Fix core dump in jsonb #> operator, and add regression test cases.

jsonb's #> operator segfaulted (dereferencing a null pointer) if the RHS
was a zero-length array, as reported in bug #11207 from Justin Van Winkle.
json's #> operator returns NULL in such cases, so for the moment let's
make jsonb act likewise.

Also add a bunch of regression test queries memorializing the -> and #>
operators' behavior for this and other corner cases.

There is a good argument for changing some of these behaviors, as they
are not very consistent with each other, and throwing an error isn't
necessarily a desirable behavior for operators that are likely to be
used in indexes.  However, everybody can agree that a core dump is the
Wrong Thing, and we need test cases even if we decide to change their
expected output later.

src/backend/utils/adt/jsonfuncs.c

@@ -726,6 +726,13 @@ get_path_all(FunctionCallInfo fcinfo, const char *funcname, bool as_text)
 	deconstruct_array(path, TEXTOID, -1, false, 'i',
 					  &pathtext, &pathnulls, &npath);
 
+	/*
+	 * If the array is empty, return NULL; this is dubious but it's what 9.3
+	 * did.
+	 */
+	if (npath <= 0)
+		PG_RETURN_NULL();
+
 	tpath = palloc(npath * sizeof(char *));
 	ipath = palloc(npath * sizeof(int));
 
@@ -1100,11 +1107,11 @@ get_jsonb_path_all(FunctionCallInfo fcinfo, const char *funcname, bool as_text)
 {
 	Jsonb	   *jb = PG_GETARG_JSONB(0);
 	ArrayType  *path = PG_GETARG_ARRAYTYPE_P(1);
+	Jsonb	   *res;
 	Datum	   *pathtext;
 	bool	   *pathnulls;
 	int			npath;
 	int			i;
-	Jsonb	   *res;
 	bool		have_object = false,
 				have_array = false;
 	JsonbValue *jbvp = NULL;
@@ -1120,6 +1127,13 @@ get_jsonb_path_all(FunctionCallInfo fcinfo, const char *funcname, bool as_text)
 	deconstruct_array(path, TEXTOID, -1, false, 'i',
 					  &pathtext, &pathnulls, &npath);
 
+	/*
+	 * If the array is empty, return NULL; this is dubious but it's what 9.3
+	 * did.
+	 */
+	if (npath <= 0)
+		PG_RETURN_NULL();
+
 	if (JB_ROOT_IS_OBJECT(jb))
 		have_object = true;
 	else if (JB_ROOT_IS_ARRAY(jb) && !JB_ROOT_IS_SCALAR(jb))

src/test/regress/expected/json.out

@@ -653,6 +653,45 @@ where json_type = 'array';
  t
 (1 row)
 
+-- corner cases
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> null::text;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> null::int;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> 1;
+ERROR:  cannot extract array element from a non-array
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> 'z';
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json -> 1;
+  ?column?   
+-------------
+ {"b": "cc"}
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json -> 3;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json -> 'z';
+ERROR:  cannot extract field from a non-object
+select '"foo"'::json -> 1;
+ERROR:  cannot extract element from a scalar
+select '"foo"'::json -> 'z';
+ERROR:  cannot extract element from a scalar
 -- array length
 SELECT json_array_length('[1,2,3,{"f1":1,"f2":[5,6]},4]');
  json_array_length 
@@ -831,53 +870,161 @@ select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>array['f2','1'];
  1
 (1 row)
 
--- same using array literals
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f4,f6}';
- ?column?  
------------
- "stringy"
-(1 row)
-
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f2}';
+-- corner cases for same
+select '{"a": {"b":{"c": "foo"}}}'::json #> array[]::text[];
  ?column? 
 ----------
- {"f3":1}
+ 
 (1 row)
 
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f2,0}';
- ?column? 
-----------
- "f3"
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a'];
+      ?column?      
+--------------------
+ {"b":{"c": "foo"}}
 (1 row)
 
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f2,1}';
- ?column? 
-----------
- 1
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b'];
+   ?column?   
+--------------
+ {"c": "foo"}
 (1 row)
 
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f4,f6}';
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b','c'];
  ?column? 
 ----------
- stringy
+ "foo"
 (1 row)
 
