Comments on: Handling Recursive Hierarchies in SQL Server

By: BI Monkey

BI Monkey — Thu, 20 Oct 2011 01:05:26 +0000

Sorry Gary, I rarely touch Oracle so don’t have a translated version available.

By: Gary

Gary — Wed, 12 Oct 2011 12:20:38 +0000

I am using the Kimball Helper Table Method perfectly against a SQL-Server database. The only problem is I am now having to port to and Oracle 10(something) database.

The code does not work in this environment, so I wondered if you had Oracle equivalent code available?

If yes I would greatly appreciate a copy.

By: Mike

Mike — Thu, 17 Mar 2011 19:48:44 +0000

The problem with the LR Method, otherwise known as Nested Sets, is inserting, deleting and moving nodes to other parents. When you do one of these things, you have to update all the left and right nodes to compensate for the change. If you’ve put indexes on your Left and Right columns (to improve query performance) and you update a node in a tree with hundreds of thousands of records, you may need to write tens of thousands of updates to left and right columns when you change just one node.

So, Nested Sets may be good for a content publishing system where updates don’t need to happen in real time, but it’s not ideal for an active web application, especially a distributed one, where reaction time is important.

By: Brett

Brett — Fri, 05 Nov 2010 16:03:21 +0000

Your solution helped me tremendously! I was trying to avoid some large recursive queries. Thanks!!!

By: Brenda Brink

Brenda Brink — Wed, 26 May 2010 13:54:59 +0000

I don’t understand Fig. 7 in your example. Kimball’s article says that the depth from parent counts how many levels the subsidiary is below the parent. For example, it seems that DFP for A1-A4 should be 2, not 1, and for A6-A6 should be 0, not 2. What am I missing?

By: BI Monkey

BI Monkey — Wed, 28 Apr 2010 20:24:18 +0000

The scripts here aren’t able to cope with that. From a dimensional perspective it then becomes a design decision about how you handle such cases. Can you support multiple hierarchies for example? Or set up a scenario where data is duplicated to handle each parent? Not easy!

By: la

la — Wed, 28 Apr 2010 13:27:28 +0000

what happens to the sum when a node has multiple parent ?

By: BI Monkey

BI Monkey — Sun, 18 Apr 2010 07:28:13 +0000

As in the example, just use Count instead of Sum – too easy

By: SRB1

SRB1 — Sat, 17 Apr 2010 16:51:01 +0000

Please, show ho to get the number of children for each parent.

By: BI Monkey

BI Monkey — Wed, 24 Feb 2010 00:41:37 +0000

RHD110, i’m not 100% sure I follow but this is my understanding:

1) Each assembly can have a sub-assembly
2) Each assembly can have multiple items

The issue you have is that because each assembly can have multiple items you cannot simply express the items as a property of the assembly.

I can see a couple of options for the display of this, depending on what suits your business needs:

1) Have an Assembly hierachy which is separate from your item dimension or
2) Treat each Assemblys items as part of the Assembly hierarchy, and indicate that an Item is not strictly part of the assembly hierarchy (e.g. with a prefix on the member name)

Cheers, James