Dimensions in data management and data warehousing contain relatively static data about such entities as geographical locations, customers, or products. A data modeler must plan for conformance in their design by ensuring that key dimensions of the enterprise are conformed dimensions that can be expanded to include new attributes over time. The calendar date dimension has some very unusual properties. Hi there! Dimensional models that lack conformed dimensions will only be able to answer simple questions for the particular data mart for which the dimension was built. I’ve tried DATENAME(ww, @FiscalCounter) but it doesn’t work as it doesn’t handle end of months properly. -- Hold our dates, -- Holds a flag so we can determine if the date is the last day of month, -- Number of months to add to the date to get the current Fiscal date. Measurements are defined at specific points of time and most measurements are repeated over time. PS. Change ), You are commenting using your Facebook account. In this simple example. -- If the begin date is after the end date, no errors occur but nothing I’m a big fan of the Kimball method of Data Warehousing. -- These two counters are used in our loop. Change ), You are commenting using your Twitter account. Other dimensions are often populated from imperfect source systems, including the least perfect of all: the spreadsheet. -- happens as the while loop never executes. , NULL Commonly used dimensions are people, products, place and time.. (Note: People and time sometimes are not modeled as dimensions). The Audit dimension keeps track of each execution branch of your Integration Services packages. The Date Type attribute almost always has the value “date” but there must be at least one record that handles the special non-applicable date situation where the recorded date is inapplicable, corrupted, or hasn’t happened yet. The date dimension hierarchies are easy to load and maintain. sysobjects WHERE id = OBJECT_ID ( N '[Dim]. An excellent article – and this code is just the sort of thing I was looking for! Holidays, work days, fiscal periods, week numbers, last day of month flags, and other navigational attributes must be embedded in the calendar date dimension and all date navigation should be implemented in applications by using the dimensional attributes. -- Set the date to start populating and end populating. Ralph Kimball (born 1944) is an author on the subject of data warehousing and business intelligence.He is one of the original architects of data warehousing and is known for long-term convictions that data warehouses must be designed to be understandable and fast. Slowly changing dimensions are used when you wish to capture the changing data within the dimension over time. It also doesn’t have a conventional source. For the inapplicable date case, the value of the Date Type is “inapplicable” or “NA”. However, what happen if the lowest grain of certain fact are at date level? In stage_2, after researching online the examples I noticed they all used a separate date/calendar dimension table. -- begins July 1, put a 6 there. , NULL Also, unlike the calendar day dimension, there are very few descriptive attributes for the specific minute or second within a day. Kimball’s Step 3: Identify the dimensions Next we identify the dimensions, but don’t take the enterprise bus matrix’s word for it. However as with all smart keys, the few special records in the calendar date dimension will make the designer play tricks with the smart key. More about the Kimball Group Reader (Kimball/Ross, 2016), Advanced Dimension Patterns & Case Studies, Design Tip #51: Latest Thinking On Time Dimension Tables. Ralph Kimball founded the Kimball Group. Otherwise I use scripts but my new experience tells me that I might actually go Kimball spreadsheet . Also, what was the point of inserting a single row filled with nulls and ‘unknowns’? Spreadsheets were developed as computerized analogs of paper accounting worksheets. The Data Warehouse Toolkit established an extensive portfolio of dimensional techniques and vocabulary, including conformed dimensions, slowly changing dimensions, junk dimensions, mini-dimensions, bridge tables, periodic and accumulating snapshot fact tables, and the list goes on. In it he mentioned using Dim and Fact schemas, thus you’d have [Dim]. The best way to generate the calendar date dimension is to spend an afternoon with a spreadsheet and build it by hand. It is one of the only dimensions that is completely specified at the beginning of the data warehouse project. The Full Date attribute is a full relational date stamp, and it takes on the legitimate value of null for the special cases described above. Here we are presented with a list of the columns in the Customer dimension with the accompanying descriptions entered into the Kimball Requirements Spreadsheet as well as the data type which was pulled directly out of the SQL Server Catalog. Thanks fella, very useful. Ralph Kimball and Margy Ross co-authored the third