From: Achilleas Mantzios <achill@matrix.gatewaynet.com>
To: pgsql-sql@postgresql.org
Subject: Re: Table Design for Hierarchical Data
Date: Mon, 12 Apr 2010 10:14:09 +0200
Message-ID: <201004121114.10189.achill@matrix.gatewaynet.com> (raw)
In-Reply-To: <4BBDEF35.6040308@gmail.com>
References: <n2i5ab13581004061033j4ed25734xd0504cb95a1fc092@mail.gmail.com>
<201004080956.06446.achill@matrix.gatewaynet.com>
<4BBDEF35.6040308@gmail.com>
Στις Thursday 08 April 2010 17:59:01 ο/η Rob Sargent έγραψε:
> The "parent" node in a genealogy is the mother-father tuple, so given
> that as a singularity it still fits a tree.
No, because the child and parent node would be of different schema.
>
> On 04/08/2010 12:56 AM, 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?
> >
> > Take a look here: www.tetilab.com/roberto/pgsql/postgres-trees.pdf
> >
> >>
> >> regards,
> >> Yeb Havinga
> >>
> >>
> >
> >
> >
>
--
Achilleas Mantzios
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: achill@matrix.gatewaynet.com
Subject: Re: Table Design for Hierarchical Data
In-Reply-To: <201004121114.10189.achill@matrix.gatewaynet.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