sql, geo: Fix upper case geohash parsing and allow NULL arguments

Release note (sql change): ST_Box2DFromGeoHash now accepts NULL arguments,
the precision being NULL is the same as no precision being passed in at all.

Upper case characters are now parsed as lower case characters for geohash,
this matches Postgis behaviour.

pkg/geo/parse.go

@@ -239,6 +239,9 @@ func parseGeoHash(g string, precision int) (geohash.Box, error) {
 		return geohash.Box{}, pgerror.Newf(pgcode.InvalidParameterValue, "length of GeoHash must be greater than 0")
 	}
 
+	// In PostGIS the parsing is case-insensitive.
+	g = strings.ToLower(g)
+
 	// If precision is more than the length of the geohash
 	// or if precision is less than 0 then set
 	// precision equal to length of geohash.

pkg/geo/parse_test.go

@@ -642,6 +642,17 @@ func TestParseHash(t *testing.T) {
 				Max: -120.9375,
 			},
 		}},
+		// In PostGIS the parsing is case-insensitive.
+		{"F", 1, geohash.Box{
+			Lat: geohash.Range{
+				Min: 45,
+				Max: 90,
+			},
+			Lon: geohash.Range{
+				Min: -90,
+				Max: -45,
+			},
+		}},
 	}
 	for _, tc := range testCases {
 		t.Run(fmt.Sprintf("%s[:%d]", tc.h, tc.p), func(t *testing.T) {

pkg/sql/logictest/testdata/logic_test/geospatial_bbox

@@ -243,3 +243,33 @@ BOX(0 0,0.00000000032741809263825417 0.00000000016370904631912708)
 BOX(20.012344998976914 -20.012345000286587,20.012345000286587 -20.012344998976914)
 BOX(90 0,90.00000000032742 0.00000000016370904631912708)
 BOX(90 0,90.0439453125 0.0439453125)
+
+query T
+SELECT ST_Box2DFromGeoHash('F'::TEXT::TEXT::TEXT, NULL::INT4::INT4)::BOX2D;
+----
+BOX(-90 45,-45 90)
+
+query T
+SELECT ST_Box2DFromGeoHash('kkqnpkue9ktbpe5', NULL)::BOX2D;
+----
+BOX(20.012344998976914 -20.012345000286587,20.012345000286587 -20.012344998976914)
+
+query T
+SELECT ST_Box2DFromGeoHash('KKQNPKUE9KTBPE5', NULL)::BOX2D;
+----
+BOX(20.012344998976914 -20.012345000286587,20.012345000286587 -20.012344998976914)
+
+query T
+SELECT ST_Box2DFromGeoHash('kKqNpKuE9KtBpE5', NULL)::BOX2D;
+----
+BOX(20.012344998976914 -20.012345000286587,20.012345000286587 -20.012344998976914)
+
+query T
+SELECT ST_Box2DFromGeoHash(NULL)::BOX2D;
+----
+NULL
+
+query T
+SELECT ST_Box2DFromGeoHash(NULL, NULL)::BOX2D;
+----
+NULL

pkg/sql/sem/builtins/geo_builtins.go

@@ -1185,17 +1185,28 @@ SELECT ST_S2Covering(geography, 's2_max_level=15,s2_level_mod=3').
 		},
 	),
 	"st_box2dfromgeohash": makeBuiltin(
-		defProps(),
+		tree.FunctionProperties{NullableArgs: true},
 		tree.Overload{
 			Types: tree.ArgTypes{
 				{"geohash", types.String},
 				{"precision", types.Int},
 			},
 			ReturnType: tree.FixedReturnType(types.Box2D),
 			Fn: func(ctx *tree.EvalContext, args tree.Datums) (tree.Datum, error) {
+				if args[0] == tree.DNull {
+					return tree.DNull, nil
+				}
+
 				g := tree.MustBeDString(args[0])
-				p := tree.MustBeDInt(args[1])
-				bbox, err := geo.ParseCartesianBoundingBoxFromGeoHash(string(g), int(p))
+
+				// Precision is allowed to be NULL, in that case treat it as if the
+				// argument had not been passed in at all
+				p := len(string(g))
+				if args[1] != tree.DNull {
+					p = int(tree.MustBeDInt(args[1]))
+				}
+
+				bbox, err := geo.ParseCartesianBoundingBoxFromGeoHash(string(g), p)
 				if err != nil {
 					return nil, err
 				}
@@ -1212,6 +1223,9 @@ SELECT ST_S2Covering(geography, 's2_max_level=15,s2_level_mod=3').
 			},
 			ReturnType: tree.FixedReturnType(types.Box2D),
 			Fn: func(ctx *tree.EvalContext, args tree.Datums) (tree.Datum, error) {
+				if args[0] == tree.DNull {
+					return tree.DNull, nil
+				}
 				g := tree.MustBeDString(args[0])
 				p := len(string(g))
 				bbox, err := geo.ParseCartesianBoundingBoxFromGeoHash(string(g), p)