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  • From: Sean Maley <semaley@yahoo.com>
  • To: pcdb <pcdb@lists.ibiblio.org>
  • Subject: Re: [pcdb] some ideas for data modeling
  • Date: Thu, 5 Apr 2007 07:29:32 -0700 (PDT)

----- Original Message ----
From: Paul Cereghino <paul.cereghino@comcast.net>
To: pcdb <pcdb@lists.ibiblio.org>
Sent: Wednesday, April 4, 2007 7:41:25 PM
Subject: Re: [pcdb] some ideas for data modelling

> Is there a specific table and relationship structure that
> you db-designers think of when I say hierarchy?

When I hear hierarchy, there are two possible translations when talking about
a schema configuration.

The first and most dangerous design involves a self-referential field
pointing to another record (a parent record).

SELECT child.name AS "child", parent.name AS "parent"
FROM table_foo parent, table_foo child
WHERE parent.foo_uid =* child.foo_parent_uid_fk -- no parent means root
record

The second involves normalization of information. Postgres has features that
best describe this. Say you start with a table for guild members. Next you
create tables for animal_member, mineral_member, and vegetable_member, which
all inherit attributes from the base guild_member table. This is great when
writing OOD code, but not as useful planning concurrency (Mu in RDB terms).

> Are there basic alternative models of adding attributes
> to objects that need to be selected among?!
> what are the different data structure choices... not for describing the
> relationship of the chicken to other objects... but of describing the
> characteristics of the chicken.... size, longevity, lifeform, breed, etc...
> What are the alternatives?bb

This can't be answered until data flow has been designed. What are the
inputs and outputs? Is there an example analysis that will be performed?
What would a data collection look like? Will they occur concurrently, or can
they be timed separately?

I'm imagining that guild design would collect information from various sites
with varying combinations of species and landscape features. I might sift
through harvest yields in relation to precipitation patterns and temperature
records. I might wish to compare my own design with that of others in
similar climates. Do they get a higher yield at the expense of biodiversity
or could they be doing something in their landscape or species arrangement
that makes a difference? Are they doing more work to get their results?

On the other hand, the more information you attempt to collect, the less
likely there will be cooperation to collect it. In this case, what would it
take to get this information? An automated weather station would deal with
climatic data collection. CSA farmer planning tools and corresponding CSA
subscriber menu planning/nutritional calculator would help indirectly collect
harvest data. A farmer blog would help indirectly detail site information,
which the analysis would directly use to cue into why a given Permaculture
design was getting more of something than another was getting.

These are just examples. What kinds of things do we want the data to be able
to tell us? What kinds of information do we think we could reliably collect?
I have a background in electronics, so I see the internet aware weather
station as very doable, if only there were the time to invent it. Similar
things could be achieved in compost piles, but don't forget that cell phones
could potentially collect data, as well. How many other inventions and data
collection innovations could we create? All of this opportunity and nobody
is even thinking about this stuff yet. Anyone else feel like a kid in a
candy store?


-Sean.






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  • Re: [pcdb] some ideas for data modeling, Sean Maley, 04/05/2007

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