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Re: [Gnumed-devel] wells score - how to store it ?


From: Karsten Hilbert
Subject: Re: [Gnumed-devel] wells score - how to store it ?
Date: Tue, 5 Apr 2005 17:21:18 +0200
User-agent: Mutt/1.3.22.1i

>>>For storing small numbers of records, as in GNUmed,
>> Small numbers of records ? Where does large begin ?
> For population health work, I arbitrary regard small as up to 500,000
> records, medium as up to 5 million records, large as up to 25 million
> records, very large as up to several hundred million records and
> ginormous as more than that.
I see. What scope does "one record" have in this statement ?
Patients ? Rows in a table ? Entities (as in business
objects) ?

>>>the more flexible EAV (entity-attribute-value) model would be worth 
>>>considering.
> So all the data is stored in one table
IOW "form_data" with a structure ...

>, with one entity-attribute-value triplet per row?
... like this:

pk serial primary key,
fk_instance integer
    not null
    references form_instances(pk)
    on update cascade
    on delete restrict,
fk_form_field integer
    not null
    references form_fields(pk)
    on update cascade
    on delete restrict,
value text not null,
unique(fk_instance, fk_form_field)

which seems to suggest that, yes:

> That's the EAV model - although for storage efficinecy
> reasons, separate tables are often used for each data type.
... but which we don't do.

Karsten
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