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f2}';
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b','c','d'];
  ?column? 
 ----------
- {"f3":1}
+ 
 (1 row)
 
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f2,0}';
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','z','c'];
  ?column? 
 ----------
- f3
+ 
 (1 row)
 
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f2,1}';
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #> array['a','1','b'];
  ?column? 
 ----------
- 1
+ "cc"
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #> array['a','z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json #> array['1','b'];
+ ?column? 
+----------
+ "cc"
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json #> array['z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '"foo"'::json #> array['z'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '42'::json #> array['f2'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '42'::json #> array['0'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array[]::text[];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a'];
+      ?column?      
+--------------------
+ {"b":{"c": "foo"}}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b'];
+   ?column?   
+--------------
+ {"c": "foo"}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b','c'];
+ ?column? 
+----------
+ foo
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b','c','d'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','z','c'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #>> array['a','1','b'];
+ ?column? 
+----------
+ cc
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #>> array['a','z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json #>> array['1','b'];
+ ?column? 
+----------
+ cc
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json #>> array['z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '"foo"'::json #>> array['z'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '42'::json #>> array['f2'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '42'::json #>> array['0'];
+ ?column? 
+----------
+ 
 (1 row)
 
 -- array_elements

src/test/regress/expected/json_1.out

@@ -653,6 +653,45 @@ where json_type = 'array';
  t
 (1 row)
 
+-- corner cases
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> null::text;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> null::int;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> 1;
+ERROR:  cannot extract array element from a non-array
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> 'z';
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json -> 1;
+  ?column?   
+-------------
+ {"b": "cc"}
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json -> 3;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json -> 'z';
+ERROR:  cannot extract field from a non-object
+select '"foo"'::json -> 1;
+ERROR:  cannot extract element from a scalar
+select '"foo"'::json -> 'z';
+ERROR:  cannot extract element from a scalar
 -- array length
 SELECT json_array_length('[1,2,3,{"f1":1,"f2":[5,6]},4]');
  json_array_length 
@@ -831,53 +870,161 @@ select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>array['f2','1'];
  1
 (1 row)
 
--- same using array literals
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f4,f6}';
- ?column?  
------------
- "stringy"
-(1 row)
-
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f2}';
+-- corner cases for same
+select '{"a": {"b":{"c": "foo"}}}'::json #> array[]::text[];
  ?column? 
 ----------
- {"f3":1}
+ 
 (1 row)
 
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f2,0}';
- ?column? 
-----------
- "f3"
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a'];
+      ?column?      
+--------------------
+ {"b":{"c": "foo"}}
 (1 row)
 
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f2,1}';
- ?column? 
-----------
- 1
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b'];
+   ?column?   
+--------------
+ {"c": "foo"}
 (1 row)
 
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f4,f6}';
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b','c'];
  ?column? 
 ----------
- stringy
+ "foo"
 (1 row)
 
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f2}';
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b','c','d'];
  ?column? 
 ----------
- {"f3":1}
+ 
 (1 row)
 
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f2,0}';
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','z','c'];
  ?column? 
 ----------
- f3
+ 
 (1 row)
 
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f2,1}';
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #> array['a','1','b'];
  ?column? 
 ----------
- 1
+ "cc"
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #> array['a','z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json #> array['1','b'];
+ ?column? 
+----------
+ "cc"
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json #> array['z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '"foo"'::json #> array['z'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '42'::json #> array['f2'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '42'::json #> array['0'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array[]::text[];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a'];
+      ?column?      
+--------------------
+ {"b":{"c": "foo"}}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b'];
+   ?column?   
+--------------
+ {"c": "foo"}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b','c'];
+ ?column? 
+----------
+ foo
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b','c','d'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','z','c'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #>> array['a','1','b'];
+ ?column? 
+----------
+ cc
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #>> array['a','z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json #>> array['1','b'];
+ ?column? 
+----------
+ cc
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::json #>> array['z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '"foo"'::json #>> array['z'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '42'::json #>> array['f2'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '42'::json #>> array['0'];
+ ?column? 
+----------
+ 
 (1 row)
 
