Questions tagged [dimensional-modeling]

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In the practice of Kimball's Dimensional data warehouse design model, do lookup tables (not dimensions) contain a sid column?

Trying to create a simple lookup table for a drop down on a BI web page. The table contains 2 columns, an key and a description. What is the best practice with regard to Dimensional Modeling when ...
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50 views

Cascading One-to-Many relationships modeling

Are there any drawbacks or better alternatives of this non relational model ? I note that it remains easy to understand but the concern is with the code interacting with. First, as I was introduced ...
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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 ...
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1answer
42 views

Database model / design best practice

I'm looking for a some guidance/advice on how to best model my data. Some background: I have location information that I'm trying to model. There are two categories of locations (company and non-...
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14 views

How does one determine the number of FACT tables that are required in a data-warehouse? [closed]

When analysing data sources that need to be included in the data-warehouse (Kimball), how does a developer determine whether a schema should be a star type or constellation type? Business processes ...
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1answer
85 views

How to optimally structure a table with sparse data

I am working on a project to create a series of tables that are easier to use and more intuitive for fairly naive SQL users. Because of the structure of our data, we are running into a trade-off ...
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5 views

Unconventional Fact Table - general event type with different event sub-types in one table

I am working on a DW project and currently beginning preliminary modeling. The core raw data I am beginning with isn't so much like the classic DM example cases of sales with dollar values, etc. I ...
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13 views

Dimensional Modeling in Redshift - How wide to go?

I am playing with Redshift as a solution for a data warehouse I am architecting and I am trying to get my head around best practices for dimensional modeling in this case. I am using one source ...
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1answer
31 views

Implementing a degenerate dimension with an alphanumeric varchar(30) at the transaction level?

I am currently working on designing my first data model and I am confused about this particular implementation of degenerate dimensions. According to Kimball's design tip 46, a degenerate dimension ...
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40 views

Dimension attribute with one-to-many relationship

I have a request for an attribute in a dimension that has a one-to-many relationship with the lower level of the dimension. Here is the case: Dimension: Employee Attribute: Immatriculation I have ...
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1answer
18 views

How to model changing OrderLine rows in fact table

In our business, we have Orders that are made up of OrderItems. Over time, these Orders can change status (e.g. Received, Challenged, Planned, Completed). During this process, the OrderItems for an ...
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12 views

Rolling up/aggregating a duration measure in OrderLine fact table

I am starting to model a datawarehouse, and would like some suggestions. We have Orders and OrderLines. I have read that it is often recommended to model this as one OrderLine fact table at the ...
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1answer
39 views

What is the meaning of “dimension key”?

I am a beginner trying to understand the basic concepts of database's. I know several types of keys (Primary key, Foreign key, candidate key, super key, surrogate key.....etc). While learning about ...
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1answer
463 views

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 ...
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1answer
143 views

Data Warehouse Modeling: Sales Order Charges [closed]

I have two databases systems that I'm trying to dimensional model a sales order business. Both operational data stores have a Sales Order header and detail table. However, one of them has an ...
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0answers
112 views

Dimensional Model for CRM Sales Opportunity and Sales Leads: Fact or Dimension?

I'm working for a business lender, and trying to come up with a basic dimensional model around the subject area of loan approvals. We use a CRM, (Salesforce) and one of the core objects is a (Sales) ...
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1answer
236 views

Dimensional Modeling of a Loan Approval Process and Fact Grain(s)

Context: I'm modeling for a lending company and I'm modeling our loan approval process. I have some basic dimensions relative to our business figured out: Time(day) Account Opportunity ...
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0answers
15 views

Fact Grain & Modeling Loan Approval Proccess [duplicate]

I'm modeling for a lending company and I'm modeling our loan approval process. I have some basic dimensions relative to our business figured out: Time(day) Account Opportunity Channel And I and ...
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1answer
318 views

How to normalize CSV invoice data?

For flat data which comes in with fields like: name address status class version user mode CSV files are regularly received, with the above as typical columns. ...
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1answer
118 views

Can multiple fact tables have the same structure? [closed]

I'm designing the schema of a data base and I have two solutions : the first is to use one fact table linked to multiple dimensions. the second is to use multiple fact tables with same structure for ...
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50 views

How to Represent a VARCHAR Column with XML Data in a Fact Table?

I have SQL Server 2016 environment and I have decided to design a source table with holds some sort of event data as a transactional fact table. The table has about a million rows, and generates about ...
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2answers
200 views

What is the industry term for superset of “metrics” and “dimensions”? [closed]

If I want to refer to measures/metrics and dimensions with a single term, what would be a good industry-accepted expression? Metrics is used commonly in UIs as well such as Google Analytics or ...
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0answers
503 views

Kimball Cross Reference Table/Bridge Table

I'm currently struggling to understand how to apply Kimball methodology to a certain scenario and talk of Outriggers/Cross Reference/Bridge tables are starting to get confusing. Consider the scenario:...
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1answer
64 views

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 ...
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0answers
143 views

Are there differences between a Fact Constellation Schema and a Galaxy Schema?

