12 pm
Comments posted to this topic are about the item Slowly Changing Dimensions
February 7, 2010 at 11:39 pm
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February 8, 2010 at 1:57 am
Type 1 Slowly Changing Dimension data warehouse architecture applies when no history is kept in the database. The new, changed data simply overwrites old entries. This approach is used quite often with data which change over the time and it is caused by correcting data quality errors (misspells, data consolidations, trimming spaces, language specific characters).
Type 1 SCD is easy to maintain and used mainly when losing the ability to track the old history is not an issue.
February 8, 2010 at 1:57 am
Slowly changing dimension Type 2 is a model where the whole history is stored in the database. An additional dimension record is created and the segmenting between the old record values and the new (current) value is easy to extract and the history is clear.
The fields 'effective date' and 'current indicator' are very often used in that dimension and the fact table usually stores dimension key and version number.
February 8, 2010 at 11:00 am
Nice question. Thanks
Jason...AKA CirqueDeSQLeil
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March 30, 2010 at 8:57 am
I look forward to Raju The Leader (???) enlightening us all about Type 3 SCDs :laugh:
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