From: Rob Sargent <robjsargent@gmail.com>
To: pgsql-sql@postgresql.org
Subject: Re: Type inheritance
Date: Sat, 6 Jun 2009 09:11:12 -0600
Message-ID: <5c4ddc540906060811i71e7892bqb208084512c92f90@mail.gmail.com> (raw)
In-Reply-To: <396486430906060730t1afd39a9p49b056158b1d2194@mail.gmail.com>
References: <5eca56860906050330w6171b327k95881b13c4dca466@mail.gmail.com>
<4A294A00.5020802@gmail.com>
<5eca56860906060010y4177b88apcf587d62f7286b5d@mail.gmail.com>
<396486430906060730t1afd39a9p49b056158b1d2194@mail.gmail.com>
On Sat, Jun 6, 2009 at 8:30 AM, Richard Broersma <richard.broersma@gmail.com
> wrote:
> On Sat, Jun 6, 2009 at 12:10 AM, Gianvito Pio<pio.gianvito@gmail.com>
> wrote:
>
> > That value doesn't have to be fixed, but I want to define it in a
> > way that it changes its structure when the sensor type changes. For
> > example, for Temperature sensor I would like to have just a float number,
> > but for the humidity I could need of absolute and relative humidity
> > (2 floats). I'd just like to know if I can say that the VALUE is a
> composite
> > type...that I have then to specialize in Temp Type and Humidity
> type...using
> > them in their particular case.
>
> I think that best solution for what you want to achieve is to design
> you own vertically partitioned table hierarchy. PostgreSQL's table
> inheritance isn't going to allow that relationships that you may want
> between the sub-types.
>
> Another PostgreSQL specific feature that allows for hierarchical data
> is the contrib module h-store. Its kind-of like EAV for a column
> instead of a table.
Are we storing sensor types (name, etc, sensor-report) where the report
column has to be polymorphic or are we storing instances of sensor results
(sensor-id, sensor-report). For the former a single table with an array of
number in the report column might work, for the latter it seems that
separate type specific tables extending/dependent to a table of sensors
could do the trick. What you're using to access the store might also affect
the design.
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To: pgsql-sql@postgresql.org
Cc: robjsargent@gmail.com
Subject: Re: Type inheritance
In-Reply-To: <5c4ddc540906060811i71e7892bqb208084512c92f90@mail.gmail.com>
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