I am currently working on the two schemes and I'm just not sure if they are the same or if there are differences. In the literature both are often synonymous. Now I've read that there are differences (...
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2answers
82 views

Is there a recommended order to create a DV model and star schema?

I want to create and implement a Data Vault Model. In the presentation layer, I want to create a View based on a star schema. Now I would like to know if there is a certain order in creating the ...
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2answers
147 views

Should I use separate address dimensions?

I have a Star Schema model with two Dimensions (User and Store) each of them have addresses, which I store. Each User and Store can just have one Address. Is it recommended to split the Dimension ...
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2answers
3k views

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'...
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2answers
701 views

Dealing with different types in a fact table

I'm working with dimensional modelling for the first time, trying to build a data warehouse that pulls in data from an OLTP database, and I'm having some trouble figuring out what to do with this type ...
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0answers
167 views

Permission error while browsing the Dimension when Dimension Security is defined on one of the attribute

I am using SSAS SQL Server for dimension modelling, and the dimension is defined as below: Dimension Name: Department Dimension Attributes: Location DepartmentCode DepartmentType I have ...
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3answers
465 views

Should a Fact table contain a column with a single unique value?

In order to simplify reporting, I am wondering if for each of the Fact tables we have, whether I can include a column that states the name of the Fact table, albeit in a more user friendly format e.g....
4
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1answer
1k views

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 ...
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3answers
1k views

Should dates in dimensional tables use dimDate?

Assuming my dimDate has a surrogate key. Should all the date columns in the dimensional tables (not the fact tables) store the surrogate key of date dimension? Or just plain date? For example, in ...
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1answer
579 views

Periodic snapshot fact table with monthly grain - Question on dimensions

I am fairly new to data-warehousing but have read my fair share of books and online tutorials to gain an introductory understanding of the basic components that build up a data warehouse. My end goal ...
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0answers
87 views

When to Converge Dimensions in a Data Warehouse When There Are Few Common Attributes

I have two StudentDetails dimension tables in my data warehouse and I want to know whether I should converge them, considering that they have limited attributes in common (keeping in mind Kimball DW ...
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1answer
135 views

Dimension Modelling Senario Data Warehouse Design

I'm looking for some advised on how to model the following scenario in our data warehouse. We have the following entities Staff Mobile Devices Computers Mobile Bills If feels like its simpler to ...
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2answers
2k views

Best way to capture historical changes between levels in a dimensional hierarchy

What is the cleanest way to capture changes between levels in a dimensional hierarchy? I have the dimensional hierarchy [Area] > [Region] > [Location], where Area is the parent to Region and Region ...
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1answer
2k views

SSAS Hierachies duplicates when browsing

The dimensions in the cube are giving us duplicates, there is no error while processing the cube, but when the cube is browsed we could see duplicates. There is a hierarchy in our dimension, the ...
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1answer
671 views

SSAS MD dimension joins to same table twice (but processing fails as attribute has 2 names for same ID)

My cube has a product dimension, and each product has an "availability" status attribute. In the database, SellableItemAvailabilityId in DimSellableItemVersion (which contains products) joins to Id in ...
4
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2answers
4k views

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,...
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2answers
512 views

Ordering of a dimension in sql server datawarehouse

Built and deployed a simple cube with a date dimension. The dimension has things like day of month. How do i sort it? it always shows in the reports as 1, 10, 11, 12, ... 19, 2, 20, 21 Design. ...
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1answer
43 views

What if the lowest granularity level can legitimately be null?

I have a normalized database that I'm going to be using as a source for a dimensional data store; one of the facts I'm collecting is Orders, the normalized schema looks roughly like this: However ...
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1answer
264 views

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 ...
4
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1answer
370 views

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 ... ...
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1answer
7k views

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 ...
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2answers
1k views

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 ...
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0answers
130 views

Column Store Indices versus Dimensional Tables

I have a Data Warehouse and want to think ahead one year when I may get a database update allowing me to use column store indices. My dimensional tables are mostly junk dimensions containing columns ...
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1answer
169 views

Duration measure in fact table

I have a fact table with the user reservations with StartDate and EndDate. I am thinking what is the proper way of serving the duration queries in the reports. Should I calculate DurationDays and ...
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2answers
277 views

Dimensional Model for inheritance in dimensions

How are dimensions typically modeled in a dimensional model if one dimension logically inherits from another dimension? For example, assume I have an Employee dimension and a Driver dimension, where ...
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0answers
379 views

ETL flow in Fact tables

I've got a simple theoretical question... If we discuss the principles, elements, design and implementation of a typical ETL flow for a dimension table then, in my understanding, (in short) I'd say ...