[postgis-users] Problem with &&-operator and transform()

[Christian Schwartze]

Hi to all PostGIS-users....

I have a table "earthquakes" with a GiSt-index on column "geo". I search for all earthquakes along a street using a buffer distance.
Does somebody know, why the GiST-index is not in use (as per explain), when combining the &&-operator with the transform()-function like in:

select quake_id, location, x(geo), y(geo) 
from earthquakes 
where geo && envelope(buffer(transform((select geo from roads where name = 'U.S. Hwy 85'),102009),5)) and within(geo,(select buffer(transform((select geo from roads where name = 'U.S. Hwy 85'),102009),5)));

Without the transform-function the query is very quick because of the GiST-index, but i need the transform-function to calculate in unit "meter".

Can somebody help me, thanks a lot!

Christian.
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