Comments on: Storing Hierarchical Data in a Relational Database http://blog.thefrontiergroup.com.au/2008/10/storing-hierarchical-data-in-a-relational-database/ Your peek inside the collective mind of The Frontier Group Tue, 08 May 2012 03:28:54 +0000 hourly 1 http://wordpress.org/?v=3.1.2 By: mlambie http://blog.thefrontiergroup.com.au/2008/10/storing-hierarchical-data-in-a-relational-database/comment-page-1/#comment-36 mlambie Fri, 31 Oct 2008 05:33:34 +0000 http://thefrontiergroup.com.au/blog/?p=117#comment-36 I'm using nested sets in a Rails application to represent a hierarchical menu system with great success. I used the <a href="http://agilewebdevelopment.com/plugins/awesome_nested_set" rel="nofollow">awesome_nested_sets</a> plugin. This plugin uses a parent_id along with lft and rgt so it's easy to traverse the tree top-to-bottom, as Mark suggested. I’m using nested sets in a Rails application to represent a hierarchical menu system with great success. I used the awesome_nested_sets plugin.

This plugin uses a parent_id along with lft and rgt so it’s easy to traverse the tree top-to-bottom, as Mark suggested.

]]> By: Mark W http://blog.thefrontiergroup.com.au/2008/10/storing-hierarchical-data-in-a-relational-database/comment-page-1/#comment-35 Mark W Fri, 31 Oct 2008 03:05:30 +0000 http://thefrontiergroup.com.au/blog/?p=117#comment-35 I read the same article a few months back when I was designing a schema for managing a hierarchy of climbing locations. The concern I had was that you need a very robust data access layer. Any corruption in your data could quickly break your entire tree. You can probably forget about running ad-hoc queries from the command line due to the added complexity. For any non-trivial application, I'd be tempted to additionally store parent references, so that the nested sets data could be rebuilt. It's frustrating that MySQL doesn't support hierarchical queries - a feature that has been in MS-SQL for several years and Oracle for significantly longer! I read the same article a few months back when I was designing a schema for managing a hierarchy of climbing locations. The concern I had was that you need a very robust data access layer. Any corruption in your data could quickly break your entire tree. You can probably forget about running ad-hoc queries from the command line due to the added complexity. For any non-trivial application, I’d be tempted to additionally store parent references, so that the nested sets data could be rebuilt.

It’s frustrating that MySQL doesn’t support hierarchical queries – a feature that has been in MS-SQL for several years and Oracle for significantly longer!

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