Re: cube operations

Hi,
But now having 12 columns and multicolumn index, wont this slow down 
the search process. I mean in general retrieving 12 columns using a 
multicolumn index is slower or faster compared to an index on a 12 size 
array?

Thanks
Abhang
Quoting "John D. Burger" :

> ABHANG RANE wrote:
>
>> I have a array column which has 12 real values in it. Basically
>> these values represent co-ordinates in 12 dimensions for a
>> substance. My main need is to find substances similar to a
>> particular compound. Now I can do by calculating differences with
>> each array in the whole table. But the table has millions of rows.
>> So I need some kinda higher dimensional index.
>
> Is there any particular reason you're using an array?  If every row
> has all twelve values, I'd just make them columns.  Then I could use
> a multi-column index.
>
>> I have read about the cube operation in postgre, can it be extended
>> to 12 dimensions or something like that.
>
> I have no experience with CUBE, but I think it's just a kind of
> summarization aggregate.
>
> It sounds like you want the Nearest Neighbor(s) of your "particular
> compound".  You might to read about that:
>
> http://en.wikipedia.org/wiki/Nearest_neighbor_search
>
> - John Burger
>   G63
>
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