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Subject: Permaculture Database

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  • From: jedd <jedd@progsoc.org>
  • To: pcdb <pcdb@lists.ibiblio.org>
  • Subject: Re: [pcdb] I'm interested in some contribution to
  • Date: Fri, 27 Mar 2009 18:56:02 +0000

On Fri Mar 20 2009, Paul d'Aoust wrote:
> Sometimes, when I wake up in the morning, the first thought in my
> head will be 'PCDB!' and my mind will start racing about how to
> construct entity relationships that are flexible enough to model
> everything from actinomycetes to lakes to chickens to exotic hand
> tools, yet structured enough to have useful searches performed on
> them... it's tough work, as I think we all discovered. I don't know
> how many E-R diagrams I've scribbled out on pieces of paper that I've
> subsequently lost.

Okay - an easy question to follow from this.

I have an organism table - it contains the taxonomy references,
amongst other things, and is tied against 20+ taxa tables. But
it'll work I think.

I'm currently stuck on two things.

The first is non-organisms. Apart from coming up with a word to
describe everything that isn't an organism, and debating whether
to make organisms a subset of a bigger category, is the question
of whether to break them up into certain categories again, or
try to keep them totally abstract - ie, to cover everything that
isn't alive.

I'm thinking of things here like soil (types), mulch, light/shade,
water, irrigation pipe, sheds, tools, fertilisers, etc.


The second thing is relationships. I want to be able to define a
relationship between any two things - organic or otherwise - and
so I'm trying to keep this abstract, flexible, and useful. At the
moment I'm thinking that I need to cover two broad aspects of
the relationship between items. First, structural - that one item
is a subset of another. This is relatively straightforward by a
component_of table that just has parent and child FK's back to
the organism/non-organism tables. The second is the harder
one, and concerns the type, or degree, or quality of the relationship.

I'm thinking of things like 'provides', 'requires', 'works with',
'dislikes', 'prevents' - as the direction or quality of the relation,
and then perhaps a -10 to +10 quantity to assign to that
relationship. I have (yet another) sub-problem handling whether
that degree or quantity should be variant based upon a use or
other factors (soil types, climate, site, aspect, etc).

So .. where did you get up to with this stuff? Did you head down
this mental path already and discard it, or have you got some
hints on where I can take this?

Jedd.





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