[postgis-users] spatial indices on two geometry or rast columns

[Bryce L Nordgren]

postgis-users-bounces at postgis.refractions.net wrote on 08/11/2011 08:56:44 
PM:

> I am not planning to cearch using utm coordinates. The main reason I
> would create a utm geom, was so that I could calculate areas, 
> distances in sq km easily without having to include nested 
> ST_TRANSFORM statements. In this case would it be useful to have 
> another index on the utm?

I'd say that a good rule of thumb would be: 

If the WHERE clause of your SELECT statement names a geometry column, make 
an index on that column. If the column isn't in the WHERE clause, don't 
bother. :) 

Bryce
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/postgis-users/attachments/20110811/1e24c466/attachment.html>