[postgis-users] Intersection of 2 large maps overlap at a corner

[Bob and Deb]

Hello All,

I'm new to postgis and need help with (what seems to be a simple) query.

I have 2 geology maps that overlap at a corner:

----------------------------
|                          |
|                          |
|                 ---------|--------------
|                 |        |             |
----------------------------            |
                  |                     |
                  -----------------------

Below is the query that I used to do the job, but it takes a long time to
finish.  Any suggestions on improving it?

Thanks in advance!

Bob

SELECT
   ST_Intersection(GeoB.the_geom,GeoQ.the_geom) as intersect_geom,
   GeoB.*,
   GeoQ.*
FROM
   sj_100k_geopy as GeoB,
   sf_quat_geopy as GeoQ
WHERE
   ST_Intersects(GeoB.the_geom,GeoQ.the_geom)
AND
   GeoB.ptype not in ('Qls','Qls?')
AND
   GeoQ.ptype not in ('br','br?')
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