Re: Dynamic data model, locks and performance

On 07/29/2010 05:15 AM, Pierre Thibault wrote:
> 2010/7/28 Craig Ringer <craig@postnewspapers.com.au 
> <mailto:craig@postnewspapers.com.au>>
>
>     On 29/07/10 07:06, Pierre Thibault wrote:
>     I doubt anyone can make any useful recommendations without a more
>     complete explanation of what you're trying to achieve and why you want
>     to do what you have described.
>
>
> Thank you Craig,
>
> Yes, I was not very specific. I have an idea in mind. Everyone knows 
> about Craig's List and the hype about NoSql databases. This seems to 
> be cool to do full text searches in a lot of data. But what about 
> doing more formal searches based specific criteria like dates, numbers 
> or other kind values on specific fields? This where an SQL database 
> shines.
>
> What I would like to do is enable users to create their own data 
> model. Enable them to create a model and make it evolve. For example, 
> it would be cool to create a model to represent car adds. Then, the 
> buyers can search adds using the previous model with specific criteria 
> like the color of the car they want.
>
> I thought about using a table where each row would represents a field 
> in the dynamic model. The row would contain a fields for each possible 
> data type supported but only one of them would be used. This would 
> waste a lot space and it would also be hard to query efficiently but I 
> will not have to change the schema as users create new models. 
> Otherwise, I would create a standard data model and apply the changes 
> as users update their models.
>
> I also like to support inheritance so we can have a simple model for 
> regular adds and more specfic models with more fields for car adds for 
> example.
>
> I have a really hard finding how to implement my idea efficiently. So 
> the advice of experienced database developers is what I am looking for.
>
>
>     Re Pg-specific stuff, you should look into hstore. It might offer
>     a way
>     to avoid the need for dynamic table re-structuring.
>
>
> I thought about using maps for the entities of my domain model. hstore 
> seems to be an interesting avenue.
>

You might want to take a look at TopicMaps, http://www.topicmaps.org/
One of the greatest topicmap-engines is opensource: http://www.ontopia.net/
It uses, if you want, an RDBMS (PostgreSQL is fully supported) underneath.

-- 
Andreas Joseph Krogh<andreak@officenet.no>
Senior Software Developer / CTO
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