Fix corner-case behaviors in JSON/JSONB field extraction operators.

Cause the path extraction operators to return their lefthand input,
not NULL, if the path array has no elements.  This seems more consistent
since the case ought to correspond to applying the simple extraction
operator (->) zero times.

Cause other corner cases in field/element/path extraction to return NULL
rather than failing.  This behavior is arguably more useful than throwing
an error, since it allows an expression index using these operators to be
built even when not all values in the column are suitable for the
extraction being indexed.  Moreover, we already had multiple
inconsistencies between the path extraction operators and the simple
extraction operators, as well as inconsistencies between the JSON and
JSONB code paths.  Adopt a uniform rule of returning NULL rather than
throwing an error when the JSON input does not have a structure that
permits the request to be satisfied.

Back-patch to 9.4.  Update the release notes to list this as a behavior
change since 9.3.

6 files changed, 726 insertions, 86 deletions

diff --git a/src/test/regress/expected/json.out b/src/test/regress/expected/json.out
index b438e49bf9..bb4d9ed4be 100644
--- a/src/test/regress/expected/json.out
+++ b/src/test/regress/expected/json.out
@@ -506,11 +506,19 @@ INSERT INTO test_json VALUES
 SELECT test_json -> 'x'
 FROM test_json
 WHERE json_type = 'scalar';
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 'x'
 FROM test_json
 WHERE json_type = 'array';
-ERROR:  cannot extract field from a non-object
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 'x'
 FROM test_json
 WHERE json_type = 'object';
@@ -538,7 +546,11 @@ WHERE json_type = 'object';
 SELECT test_json -> 2
 FROM test_json
 WHERE json_type = 'scalar';
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 2
 FROM test_json
 WHERE json_type = 'array';
@@ -550,7 +562,11 @@ WHERE json_type = 'array';
 SELECT test_json -> 2
 FROM test_json
 WHERE json_type = 'object';
-ERROR:  cannot extract array element from a non-array
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json->>2
 FROM test_json
 WHERE json_type = 'array';
@@ -667,7 +683,11 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> null::int;
 (1 row)
 
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> 1;
-ERROR:  cannot extract array element from a non-array
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> 'z';
  ?column? 
 ----------
@@ -693,11 +713,29 @@ select '[{"b": "c"}, {"b": "cc"}]'::json -> 3;
 (1 row)
 
 select '[{"b": "c"}, {"b": "cc"}]'::json -> 'z';
-ERROR:  cannot extract field from a non-object
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": "c", "b": null}'::json -> 'b';
+ ?column? 
+----------
+ null
+(1 row)
+
 select '"foo"'::json -> 1;
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::json -> 'z';
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json ->> null::text;
  ?column? 
 ----------
@@ -711,7 +749,11 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json ->> null::int;
 (1 row)
 
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json ->> 1;
-ERROR:  cannot extract array element from a non-array
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json ->> 'z';
  ?column? 
 ----------
@@ -737,11 +779,29 @@ select '[{"b": "c"}, {"b": "cc"}]'::json ->> 3;
 (1 row)
 
 select '[{"b": "c"}, {"b": "cc"}]'::json ->> 'z';
-ERROR:  cannot extract field from a non-object
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": "c", "b": null}'::json ->> 'b';
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::json ->> 1;
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::json ->> 'z';
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 -- array length
 SELECT json_array_length('[1,2,3,{"f1":1,"f2":[5,6]},4]');
  json_array_length 
@@ -922,9 +982,33 @@ select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>array['f2','1'];
 
 -- corner cases for same
 select '{"a": {"b":{"c": "foo"}}}'::json #> '{}';
+         ?column?          
+---------------------------
+ {"a": {"b":{"c": "foo"}}}
+(1 row)
+
+select '[1,2,3]'::json #> '{}';
  ?column? 
 ----------
- 
+ [1,2,3]
+(1 row)
+
+select '"foo"'::json #> '{}';
+ ?column? 
+----------
+ "foo"
+(1 row)
+
+select '42'::json #> '{}';
+ ?column? 
+----------
+ 42
+(1 row)
+
+select 'null'::json #> '{}';
+ ?column? 
+----------
+ null
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a'];
@@ -934,9 +1018,17 @@ select '{"a": {"b":{"c": "foo"}}}'::json #> array['a'];
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a', null];
-ERROR:  cannot call json_extract_path with null path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a', ''];
-ERROR:  cannot call json_extract_path with empty path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b'];
    ?column?   
 --------------
@@ -985,6 +1077,12 @@ select '[{"b": "c"}, {"b": "cc"}]'::json #> array['z','b'];
  
 (1 row)
 
