[postgis-users] looking for some perf data

[Martin Davis]

First of all, you need to be more specific.  The performance of an index 
is related to the kinds of queries you are making on it.   If you are 
making  a simple equality query, then a B-tree on the (x,y) pair is 
probably fine.  But if you're wanting to do range searches in two 
dimensions, a B-tree does not support this kind of query, and hence 
performance will be slow compared to an access method which does support 
this (e.g. R-tree, quad-tree, etc etc).

I don't know of any reference which has a "hard verifiable" comparison 
with a simple B-tree for range queries.  I suspect this is because the 
performance difference is so obviously bad for B-trees that researchers 
haven't bothered to document it. 

You might try looking at two of the books by Hanan Samet:

Foundations of Multidimensional and Metric Data Structures
The Design and Analysis of Spatial Data Structures

You could also try the original R-tree papers, or a survey entitled 
"R-Trees are everywhere".  Also a paper entitled "Multidimensional 
Access Methods" by Gaede et al.


raphael Jacquot wrote:
> hi there
> I'm looking for some hard verifiable proof that using r-tree based 
> geometry indexes is better than using 2 columns and a btree index on 
> it, performance wise.
>
> has there any study done on that ?
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-- 
Martin Davis
Senior Technical Architect
Refractions Research, Inc.
(250) 383-3022