I have a table of land parcels in my PostGIS database, and I'm doing a basic
spatial join against zoning polygons.
I'm having issues where a previously-correct query is now returning different
results.
Up until now, I've been using a Geoserver WFS, and making these queries using
CQL's INTERSECT operation. This operation generates a PostGIS query like so:
SELECT * FROM "public"."planning_zones" WHERE "geom" && ST_GeomFromWKB($1,
4326) AND ST_Intersects("geom", ST_GeomFromWKB($2, 4326)) LIMIT 1000000
As my land parcel dataset is snapped to my zoning polygons, this query causes
Geoserver to return a single record.
Now, I'm refactoring that query into a JSON API I'm building, and I'm
recreating that PostGIS query, and making the query directly to Postgres (not
Geoserver).
The problem is that the query is now returning multiple zoning polygons. The
difference is that I'm directly joining the zoning polys to the parcels:
SELECT * FROM zones AS z, parcels AS p ON ST_Intersects(z.geom, p.geom) WHERE
p.id = 99 AND z.geom && p.geom
This new query is returning multiple results, including polygons that share a
boundary. This didn't happen before.
Can anyone shed any light on why this might be happening? My suspicions are
that the tolerance of the Geoserver query differs to the raw PostGIS query, but
I'm uncertain how to best affect this.
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Timothy Asquith // Red Ronin
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