+select '[{"b": "c"}, {"b": null}]'::json #> array['1','b'];
+ ?column? 
+----------
+ null
+(1 row)
+
 select '"foo"'::json #> array['z'];
  ?column? 
 ----------
@@ -1004,6 +1102,30 @@ select '42'::json #> array['0'];
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::json #>> '{}';
+         ?column?          
+---------------------------
+ {"a": {"b":{"c": "foo"}}}
+(1 row)
+
+select '[1,2,3]'::json #>> '{}';
+ ?column? 
+----------
+ [1,2,3]
+(1 row)
+
+select '"foo"'::json #>> '{}';
+ ?column? 
+----------
+ foo
+(1 row)
+
+select '42'::json #>> '{}';
+ ?column? 
+----------
+ 42
+(1 row)
+
+select 'null'::json #>> '{}';
  ?column? 
 ----------
  
@@ -1016,9 +1138,17 @@ select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a'];
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a', null];
-ERROR:  cannot call json_extract_path_text with null path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a', ''];
-ERROR:  cannot call json_extract_path_text with empty path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b'];
    ?column?   
 --------------
@@ -1067,6 +1197,12 @@ select '[{"b": "c"}, {"b": "cc"}]'::json #>> array['z','b'];
  
 (1 row)
 
+select '[{"b": "c"}, {"b": null}]'::json #>> array['1','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::json #>> array['z'];
  ?column? 
 ----------
diff --git a/src/test/regress/expected/json_1.out b/src/test/regress/expected/json_1.out
index 077fcbd0ed..83c1d7d492 100644
--- a/src/test/regress/expected/json_1.out
+++ b/src/test/regress/expected/json_1.out
@@ -506,11 +506,19 @@ INSERT INTO test_json VALUES
 SELECT test_json -> 'x'
 FROM test_json
 WHERE json_type = 'scalar';
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 'x'
 FROM test_json
 WHERE json_type = 'array';
-ERROR:  cannot extract field from a non-object
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 'x'
 FROM test_json
 WHERE json_type = 'object';
@@ -538,7 +546,11 @@ WHERE json_type = 'object';
 SELECT test_json -> 2
 FROM test_json
 WHERE json_type = 'scalar';
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 2
 FROM test_json
 WHERE json_type = 'array';
@@ -550,7 +562,11 @@ WHERE json_type = 'array';
 SELECT test_json -> 2
 FROM test_json
 WHERE json_type = 'object';
-ERROR:  cannot extract array element from a non-array
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json->>2
 FROM test_json
 WHERE json_type = 'array';
@@ -667,7 +683,11 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> null::int;
 (1 row)
 
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> 1;
-ERROR:  cannot extract array element from a non-array
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> 'z';
  ?column? 
 ----------
@@ -693,11 +713,29 @@ select '[{"b": "c"}, {"b": "cc"}]'::json -> 3;
 (1 row)
 
 select '[{"b": "c"}, {"b": "cc"}]'::json -> 'z';
-ERROR:  cannot extract field from a non-object
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": "c", "b": null}'::json -> 'b';
+ ?column? 
+----------
+ null
+(1 row)
+
 select '"foo"'::json -> 1;
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::json -> 'z';
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json ->> null::text;
  ?column? 
 ----------
@@ -711,7 +749,11 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json ->> null::int;
 (1 row)
 
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json ->> 1;
-ERROR:  cannot extract array element from a non-array
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json ->> 'z';
  ?column? 
 ----------
@@ -737,11 +779,29 @@ select '[{"b": "c"}, {"b": "cc"}]'::json ->> 3;
 (1 row)
 
 select '[{"b": "c"}, {"b": "cc"}]'::json ->> 'z';
-ERROR:  cannot extract field from a non-object
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": "c", "b": null}'::json ->> 'b';
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::json ->> 1;
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::json ->> 'z';
-ERROR:  cannot extract element from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 -- array length
 SELECT json_array_length('[1,2,3,{"f1":1,"f2":[5,6]},4]');
  json_array_length 
@@ -922,9 +982,33 @@ select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>array['f2','1'];
 
 -- corner cases for same
 select '{"a": {"b":{"c": "foo"}}}'::json #> '{}';
+         ?column?          
+---------------------------
+ {"a": {"b":{"c": "foo"}}}
+(1 row)
+
+select '[1,2,3]'::json #> '{}';
  ?column? 
 ----------
- 
+ [1,2,3]
+(1 row)
+
+select '"foo"'::json #> '{}';
+ ?column? 
+----------
+ "foo"
+(1 row)
+
+select '42'::json #> '{}';
+ ?column? 
+----------
+ 42
+(1 row)
+
+select 'null'::json #> '{}';
+ ?column? 
+----------
+ null
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a'];
@@ -934,9 +1018,17 @@ select '{"a": {"b":{"c": "foo"}}}'::json #> array['a'];
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a', null];
-ERROR:  cannot call json_extract_path with null path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a', ''];
-ERROR:  cannot call json_extract_path with empty path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a','b'];
    ?column?   
 --------------
@@ -985,6 +1077,12 @@ select '[{"b": "c"}, {"b": "cc"}]'::json #> array['z','b'];
  
 (1 row)
 