 -- array_elements

src/test/regress/expected/jsonb.out

@@ -432,6 +432,45 @@ SELECT (test_json->>3) IS NULL AS expect_true FROM test_jsonb WHERE json_type =
  t
 (1 row)
 
+-- corner cases
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> null::text;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> null::int;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> 1;
+ERROR:  cannot call jsonb_array_element (jsonb -> int) on an object
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> 'z';
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 1;
+  ?column?   
+-------------
+ {"b": "cc"}
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 3;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 'z';
+ERROR:  cannot call jsonb_object_field (jsonb -> text) on an array
+select '"foo"'::jsonb -> 1;
+ERROR:  cannot call jsonb_array_element (jsonb -> int) on a scalar
+select '"foo"'::jsonb -> 'z';
+ERROR:  cannot call jsonb_object_field (jsonb -> text) on a scalar
 -- equality and inequality
 SELECT '{"x":"y"}'::jsonb = '{"x":"y"}'::jsonb;
  ?column? 
@@ -1178,63 +1217,138 @@ SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>array['f2','1'];
  1
 (1 row)
 
--- same using array literals
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f4,f6}';
- ?column?  
------------
- "stringy"
-(1 row)
-
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f2}';
- ?column?  
------------
- {"f3": 1}
-(1 row)
-
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f2,0}';
+-- corner cases for same
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array[]::text[];
  ?column? 
 ----------
- "f3"
+ 
 (1 row)
 
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f2,1}';
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a'];
+      ?column?       
+---------------------
+ {"b": {"c": "foo"}}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','b'];
+   ?column?   
+--------------
+ {"c": "foo"}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','b','c'];
  ?column? 
 ----------
- 1
+ "foo"
 (1 row)
 
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f4,f6}';
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','b','c','d'];
  ?column? 
 ----------
- stringy
+ 
 (1 row)
 
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f2}';
- ?column?  
------------
- {"f3": 1}
-(1 row)
-
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f2,0}';
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','z','c'];
  ?column? 
 ----------
- f3
+ 
 (1 row)
 
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f2,1}';
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #> array['a','1','b'];
  ?column? 
 ----------
- 1
+ "cc"
 (1 row)
 
--- same on jsonb scalars (expecting errors)
-SELECT '42'::jsonb#>array['f2'];
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #> array['a','z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #> array['1','b'];
+ ?column? 
+----------
+ "cc"
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #> array['z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '"foo"'::jsonb #> array['z'];
 ERROR:  cannot extract path from a scalar
-SELECT '42'::jsonb#>array['0'];
+select '42'::jsonb #> array['f2'];
 ERROR:  cannot extract path from a scalar
-SELECT '42'::jsonb#>>array['f2'];
+select '42'::jsonb #> array['0'];
 ERROR:  cannot extract path from a scalar
-SELECT '42'::jsonb#>>array['0'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array[]::text[];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a'];
+      ?column?       
+---------------------
+ {"b": {"c": "foo"}}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','b'];
+   ?column?   
+--------------
+ {"c": "foo"}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','b','c'];
+ ?column? 
+----------
+ foo
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','b','c','d'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','z','c'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #>> array['a','1','b'];
+ ?column? 
+----------
+ cc
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #>> array['a','z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #>> array['1','b'];
+ ?column? 
+----------
+ cc
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #>> array['z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '"foo"'::jsonb #>> array['z'];
+ERROR:  cannot extract path from a scalar
+select '42'::jsonb #>> array['f2'];
+ERROR:  cannot extract path from a scalar
+select '42'::jsonb #>> array['0'];
 ERROR:  cannot extract path from a scalar
 -- array_elements
 SELECT jsonb_array_elements('[1,true,[1,[2,3]],null,{"f1":1,"f2":[7,8,9]},false]');

src/test/regress/expected/jsonb_1.out

@@ -432,6 +432,45 @@ SELECT (test_json->>3) IS NULL AS expect_true FROM test_jsonb WHERE json_type =
  t
 (1 row)
 
