From abbcae8432ebcfd280927610a05ebe8ed8e9a693 Mon Sep 17 00:00:00 2001
From: AJ Ashton <aj.ashton@gmail.com>
Date: Thu, 25 May 2017 18:45:27 -0400
Subject: [PATCH] Sieve: avoid feeding non-polygons into ST_DumpRings

---
 postgis-vt-util.sql | 4 ++--
 src/Sieve.sql       | 4 ++--
 test/sql-test.sh    | 7 +++++++
 3 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/postgis-vt-util.sql b/postgis-vt-util.sql
index 32c37a5..d9291de 100644
--- a/postgis-vt-util.sql
+++ b/postgis-vt-util.sql
@@ -439,7 +439,7 @@ $func$
     with exploded as (
         -- First use ST_Dump to explode the input multipolygon
         -- to individual polygons.
-        select (ST_Dump(g)).geom
+        select (ST_Dump(ST_CollectionExtract(g, 3))).geom
     ), rings as (
         -- Next use ST_DumpRings to turn all of the inner and outer rings
         -- into their own separate polygons.
@@ -459,7 +459,7 @@ $func$
     with exploded as (
         -- First use ST_Dump to explode the input multipolygon
         -- to individual polygons.
-        select (ST_Dump(g)).geom
+        select (ST_Dump(ST_CollectionExtract(g, 3))).geom
     ), rings as (
         -- Next use ST_DumpRings to turn all of the inner and outer rings
         -- into their own separate polygons.
diff --git a/src/Sieve.sql b/src/Sieve.sql
index d32cc21..4379902 100644
--- a/src/Sieve.sql
+++ b/src/Sieve.sql
@@ -17,7 +17,7 @@ $func$
     with exploded as (
         -- First use ST_Dump to explode the input multipolygon
         -- to individual polygons.
-        select (ST_Dump(g)).geom
+        select (ST_Dump(ST_CollectionExtract(g, 3))).geom
     ), rings as (
         -- Next use ST_DumpRings to turn all of the inner and outer rings
         -- into their own separate polygons.
@@ -37,7 +37,7 @@ $func$
     with exploded as (
         -- First use ST_Dump to explode the input multipolygon
         -- to individual polygons.
-        select (ST_Dump(g)).geom
+        select (ST_Dump(ST_CollectionExtract(g, 3))).geom
     ), rings as (
         -- Next use ST_DumpRings to turn all of the inner and outer rings
         -- into their own separate polygons.
diff --git a/test/sql-test.sh b/test/sql-test.sh
index 1f885e5..b2c2acc 100755
--- a/test/sql-test.sh
+++ b/test/sql-test.sh
@@ -105,6 +105,13 @@ tf ST_AsText "Sieve(ST_GeomFromText('MULTIPOLYGON(\
     ((200 200,200 202,202 202,202 200,200 200)),\
     ((300 300,300 350,350 350,350 300,300 300)))'),10)" \
     "MULTIPOLYGON(((0 0,0 100,100 100,100 0,0 0),(50 50,60 50,60 60,50 60,50 50)),((300 300,300 350,350 350,350 300,300 300)))"
+tf ST_AsText "Sieve(ST_GeomFromText('GEOMETRYCOLLECTION(\
+    LINESTRING(-10 -10, -10 -100),\
+    MULTIPOLYGON(\
+    ((0 0,0 100,100 100,100 0,0 0),(10 10,12 10,12 12,10 12,10 10),(50 50,60 50,60 60,50 60,50 50)),\
+    ((200 200,200 202,202 202,202 200,200 200)),\
+    ((300 300,300 350,350 350,350 300,300 300))))'),10)" \
+    "MULTIPOLYGON(((0 0,0 100,100 100,100 0,0 0),(50 50,60 50,60 60,50 60,50 50)),((300 300,300 350,350 350,350 300,300 300)))"
 
 # SmartShrink
 tf floor "ST_Area(SmartShrink(ST_Buffer(ST_MakePoint(0,0),5000),0.5,true))" \