Tag archive for ‘Dimension Tables’
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Mystery or Junk data warehouse dimensions
Sometimes, when you are designing a star schema model, you'll find yourself in a dilemma. You've come up with a beautiful design, right out of the pages of a Ralph Kimball book with 5 dimensions, and 5 measures, and you are on your way to star schema heaven when suddenly the users start asking akward [...]
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Wolfram Alpha- Dimensional Generator?
Wolfram research is always doing some interesting things- and now they are aiming at providing an answer machine- they are calling it Wolfram Alpha. Its not a search engine that returns documents related to the inputed search terms- but something that computes answers to a question looking for a factual answer. This is interesting, because [...]
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Joining the Dimension Table to the Fact Table- Purchasing Data mart (Part 5)
After we have created the dimension tables and the fact table and populated them with data the final step to getting a star schema is of course to actually join the dimension tables to the fact table. In the datamartist tool we do this with a Join block. Check out the first four parts of [...]
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Connecting the dimension table to the fact table- Vendor Example (Part 3)
In parts one and two of this series we introduced our challenge (to make a data mart to analyze the Acme Company's spending) and showed how the Datamartist tool could import millions of rows of data and then turn it into a fact table we can use in Excel. Now we need to create a [...]
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Degenerate Dimensions in Datamarts
Not all dimensions are created equal. A typical dimension is defined by a table that holds the reference data that is being joined to the fact data. So in the fact table, for example, we have the product ID, or the product code, and in the product dimension table we have a single row for [...]
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Dimensional Tables and Fact Tables
One of the secrets to putting together a good set of data marts is the concept of dimensions. There are two key steps being able to analyse your data, and to build a working data mart model. Build a set of clean, consistent dimension tables that store reference information about your key dimensions like Product, [...]
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Data modelling Hierarchies- how to make a dimension
One of the most useful data model structures in a data mart is a Hierarchy (also called a Tree structure). Tree structures let us take a large number of things and organise them in a way that makes sense. More importantly, a tree structure lets us “drill down” into information. Hierarchy Rules In a simple tree [...]
