Vertical Slicing for a Data Warehouse (DW)/Business Intelligence (BI) Solution

There are several strategies that you can choose to employ with vertically slicing the requirements for a DW/BI solution. These strategies are described in the following table. There are example stories for each strategy as well as some advice for when to apply each strategy.

Table 1. Vertical slicing strategies for a DW/BI solution.

Slicing Strategy Example Stories When to Do This
One new data element from a single data source
  • As a Professor I would like to know the names of my students so that I know who should be there
  • As a Student I would like to know what courses are taught at the university
Very early days when you are still building out fundamental infrastructure components. Very common for the first iteration or two of Construction. These slices still add real business value, albeit minimal.
One new data element from several sources
  • As a Professor I would like the student list for a seminar that I teach
  • As a Student I would like to know what seminars are being taught this semester
Early days during Construction when you are still building out the infrastructure. These slices add some business value, often fleshing a DW data element to include the full range of data values for it.
A change to an existing report
  • As a Professor I would like to know the standard deviation of marks within a seminar that I teach
  • As a Student I would like to know how many spots are still available in a seminar
Evolution of existing functionality to support new decision making
A new report
  • As a Professor I would like to know the distribution curve of student marks in a seminar that I teach so I may adjust accordingly
  • As a Registrar I would like to know what Seminars are close to being full
Several iterations into Construction when the DW/BI solution has been built up sufficiently.
A new reporting view
  • As a Registrar I would like to know what the prerequisites are for a seminar so that I can advise students
  • As a Professor I would like to know the current course load of each student within a seminar that I teach
Several iterations into Construction when the DW/BI solution has been built up sufficiently.
A new DW/DM table
  • As a Chancellor I would like to track the revenues generated from parking pay meters to identify potential profits to divert to supporting students
  • As a Professor I would like to recommend suggested readings to help people prepare before taking a seminar
Several iterations into Construction when the DW/BI solution has been built up sufficiently.

There are several interesting things about the stories in the table:

  1. They are written from the point of view of your stakeholders. They aren’t a technical specification. For example, the first story describes how professors want a list of student names but it isn’t saying from what data source(s), what the element names are, … These are design issues, not requirement issues.
  2. They always provide business value. The first story appears to be the beginnings of an attendee list for a seminar. Having something as simple as a list of names does in fact provide a bit of value to professors.
  3. Sometimes that business value isn’t (yet) sufficient. It may take several iterations to implement something that your stakeholders want delivered into production, particularly at first. For example, although a list of student names is the beginnings of a class list it might not be enough functionality to justify putting it into production. Perhaps professors also need to know the program that the student is enrolled in, their current year of study, and basic information about the seminar such as the course name, time, and location of it. The decision as to whether the functionality is sufficient to ship is in the hands of your stakeholder (this is one of the reasons why you want to demo your work on a regular basis).

I’ve written a detailed explanation of vertical slicing for a DW/BI solution, and of course there is a wealth of information about agile database techniques in general for those of you interested in greater detail.  You may also find our one-day Disciplined Agile Data Warehousing/Business Intelligence Workshop to be a valuable learning experience too.

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