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IBM Cognos Model Types

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by Ravindra Savaram
Last modified: July 2nd 2021

Cognos Model Types:

A model is a collection of metadata that includes physical information and business information for one or more data sources. (Have a quick glance at Define The Model In The Project)

There are 2 types of models defined in cognos10.1 BI

1)Relational model
2)DMR model (Dimensionally modeled relational source)

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1)Relational model:

  • A relational model created from the relational database as a source
  • A relational model supports Rolap and users cannot perform multi dimensional analysis such as drill up and drill down

A multi dimensional analysis is a technique to modify the data so that users can view the data at different levels of details

The following are the multidimensional techniques

a)Drill down: It is a process of navigating the data from highest level to lowest level details. A user can view the detailed information.

b)Drill up: It is a process of browsing the data from lowest level to highest level. A user can view the summary data.

2)DMR Model:

  • This model is created from a relational model as a source
  • A DMR model is created with the hierarchies
  • A hierarchy is an ordered series of related dimensions grouped together to perform multidimensional analysis
  • There should be one too many relationships between the levels
  • A DMR model is created with 2 types of dimensions

a)Regular Dimension
b)Measure Dimension

Regular Dimension:

A regular dimension contains descriptive and business key information and organizes the information in a hierarchy from the highest level of granularity to the lowest

  • It usually contains multiple levels
  • Each level requires KEY and CAPTION Hierarchies for regular dimensions:
  • A hierarchy is an ordered list of levels
  • A regular dimension is created with hierarchies

Following are the types of hierarchies:

1) Balanced hierarchy:

Each path in the balance hierarchy descends to the same depth.
Ex: The highest level is productline
       2nd level is the productype
       3rd level is the product

2) Unbalanced hierarchy:

The branches in the unbalanced hierarchy descend to different levels.
Ex: The highest level in the organization is the CEO.
       Level 2 is the vice president and CEO’s Executive Assistant.
The Vice Presidents have subordinates but Executive Assistants don’t have any subordinates.

Related Article: Cognos Interview Questions

3) Ragged Hierarchies:

At least one path in the hierarchy skips at least one level.
Ex: Highest level could be continent
       Level 2 is County
       Level 3 is a city
       Level 4 is street
A country such as Vatican city contains only streets no cities

4)Network hierarchies:

A member of the hierarchy has more than one parent

Levels for regular dimension:

  • A level is a collection of attributes typically of common granularity.
  • Each level needs an item that is defined as a KEY and another item that is defined as a CAPTION
  • The first level of the hierarchy is automatically defined as all level

Roles:

  • A role defines what appears in the member tree.
  • A role determines how to present the data to the users.

Regular dimension—     Hierarchy—     Levels—-     Attributes— Roles(Key,Caption)

Product(Regular Dimension)

Product(Hierarchy)

Measure Dimension:

Category(level 1)   

         Product_line_code(key)

         Product _lan_en(caption)

Subcategory(Level 2)

        Product_line_code(key)

        Product_type_en(caption)

Productname(Level 3)

       Product_number(key) 

       Product_name(caption)

       Product_description(Description)

It is defined as a collection of facts.

You can create a measure dimension for one or more query subjects that have a valid relationship between them.

Model measure dimensions should be composed of only quantitative items.

Ex: Key performance indicators like Sales, Net profit

Scope:

A scope defines a relationship between the regular dimension and the measure dimension.

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About Author

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NameRavindra Savaram
Author Bio

Ravindra Savaram is a Content Lead at Mindmajix.com. His passion lies in writing articles on the most popular IT platforms including Machine learning, DevOps, Data Science, Artificial Intelligence, RPA, Deep Learning, and so on. You can stay up to date on all these technologies by following him on LinkedIn and Twitter.