[postgis-users] Topology Issue Reported by Query but Not Identified with ST_IsValid

[Michael Treglia]

Hi All,

I was running a query involving ST_Difference between two multipolygon
layers, and a while in, it threw this message:
ERROR: GEOSDifference: TopologyException: side location conflict at
919670.1768945494 140665.82566365649

However, I previously ran ST_MakeValid, and ST_IsValid doesn't report any
objects with problems. Is there something I'm missing, or something else I
need to check? (Apologies is this is just a naive question - still learning
my way around PostGIS).

And in case it helps, here's my SQL:

CREATE TABLE SI_Unclaimed AS
SELECT gid, COALESCE(ST_Difference(geom_2263, (SELECT
ST_Collect(b.geom_2263)
                                         FROM citywide_basedata.parcels15 b
                                         WHERE ST_Intersects(a.geom_2263,
b.geom_2263)
                                         )), a.geom_2263)
FROM citywide_basedata.boroughs_nowater a where boroname like 'Staten
Island';

Thanks!
Mike
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