Archetype relational mapping - a practical openEHR persistence solution

Thomas Beale thomas.beale at openehr.org
Tue Feb 16 05:47:16 EST 2016



On 14/02/2016 23:25, Bert Verhees wrote:
>
> One doesn't know what software really does. One must distinguish what 
> software seems to do and what it really does.
>
> Storing XML really as XML means, storing a lot of redundant 
> information. I don't know, but I cannot believe postgress really 
> stores the full tag names,  even when they occur thousand times. I 
> would be really disappointed if they do.
>
> Bert
>

storing a text serialisation of an object structure in a database never 
makes sense when you think about it. Storing a /binary/ serialisation is 
a normal 'blob' approach, and if you are not doing blobs or partial 
blobs, then you are doing transparent representation, in which case 
things like XML or JSON don't come into it - they only make sense as one 
kind of generated view on data.

You might implement blobs using a zipped text format, but in a serious 
scalable implementation that would surely have to be the least efficient 
of viable approaches.

I can't think of any circumstance where a DB would actually store its 
information as XML instance text (other than where some column value 
happened to be an XMLstring, i.e. the XML is just data).

- thomas
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