Database Administrators Stack Exchange
Database Administrators Stack Exchange

Questions tagged [dimensional-modeling]

96 questions
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Datawarehouse Design: Combined Date Time dimension vs. Separate Day and Time dimensions and timezones

We are just starting design for a new data warehouse and we're trying to design how our date and time dimensions will work. We need to be able to support multiple timezones (probably at least GMT, IST, PST and EST). We were initially thinking that…
Matt Palmerlee
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Dimensional Modeling and ETL in Redshift

I have been researching Amazon's Redshift database as a possible future replacement for our data warehouse. My experience has always been in using dimensional modeling and Ralph Kimball's methods, so it was a little weird to see that Redshift…
njkroes
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Is my understanding of Fact table granularity correct?

Myself and another DBA at our company are tasked with reviewing a database design that a vendor has developed for us. The vendor has said they use Kimball as the basis for their design. (NOTE: I am not looking for arguments of Kimball vs Inmon,…
Chris Aldrich
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Designing a dimensional DB off a normalized source that already implements SCD's

I have built an SSIS ETL to integrate various data sources (one from MySQL, two from SQL Server) into a single SQL Server relational and normalized database, which I've called [NDS]. The SSIS ETL handles type-2 updates, and so the [NDS] generates…
Mathieu Guindon
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What is the difference between bridge table and helper table in data warehouse's context?

From what I could understand :- Bridge tables are used when a dimension table can not be directly associated with a fact table. e.g. In a bank's data warehouse a fact table of balance of a customer can't be stored with a customer ID as link between…
aarushi
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If a DW fact table is not uniquely identified by all dimensions, what problems?

This is a bit of a thought problem I've been wrestling with. I have a visceral antipathy to the notion of duplicate combinations of dimension values in a fact table. I've read a lot about the existence of problems when the combination of…
Andrew Wolfe
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What are the difference between a "dimension" table in a star-schema and a "lookup" table in a relational database?

I'm trying to design a star-schema fact table along with some dimension tables that will surround it. If I reuse the natural key called customer_key in both the fact_table and dim_customer then I don't see a difference between calling something dim…
Krolique
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Cube with 2 measure groups (with different relationships to dimensions) returns too many dimension members in reports

I have a cube that contains stock-take data from retail operations. It has 2 measure groups - one containing the number of stock units counted in each stock-take batch (which is related to the Product, Batch and Time dimensions), and another…
Laurence
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what is the difference between 'order' and 'order line'?

I was trying to understand degenerate dimensions. But I quite often encounters the term "order line" as grain in an transaction table. Could someone please explain the difference between the order and order-line ?
Arpit Agrawal
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Boolean as measure in fact table or dimension/attribute value

My fact table consists of complaints with typical dimensions of who, what and when. We have a target that the complaint should be responded to within a certain time period. I'm not sure on how I best to model whether the complaint had a response…
mhep
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How do I make a nullable "parent" hierarchy level?

I'm setting up my first dimensional database with SSAS, and I have this [Materials] dimension that needs a hierarchy that goes something like this: [PriceCode v] --> nullable Price Code ... [Material v] Code AltCode Name ... [Id …
Mathieu Guindon
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How can I get the measures of the last month with MDX?

I would like to get the values of the measures of the previous month. That's what I have: SELECT [Measures].[Recuent distinct] ON ROWS, TAIL(NonEmptyCrossJoin([Dim Date].[Calendar].[Month Name].Members,1),1) ON COLUMNS FROM [BDID] …
Miguel
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When to choose an attribute vs. a new dimension?

I am fully aware of what is a fact, attribute and dimension. However, I'm quite confused to which traits I should choose for dimensions vs attributes of that dimension. For instance, I'm building a hospital data warehouse and gender could be a…
LearnByReading
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To normalize or not to normalize for few distinct values

Assuming in a Postgres database, you have a table called party, which can have less than 5 well-defined party_types such as 'Person' or 'Organization'. Would you store the party_type in the party table (e.g. party_type = 'Person') or normalize it…
Mike81
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Store email in a separate Dimension or in a Degenerate Dimension?

I just started learning about dimensional modeling and I am creating a star to analyse email newsletter signups for an online business. I have a fact table that records the signups and links to a contact dimension, traffic source dimension, page…
user3505886
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