edition of Ralph’s classic guide to dimensional modeling. We give all the properties of the database in the workbook and use a macro to generate the script based on the given properties. Code Sample 2 – Modified Kimball code to create a Date dimension. In their book, “The Microsoft Data Warehouse Toolkit With SQL Server 2005 and the Microsoft Business Intelligence Toolset”, they have an example of a good date dimension table in their books sample code. /* Loads a Date Dimension */ It is one of the only dimensions that is completely specified at the beginning of the data warehouse project. Thanks. be null. Virtually every fact table has one or more time related dimension foreign keys. [Date]' ) AND OBJECTPROPERTY ( id , N 'IsUserTable' ) = 1 ) … There are a lot of misconceptions about dimensional modeling and the Kimball approach to building a DW/BI system. I understood Kimball way of implementation Date Dimension table. ( Log Out / Because the DateKey is uniquely indexed, Good catch, fixed the posted code. I’m a big fan of the Kimball method of Data Warehousing. Ralph Kimball is the founder of the Kimball Group and Kimball University where he has taught data warehouse design to more than 10,000 students. Unknown is a catch all for all 3 of these situations. – Product Code is not found during lookup (use -1 and then someone will realise that Marketing forgot to tell you about the new promotion code for a product) – the FACT rows still load but rollup under “Invalid” for the Product Name Thanks -- A few notes, this code does nothing to the existing table, no deletes Ralph Kimball and Margy Ross co-authored The Data Warehouse Toolkit, Third Edition (Wiley, 2013). Kimball Dimensional Data Warehouse Course Gathering Requirements and Designing a Data Warehouse How do you gather requirements for a Data Warehouse/Business Intelligence project? Type 1 – For this type of slowly changing dimension you simply overwrite the existing data values with new data values. In a data warehouse, dimensions provide structured labeling information to otherwise unordered numeric measures. Conclusion. [Date] instead of [dbo].[DimDate]. /* Make sure the Dim schema exists */ IF SCHEMA_ID ( 'Dim' ) IS NULL EXECUTE ( 'CREATE SCHEMA [Dim] AUTHORIZATION [dbo]' ) GO /* Drop table DimDate */ IF EXISTS ( SELECT * FROM dbo . We are living in the age of a data revolution, and more corporations are realizing that to lead—or in some cases, to survive—they need to harness their data wealth effectively. Fill in your details below or click an icon to log in: You are commenting using your WordPress.com account. Data captured by Slowly Changing Dimensions (SCDs) change slowly but unpredictably, rather than according to a regular schedule.. ( Log Out / I liked the idea as it was something I’d been considering myself, so in this version that is what I did. I’m still pretty green to SSAS/Kimball, but the approach (create in Excel, load to SQL) I used was a major pain in the posterior. Kimball-based data warehouses can be set up quickly. Ralph Kimball, PhD, is well known as the father of dimensional data modeling. A T-SQL solution was clearly, to me anyway, the superior answer for both ease of use and long term stability. Made the change to replace the static date with @DateCounter. The best way to do this when your source data is in a relational database is to With significant amounts of new and updated material, The Data Warehouse Lifecycle Toolkit, 2nd Edition will set the standard for DW/BI system design and development for the next decade. Below is the fruit of my labor, a script for loading a Kimball like date dimension. Thanks but check your code before posting (I have an intense dislike for debugging other people’s code!) -- the beginning of the Fiscal year. One final, but very important distinction. Finally quite often it’s a DBA setting up the warehouse, and I’ve found there are still a few DBAs who are uncomfortable relying on SSIS, although I’m happy to say that number continues to shrink. Thanks for the really useful post Arcanecode. I did find some code for loading some very simple date dimensions, but nothing as complete as the Kimball design. They used an Excel spreadsheet, then a SQL Server Integration Services package to read the Excel file and load the date dimension table. Change ), You are commenting using your Google account. -- the current date in the loop, -- add a record into the date dimension table for this date, ) MARGY ROSS is President of DecisionWorks Consulting and the coauthor of five Toolkit books with Ralph Kimball. Great article and the sample code was very helpful. -- Set this to the number of months to add to the current date to get This is great code! Nothing is more predictable than the calendar, and no user intervention is required. Double-click the Sheet1 tab and change the name to Totals . Complex real-world case studies the lowest granularity date represent each record, with the granularity of a single.. 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