Tag Archives: Dimensional Modelling

Blogging Whilst Employed – Beware!

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Creative Commons License photo credit: eshm
I was having a flick through my employment contract and I found the following clause:

13.2
You agree that during the course of this contract and after the termination of the contract for whatever reason without limit in point in time you will keep in confidence and shall not disclose to any person unless authorised to do so with the prior written consent of the Company the following:-
13.2.1 Any consultancy know-how, methods, tools, techniques or intellectual capital.

I realised that some of my blog entries or tweets could fall foul of this clause so I asked for written permission to continue blogging generic “work related” content such as Business Intelligence, Data Warehousing, Data Modelling and Business Objects.
Rather than granting this and leveraging the fairly good google rankings that my posts seem to get I was asked to remove all work related posts.
Business Objects Best Practice (higher ranking than BusinessObjects.com)
Business Objects New Features (Page One)
Dimensional Modelling (Ralph Kimball ?)
As such I have password protected all of my work related posts.
If you are struggling to find content there are a variety of searches that could turn up interesting content.
Alternatively you can go to my company site, contact details can be found here or here.

Dimensional Modelling – Facts


Creative Commons License photo credit: Felipe Morin

I am often asked by my colleagues to explain dimensional modelling concepts to them. I will try to capture come on the concepts here. I am going to focus on Facts.

Specifically, types of facts: Accumulating, Factless, Transactions, Snapshots, Additive, SemiAdditive and Non Additive

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Dimensionally Modelling A Recursive Hierarchy


Creative Commons License photo credit: gadl

I was recently asked how to include a recursive hierarchy into a dimensional model.

What do I mean by a recursive hierarchy? This is when an entity (a table) relates to it’s self. Take the following example from an Oracle database:

EMPNO ENAME JOB MGR HIREDATE SAL COMM DEPTNO
7369 ‘SMITH’ ‘CLERK’ 7902 ’17-DEC-1980′ 800 NULL 20
7499 ‘ALLEN’ ‘SALESMAN’ 7698 ’20-FEB-1981′ 1600 300 30
7521 ‘WARD’ ‘SALESMAN’ 7698 ’22-FEB-1981′ 1250 500 30
7566 ‘JONES’ ‘MANAGER’ 7839 ‘2-APR-1981′ 2975 NULL 20
7654 ‘MARTIN’ ‘SALESMAN’ 7698 ’28-SEP-1981′ 1250 1400 30
7698 ‘BLAKE’ ‘MANAGER’ 7839 ‘1-MAY-1981′ 2850 NULL 30
7782 ‘CLARK’ ‘MANAGER’ 7839 ‘9-JUN-1981′ 2450 NULL 10
7788 ‘SCOTT’ ‘ANALYST’ 7566 ’09-DEC-1982′ 3000 NULL 20
7839 ‘KING’ ‘PRESIDENT’ NULL ’17-NOV-1981′ 5000 NULL 10
7844 ‘TURNER’ ‘SALESMAN’ 7698 ‘8-SEP-1981′ 1500 0 30
7876 ‘ADAMS’ ‘CLERK’ 7788 ’12-JAN-1983′ 1100 NULL 20
7900 ‘JAMES’ ‘CLERK’ 7698 ‘3-DEC-1981′ 950 NULL 30
7902 ‘FORD’ ‘ANALYST’ 7566 ‘3-DEC-1981′ 3000 NULL 20
7934 ‘MILLER’ ‘CLERK’ 7782 ’23-JAN-1982′ 1300 NULL 10

From this we can see that there is a recursive hierarchy within this table between the empno column and the mgr column, the mgr column shows the employee that is the manager for each row.
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