Re: postgresql vs mysql - Mailing list pgsql-general

That's why you make a table for every device or every measurement, and
then use a view to consolidate it.  With updatable views, there's no
excuse not to.

--
Brandon Aiken
CS/IT Systems Engineer

-----Original Message-----
From: pgsql-general-owner@postgresql.org
[mailto:pgsql-general-owner@postgresql.org] On Behalf Of Steve Crawford
Sent: Friday, February 23, 2007 1:04 PM
To: Mark Walker
Cc: pgsql-general@postgresql.org
Subject: Re: [GENERAL] postgresql vs mysql

Mark Walker wrote:
> I'm not sure what you're trying to do but, it appears that you
database
> design is incorrect.  What you need is something like
>
> CREATE TABLE temp_readings
> (
>  _date Date,
>  temperature double,
>  source varchar(20),
> )
>
> No reading, no record.  Are you suggesting that you would have a
weekly
> set of records for each row?
>
> CREATE TABLE temp_readings
> (
>  weekstart date,
>  sun double,
>    mon double,
> tues, double
> etc
> )
>
> Not such a great way to do it.

Ummm, I'm not trying to make a temperature database. I was responding to
the previous poster with an extremely simple example of usefulness of
the _concept_ of "null".  I'm afraid I hadn't considered the possibility
that it would be mistaken as an example of an actual table.

But since you bring it up, simply omitting rows isn't necessarily an
option. A common scenario for weather observation is to take regular
snapshots or a bunch of measurements (air-temperature, humidity,
wind-speed, soil-temperature, leaf-wetness, UV radiation, etc.) which
can easily be represented in a table with a timestamp and a column for
each of the measurements. In a modular weather station where a specific
instrument can be out of service, one or more of those measurements
could be missing (null) for a period of time while the remaining
measurements are still being inserted.

Cheers,
Steve


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