+-- corner cases
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> null::text;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> null::int;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> 1;
+ERROR:  cannot call jsonb_array_element (jsonb -> int) on an object
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> 'z';
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 1;
+  ?column?   
+-------------
+ {"b": "cc"}
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 3;
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 'z';
+ERROR:  cannot call jsonb_object_field (jsonb -> text) on an array
+select '"foo"'::jsonb -> 1;
+ERROR:  cannot call jsonb_array_element (jsonb -> int) on a scalar
+select '"foo"'::jsonb -> 'z';
+ERROR:  cannot call jsonb_object_field (jsonb -> text) on a scalar
 -- equality and inequality
 SELECT '{"x":"y"}'::jsonb = '{"x":"y"}'::jsonb;
  ?column? 
@@ -1178,63 +1217,138 @@ SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>array['f2','1'];
  1
 (1 row)
 
--- same using array literals
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f4,f6}';
- ?column?  
------------
- "stringy"
-(1 row)
-
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f2}';
- ?column?  
------------
- {"f3": 1}
-(1 row)
-
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f2,0}';
+-- corner cases for same
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array[]::text[];
  ?column? 
 ----------
- "f3"
+ 
 (1 row)
 
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f2,1}';
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a'];
+      ?column?       
+---------------------
+ {"b": {"c": "foo"}}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','b'];
+   ?column?   
+--------------
+ {"c": "foo"}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','b','c'];
  ?column? 
 ----------
- 1
+ "foo"
 (1 row)
 
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f4,f6}';
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','b','c','d'];
  ?column? 
 ----------
- stringy
+ 
 (1 row)
 
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f2}';
- ?column?  
------------
- {"f3": 1}
-(1 row)
-
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f2,0}';
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','z','c'];
  ?column? 
 ----------
- f3
+ 
 (1 row)
 
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f2,1}';
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #> array['a','1','b'];
  ?column? 
 ----------
- 1
+ "cc"
 (1 row)
 
--- same on jsonb scalars (expecting errors)
-SELECT '42'::jsonb#>array['f2'];
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #> array['a','z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #> array['1','b'];
+ ?column? 
+----------
+ "cc"
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #> array['z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '"foo"'::jsonb #> array['z'];
 ERROR:  cannot extract path from a scalar
-SELECT '42'::jsonb#>array['0'];
+select '42'::jsonb #> array['f2'];
 ERROR:  cannot extract path from a scalar
-SELECT '42'::jsonb#>>array['f2'];
+select '42'::jsonb #> array['0'];
 ERROR:  cannot extract path from a scalar
-SELECT '42'::jsonb#>>array['0'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array[]::text[];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a'];
+      ?column?       
+---------------------
+ {"b": {"c": "foo"}}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','b'];
+   ?column?   
+--------------
+ {"c": "foo"}
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','b','c'];
+ ?column? 
+----------
+ foo
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','b','c','d'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','z','c'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #>> array['a','1','b'];
+ ?column? 
+----------
+ cc
+(1 row)
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #>> array['a','z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #>> array['1','b'];
+ ?column? 
+----------
+ cc
+(1 row)
+
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #>> array['z','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
+select '"foo"'::jsonb #>> array['z'];
+ERROR:  cannot extract path from a scalar
+select '42'::jsonb #>> array['f2'];
+ERROR:  cannot extract path from a scalar
+select '42'::jsonb #>> array['0'];
 ERROR:  cannot extract path from a scalar
 -- array_elements
 SELECT jsonb_array_elements('[1,true,[1,[2,3]],null,{"f1":1,"f2":[7,8,9]},false]');

src/test/regress/sql/json.sql

@@ -238,6 +238,17 @@ select (test_json->>3) is null as expect_true
 from test_json
 where json_type = 'array';
 
+-- corner cases
+
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> null::text;
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> null::int;
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> 1;
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> 'z';
+select '[{"b": "c"}, {"b": "cc"}]'::json -> 1;
+select '[{"b": "c"}, {"b": "cc"}]'::json -> 3;
+select '[{"b": "c"}, {"b": "cc"}]'::json -> 'z';
+select '"foo"'::json -> 1;
+select '"foo"'::json -> 'z';
 
 -- array length
 
@@ -281,20 +292,40 @@ select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>array['f4','f6'];
 select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>array['f2'];
 select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>array['f2','0'];
 select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>array['f2','1'];
+
 select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>>array['f4','f6'];
 select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>>array['f2'];
 select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>array['f2','0'];
 select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>array['f2','1'];
 
