From: Achilleas Mantzios <achill@matrix.gatewaynet.com>
Organization: Dynacom Tankers Mgmt
To: pgsql-sql@postgresql.org
Subject: Re: Table Design for Hierarchical Data
Date: Mon, 12 Apr 2010 10:14:09 +0200
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=CE=A3=CF=84=CE=B9=CF=82 Thursday 08 April 2010 17:59:01 =CE=BF/=CE=B7 Rob =
Sargent =CE=AD=CE=B3=CF=81=CE=B1=CF=88=CE=B5:
> 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.
>=20
> On 04/08/2010 12:56 AM, Achilleas Mantzios wrote:
> > =CE=A3=CF=84=CE=B9=CF=82 Wednesday 07 April 2010 23:33:07 =CE=BF/=CE=B7=
 Yeb Havinga =CE=AD=CE=B3=CF=81=CE=B1=CF=88=CE=B5:
> >> Achilleas Mantzios wrote:
> >>> =CE=A3=CF=84=CE=B9=CF=82 Wednesday 07 April 2010 11:06:44 =CE=BF/=CE=
=B7 Yeb Havinga =CE=AD=CE=B3=CF=81=CE=B1=CF=88=CE=B5:
> >>>  =20
> >>>> Achilleas Mantzios wrote:
> >>>>    =20
> >>>>> 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 t=
he root are depicted as
> >>>>> parents[0] : immediate parent
> >>>>> parents[1] : immediate parent of the above parent
> >>>>>  =20
> >>>>>      =20
> >>>> What I have more than one parent?
> >>>>    =20
> >>>
> >>> Then it is no longer neither a tree, nor a hierarchical structure, bu=
t rather a graph.
> >>> This a totally different problem.
> >>>  =20
> >> My question was actually an attempt to point at the inability of what=
=20
> >> you call the 'genealogical approach' database design to store=20
> >> information of more than one parent.
> >=20
> >=20
> > Are you suggesting that we should change our definition of trees ADT, j=
ust because it does not
> > fit the mere detail that humans have two parents?
> > Or are you just suggesting that the "genealogical" term is inaccurate?
> >=20
> > Take a look here: www.tetilab.com/roberto/pgsql/postgres-trees.pdf
> >=20
> >>
> >> regards,
> >> Yeb Havinga
> >>
> >>
> >=20
> >=20
> >=20
>=20


=2D-=20
Achilleas Mantzios