Re: estimate a DWH project

Hi Herman!


> Hi folks,
> does someone has a guideline to roughly estimate how long the
> development of a dwh can be (in weeks) ??
> Some possible factors:
> the number of inflow files, fact tables, dimension tables and the
> variables in these tables..
> how many olap cubes, ...

Are you looking for a closed formula, giving you the time
needed/estimated to complete a data warehousing project
given the parameters you quoted above? If yes, such a
formula doesn't and can't exist.

The only way to get an estimate, is to hire an experienced
Project Manager for data warehousing, who will analyze
your requirements and calculate/estimate the total effort.

Still, to give you an idea of the life cycle, here is a list
of some major phases for a typical DW project:

- project management (on-going)
- collecting business requirements
- defining the dimensional model
- defining architecture for the back room
- defining architecture for the front room
- defining the security model
- physical model
- ETL design and development
- client applications design and development


A Project Manager for data warehousing will decompose
each of those phases into a corresponding WBS (Work
Breakdown Structure), that is, into subtasks and estimate
effort (measured in "staff day" units) for each of those
subtasks.

Finally, he will roll up all efforts for the most detailed subtasks
and calculate the total effort for the project.


Example (ER = Effort Eemaining):


       [ 10%]...Sämtliche DW Arbeit...ER: 207 staff day
              [100%]...Phase 0 (Vorführung/Demo)...ER: none (completed).
              [ 93%]...Phase 1 (Projekt Definition)...ER: 1 staff day
                     [100%]...Preliminary Scope...ER: none (completed).
                     [100%]...Build Business Justification...ER: none
(completed).
                     [100%]...Establish Project Identity...ER: none
(completed).
                     [100%]...Staff the Project...ER: none (completed).
                     [100%]...Develop initial schedule and WBS...ER: none
(completed).
                     [100%]...Develop communications plan...ER: none
(completed).
                     [  0%]...Project team kick-off meeting...ER: 1 staff
day
              [ 50%]...Phase 2: Technologie Definition...ER: 1 staff day
                     [100%]...Design der Arhitektur...ER: none (completed).
                     [  0%]...Produktauswahl und Installation...ER: 1 staff
day
       etc.

--
HTH, Sven
---
http://www.svenkolar.net