IT Answers » Data Warehouse Planning http://itknowledgeexchange.techtarget.com/itanswers Mon, 20 May 2013 00:58:28 +0000 en-US hourly 1 Pros & cons to have a typical star schema but with only one fact value field and a thousand attribute names in one of the dimension tables? http://itknowledgeexchange.techtarget.com/itanswers/pros-cons-to-have-a-typical-star-schema-but-with-only-one-fact-value-field-and-a-thousand-attribute-names-in-one-of-the-dimension-tables/ http://itknowledgeexchange.techtarget.com/itanswers/pros-cons-to-have-a-typical-star-schema-but-with-only-one-fact-value-field-and-a-thousand-attribute-names-in-one-of-the-dimension-tables/#comments Wed, 25 Nov 2009 12:07:30 +0000 Rwg Want to build a kind of a scientific fact search and analytical engine for a lot of different types of measurements hosted in a lot of source tables and columns.

A star join schema is built and data is copied (ETL) from the sources as usual – but all source column values are stored into a single fact-table value column and each column name is represented by a surrogate foreign key referencing a dimension table where the source table and column names are prestored.

There are several other dimensions as well, as usual. In this design ER-structures in the source database are deliberately abandoned, the only structure that is preserved is repeating groups through a simple serial number dimesion, so that e.g. time series values and depth intervals (stratigraphy) are chained. One might have a second fact value column for alphanumeric codes.

There will be a lot of rows in the fact table, but rather short ones. The star join database can be searched with SQL and simple statistics may be presented or one may take resulting datasets to other analytical tools, e.g. Excel. The SQL in queries may sometimes be tricky in this design. One might create (with SQL-scripts) smaller and specialized data marts on different topics from this data warehouse.

An interesting quality is that space coordinates in the fact table open up for unlimited possibilities to select and present data on digital maps from a GIS tool. 

/RWg, Geological Survey of Sweden.

]]> http://itknowledgeexchange.techtarget.com/itanswers/pros-cons-to-have-a-typical-star-schema-but-with-only-one-fact-value-field-and-a-thousand-attribute-names-in-one-of-the-dimension-tables/feed/ 2 Build a Data warehouse end to end http://itknowledgeexchange.techtarget.com/itanswers/build-a-dataware-end-to-end/ http://itknowledgeexchange.techtarget.com/itanswers/build-a-dataware-end-to-end/#comments Mon, 03 Aug 2009 12:39:51 +0000 Jsql Im asked to build a datawarehouse from end to end. I have already worked on datawarehousing projects. I need to prepare a proposal document.

How do i prepare a proposal document that explains End-to-end development. Can I get a sample document?

Thanks.

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