--- same using array literals
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f4,f6}';
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f2}';
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f2,0}';
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>'{f2,1}';
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f4,f6}';
-select '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f2}';
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f2,0}';
-select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>'{f2,1}';
+-- corner cases for same
+select '{"a": {"b":{"c": "foo"}}}'::json #> array[]::text[];
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a'];
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b'];
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b','c'];
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b','c','d'];
+select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','z','c'];
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #> array['a','1','b'];
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #> array['a','z','b'];
+select '[{"b": "c"}, {"b": "cc"}]'::json #> array['1','b'];
+select '[{"b": "c"}, {"b": "cc"}]'::json #> array['z','b'];
+select '"foo"'::json #> array['z'];
+select '42'::json #> array['f2'];
+select '42'::json #> array['0'];
+
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array[]::text[];
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a'];
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b'];
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b','c'];
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b','c','d'];
+select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','z','c'];
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #>> array['a','1','b'];
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json #>> array['a','z','b'];
+select '[{"b": "c"}, {"b": "cc"}]'::json #>> array['1','b'];
+select '[{"b": "c"}, {"b": "cc"}]'::json #>> array['z','b'];
+select '"foo"'::json #>> array['z'];
+select '42'::json #>> array['f2'];
+select '42'::json #>> array['0'];
 
 -- array_elements
 

src/test/regress/sql/jsonb.sql

@@ -108,6 +108,17 @@ SELECT (test_json->>'field3') IS NULL AS expect_true FROM test_jsonb WHERE json_
 SELECT (test_json->3) IS NULL AS expect_false FROM test_jsonb WHERE json_type = 'array';
 SELECT (test_json->>3) IS NULL AS expect_true FROM test_jsonb WHERE json_type = 'array';
 
+-- corner cases
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> null::text;
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> null::int;
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> 1;
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> 'z';
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 1;
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 3;
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 'z';
+select '"foo"'::jsonb -> 1;
+select '"foo"'::jsonb -> 'z';
+
 -- equality and inequality
 SELECT '{"x":"y"}'::jsonb = '{"x":"y"}'::jsonb;
 SELECT '{"x":"y"}'::jsonb = '{"x":"z"}'::jsonb;
@@ -252,26 +263,40 @@ SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>array['f4','f6'];
 SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>array['f2'];
 SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>array['f2','0'];
 SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>array['f2','1'];
+
 SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>array['f4','f6'];
 SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>array['f2'];
 SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>array['f2','0'];
 SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>array['f2','1'];
 
--- same using array literals
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f4,f6}';
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f2}';
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f2,0}';
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>'{f2,1}';
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f4,f6}';
-SELECT '{"f2":{"f3":1},"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f2}';
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f2,0}';
-SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>'{f2,1}';
+-- corner cases for same
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array[]::text[];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','b'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','b','c'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','b','c','d'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a','z','c'];
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #> array['a','1','b'];
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #> array['a','z','b'];
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #> array['1','b'];
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #> array['z','b'];
+select '"foo"'::jsonb #> array['z'];
+select '42'::jsonb #> array['f2'];
+select '42'::jsonb #> array['0'];
 
--- same on jsonb scalars (expecting errors)
-SELECT '42'::jsonb#>array['f2'];
-SELECT '42'::jsonb#>array['0'];
-SELECT '42'::jsonb#>>array['f2'];
-SELECT '42'::jsonb#>>array['0'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array[]::text[];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','b'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','b','c'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','b','c','d'];
+select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a','z','c'];
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #>> array['a','1','b'];
+select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb #>> array['a','z','b'];
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #>> array['1','b'];
+select '[{"b": "c"}, {"b": "cc"}]'::jsonb #>> array['z','b'];
+select '"foo"'::jsonb #>> array['z'];
+select '42'::jsonb #>> array['f2'];
+select '42'::jsonb #>> array['0'];
 
 -- array_elements
 SELECT jsonb_array_elements('[1,true,[1,[2,3]],null,{"f1":1,"f2":[7,8,9]},false]');