The first step in this case may be to prepare the data. If we had a monolithic contour table called cuy_contours_2, we could choose to clip the data to a series of rectangles that will serve as our table partitions; in this case, chp02.contour_clip, using the following query:
CREATE TABLE chp02.contour_2_cm_only AS
SELECT contour.elevation, contour.gid, contour.div_10, contour.div_20, contour.div_50,
contour.div_100, cc.id, ST_Intersection(contour.the_geom, cc.the_geom) AS the_geom FROM
chp02.cuy_contours_2 AS contour, chp02.contour_clip as cc
WHERE ST_Within(contour.the_geom,cc.the_geom
OR
ST_Crosses(contour.the_geom,cc.the_geom);
We are performing two tests here in our query. We are using ST_Within, which tests whether ...
