From: Yeb Havinga <yebhavinga@gmail.com>
To: Achilleas Mantzios <achill@matrix.gatewaynet.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Table Design for Hierarchical Data
Date: Thu, 08 Apr 2010 09:40:35 +0200
Message-ID: <4BBD8873.5040003@gmail.com> (raw)
In-Reply-To: <201004080956.06446.achill@matrix.gatewaynet.com>
References: <n2i5ab13581004061033j4ed25734xd0504cb95a1fc092@mail.gmail.com>
<201004071139.42140.achill@matrix.gatewaynet.com>
<4BBCEC03.3050100@gmail.com>
<201004080956.06446.achill@matrix.gatewaynet.com>
Achilleas Mantzios wrote:
> Στις Wednesday 07 April 2010 23:33:07 ο/η Yeb Havinga έγραψε:
>
>> Achilleas Mantzios wrote:
>>
>>> Στις Wednesday 07 April 2010 11:06:44 ο/η Yeb Havinga έγραψε:
>>>
>>>
>>>> Achilleas Mantzios wrote:
>>>>
>>>>
>>>>> You could also consider the genealogical approach, e.g.
>>>>>
>>>>>
>>>>> The parents of any node to the root, i.e. the path of any node to the root are depicted as
>>>>> parents[0] : immediate parent
>>>>> parents[1] : immediate parent of the above parent
>>>>>
>>>>>
>>>>>
>>>> What I have more than one parent?
>>>>
>>>>
>>> Then it is no longer neither a tree, nor a hierarchical structure, but rather a graph.
>>> This a totally different problem.
>>>
>>>
>> My question was actually an attempt to point at the inability of what
>> you call the 'genealogical approach' database design to store
>> information of more than one parent.
>>
>
>
> Are you suggesting that we should change our definition of trees ADT, just because it does not
> fit the mere detail that humans have two parents?
> Or are you just suggesting that the "genealogical" term is inaccurate?
>
The latter, but rethinking it, why would genealogical be a bad word when
applied to graph algorithm 'stuff' when words like parent, child,
ancestor, sibling are common use. When I read 'genealogical' I had only
the connotation 'family relations' in mind. I suspect that if looking at
the definition of the word genealogy alone, it could very well include
the study of single parent transitive relationships. However, not
exclusively, so yes, IMHO something called the genealogical approach
should not preclude polyhierarchies.
regards
Yeb Havinga
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Reply to all the recipients using the --to and --cc options:
reply via email
To: pgsql-sql@postgresql.org
Cc: yebhavinga@gmail.com, achill@matrix.gatewaynet.com
Subject: Re: Table Design for Hierarchical Data
In-Reply-To: <4BBD8873.5040003@gmail.com>
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
This inbox is served by DDX for PostgreSQL; see mirroring instructions
for how to clone and mirror all data and code used for this inbox