Avoid creating GridCluster overviews for non-point datasets

scripts-available/CDB_Overviews.sql

@@ -513,6 +513,28 @@ BEGIN
 END
 $$ LANGUAGE PLPGSQL STABLE;
 
+-- Array of geometry types detected in a cartodbfied table
+-- For effciency only look at a limited number of rwos.
+-- Parameters
+--   reloid: oid of the input table. It must be a cartodbfy'ed table.
+-- Return value: array of geometry type names
+CREATE OR REPLACE FUNCTION _CDB_GeometryTypes(reloid REGCLASS)
+RETURNS TEXT[]
+AS $$
+DECLARE
+  gtypes TEXT[];
+BEGIN
+  EXECUTE Format('
+    SELECT array_agg(DISTINCT ST_GeometryType(the_geom)) FROM (
+      SELECT the_geom FROM %s
+        WHERE (the_geom is not null) LIMIT 10
+    ) as geom_types
+  ', reloid)
+  INTO gtypes;
+  RETURN gtypes;
+END
+$$ LANGUAGE PLPGSQL STABLE;
+
 -- Experimental Overview reduction method for point datasets.
 -- It clusters the points using a grid, then aggregates the point in each
 -- cluster into a point at the centroid of the clustered records.
@@ -535,7 +557,17 @@ AS $$
     aggr_attributes TEXT;
     attributes TEXT;
     columns TEXT;
+    gtypes TEXT[];
   BEGIN
+    SELECT _CDB_GeometryTypes(reloid) INTO gtypes;
+    IF array_upper(gtypes, 1) <> 1 OR gtypes[1] <> 'ST_Point' THEN
+      -- This strategy only supports datasets with point geomety
+      RETURN NULL;
+      RETURN 'x';
+    END IF;
+
+    --TODO: check applicability: geometry type, minimum number of points...
+
     overview_rel := _CDB_Overview_Name(reloid, ref_z, overview_z);
 
     -- compute grid cell size using the overview_z dimension...
@@ -630,7 +662,7 @@ BEGIN
   EXECUTE 'SELECT ' || quote_ident(refscale_strategy::text) || Format('(''%s'');', reloid) INTO ref_z;
 
   -- Determine overlay zoom levels
-  -- TODO: should be handled by the refscale_stragegy?
+  -- TODO: should be handled by the refscale_strategy?
   overview_z := ref_z - 1;
   WHILE overview_z >= 0 LOOP
     SELECT array_append(overviews_z, overview_z) INTO overviews_z;
@@ -642,6 +674,9 @@ BEGIN
   base_rel := reloid;
   FOREACH overview_z IN ARRAY overviews_z LOOP
     EXECUTE 'SELECT ' || quote_ident(reduce_strategy::text) || Format('(''%s'', %s, %s);', base_rel, base_z, overview_z) INTO base_rel;
+    IF base_rel IS NULL THEN
+      EXIT;
+    END IF;
     base_z := overview_z;
     PERFORM _CDB_Register_Overview(reloid, base_rel, base_z);
     SELECT array_append(overview_tables, base_rel) INTO overview_tables;

test/CDB_OverviewsTest.sql

@@ -18,8 +18,11 @@ SELECT _CDB_Aggregated_Attributes_Expression('base_t'::regclass, 'tab');
 SELECT CDB_CreateOverviews('base_t'::regclass);
 SELECT count(*) FROM _vovw_5_base_t;
 
+SELECT CDB_CreateOverviews('polyg_t'::regclass);
+
 SELECT CDB_Overviews('base_t'::regclass);
 SELECT CDB_Overviews(ARRAY['base_t'::regclass, 'base_bare_t'::regclass]);
+SELECT CDB_Overviews('polyg_t'::regclass);
 
 SELECT CDB_DropOverviews('base_bare_t'::regclass);
 SELECT CDB_DropOverviews('base_t'::regclass);
@@ -27,3 +30,4 @@ SELECT count(*) FROM _vovw_5_base_t;
 
 DROP TABLE base_bare_t;
 DROP TABLE base_t;
+DROP TABLE polyg_t;

test/CDB_OverviewsTest_expect

@@ -3,6 +3,8 @@ CREATE TABLE
 INSERT 0 1114
 CREATE TABLE
 INSERT 0 1114
+CREATE TABLE
+INSERT 0 5
 
 
 
@@ -13,6 +15,7 @@ AVG(number)::double precision AS number,AVG(int_number)::integer AS int_number,C
 AVG(tab.number)::double precision AS number,AVG(tab.int_number)::integer AS int_number,CASE count(*) WHEN 1 THEN MIN(tab.name) ELSE NULL END::text AS name,CASE count(*) WHEN 1 THEN MIN(tab.start) ELSE NULL END::date AS start
 {_vovw_5_base_t,_vovw_4_base_t,_vovw_3_base_t,_vovw_2_base_t,_vovw_1_base_t,_vovw_0_base_t}
 125
+
 (base_t,0,_vovw_0_base_t)
 (base_t,1,_vovw_1_base_t)
 (base_t,2,_vovw_2_base_t)
@@ -38,3 +41,4 @@ LINE 1: SELECT count(*) FROM _vovw_5_base_t;
                              ^
 DROP TABLE
 DROP TABLE
+DROP TABLE

test/overviews/fixtures.sql

@@ -2232,3 +2232,11 @@ INSERT INTO base_t VALUES
 (1112, 'SRID=4326;POINT(-1.544993 33.333714)'::geometry, ST_Transform('SRID=4326;POINT(-1.544993 33.333714)'::geometry, 3857)),
 (1113, 'SRID=4326;POINT(-1.544859 33.333711)'::geometry, ST_Transform('SRID=4326;POINT(-1.544859 33.333711)'::geometry, 3857)),
 (1114, 'SRID=4326;POINT(-1.544863 33.334479)'::geometry, ST_Transform('SRID=4326;POINT(-1.544863 33.334479)'::geometry, 3857));
+-- polygons table
+CREATE TABLE polyg_t (cartodb_id integer, name text, the_geom geometry, the_geom_webmercator geometry);
+INSERT INTO polyg_t VALUES
+(1, 'A', 'SRID=4326;POLYGON((9 40,8 39,8.5 40,9 41,9 40))'::geometry, ST_Transform('SRID=4326;POLYGON((9 40,8 39,8.5 40,9 41,9 40))'::geometry, 3857)),
+(2, 'B', 'SRID=4326;POLYGON((9 40,8 39,8.5 40,9 41,9 40))'::geometry, ST_Transform('SRID=4326;POLYGON((9 40,8 39,8.5 40,9 41,9 40))'::geometry, 3857)),
+(3, 'C', 'SRID=4326;POLYGON((9 40,8 39,8.5 40,9 41,9 40))'::geometry, ST_Transform('SRID=4326;POLYGON((9 40,8 39,8.5 40,9 41,9 40))'::geometry, 3857)),
+(4, 'D', 'SRID=4326;POLYGON((9 40,8 39,8.5 40,9 41,9 40))'::geometry, ST_Transform('SRID=4326;POLYGON((9 40,8 39,8.5 40,9 41,9 40))'::geometry, 3857)),
+(5, 'E', 'SRID=4326;POLYGON((9 40,8 39,8.5 40,9 41,9 40))'::geometry, ST_Transform('SRID=4326;POLYGON((9 40,8 39,8.5 40,9 41,9 40))'::geometry, 3857));