+select '[{"b": "c"}, {"b": null}]'::json #> array['1','b'];
+ ?column? 
+----------
+ null
+(1 row)
+
 select '"foo"'::json #> array['z'];
  ?column? 
 ----------
@@ -1004,6 +1102,30 @@ select '42'::json #> array['0'];
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::json #>> '{}';
+         ?column?          
+---------------------------
+ {"a": {"b":{"c": "foo"}}}
+(1 row)
+
+select '[1,2,3]'::json #>> '{}';
+ ?column? 
+----------
+ [1,2,3]
+(1 row)
+
+select '"foo"'::json #>> '{}';
+ ?column? 
+----------
+ foo
+(1 row)
+
+select '42'::json #>> '{}';
+ ?column? 
+----------
+ 42
+(1 row)
+
+select 'null'::json #>> '{}';
  ?column? 
 ----------
  
@@ -1016,9 +1138,17 @@ select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a'];
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a', null];
-ERROR:  cannot call json_extract_path_text with null path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a', ''];
-ERROR:  cannot call json_extract_path_text with empty path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a','b'];
    ?column?   
 --------------
@@ -1067,6 +1197,12 @@ select '[{"b": "c"}, {"b": "cc"}]'::json #>> array['z','b'];
  
 (1 row)
 
+select '[{"b": "c"}, {"b": null}]'::json #>> array['1','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::json #>> array['z'];
  ?column? 
 ----------
diff --git a/src/test/regress/expected/jsonb.out b/src/test/regress/expected/jsonb.out
index ea4d6e1f4c..eb37da7168 100644
--- a/src/test/regress/expected/jsonb.out
+++ b/src/test/regress/expected/jsonb.out
@@ -311,9 +311,17 @@ INSERT INTO test_jsonb VALUES
 ('array','["zero", "one","two",null,"four","five", [1,2,3],{"f1":9}]'),
 ('object','{"field1":"val1","field2":"val2","field3":null, "field4": 4, "field5": [1,2,3], "field6": {"f1":9}}');
 SELECT test_json -> 'x' FROM test_jsonb WHERE json_type = 'scalar';
-ERROR:  cannot call jsonb_object_field (jsonb -> text) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 'x' FROM test_jsonb WHERE json_type = 'array';
-ERROR:  cannot call jsonb_object_field (jsonb -> text) on an array
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 'x' FROM test_jsonb WHERE json_type = 'object';
  ?column? 
 ----------
@@ -327,9 +335,17 @@ SELECT test_json -> 'field2' FROM test_jsonb WHERE json_type = 'object';
 (1 row)
 
 SELECT test_json ->> 'field2' FROM test_jsonb WHERE json_type = 'scalar';
-ERROR:  cannot call jsonb_object_field_text (jsonb ->> text) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json ->> 'field2' FROM test_jsonb WHERE json_type = 'array';
-ERROR:  cannot call jsonb_object_field_text (jsonb ->> text) on an array
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json ->> 'field2' FROM test_jsonb WHERE json_type = 'object';
  ?column? 
 ----------
@@ -337,7 +353,11 @@ SELECT test_json ->> 'field2' FROM test_jsonb WHERE json_type = 'object';
 (1 row)
 
 SELECT test_json -> 2 FROM test_jsonb WHERE json_type = 'scalar';
-ERROR:  cannot call jsonb_array_element (jsonb -> int) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 2 FROM test_jsonb WHERE json_type = 'array';
  ?column? 
 ----------
@@ -351,7 +371,11 @@ SELECT test_json -> 9 FROM test_jsonb WHERE json_type = 'array';
 (1 row)
 
 SELECT test_json -> 2 FROM test_jsonb WHERE json_type = 'object';
-ERROR:  cannot call jsonb_array_element (jsonb -> int) on an object
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json ->> 6 FROM test_jsonb WHERE json_type = 'array';
  ?column?  
 -----------
@@ -383,7 +407,11 @@ SELECT test_json ->> 'field6' FROM test_jsonb WHERE json_type = 'object';
 (1 row)
 
 SELECT test_json ->> 2 FROM test_jsonb WHERE json_type = 'scalar';
-ERROR:  cannot call jsonb_array_element_text on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json ->> 2 FROM test_jsonb WHERE json_type = 'array';
  ?column? 
 ----------
@@ -391,7 +419,11 @@ SELECT test_json ->> 2 FROM test_jsonb WHERE json_type = 'array';
 (1 row)
 
 SELECT test_json ->> 2 FROM test_jsonb WHERE json_type = 'object';
-ERROR:  cannot call jsonb_array_element_text on an object
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT jsonb_object_keys(test_json) FROM test_jsonb WHERE json_type = 'scalar';
 ERROR:  cannot call jsonb_object_keys on a scalar
 SELECT jsonb_object_keys(test_json) FROM test_jsonb WHERE json_type = 'array';
@@ -446,7 +478,11 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> null::int;
 (1 row)
 
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> 1;
-ERROR:  cannot call jsonb_array_element (jsonb -> int) on an object
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> 'z';
  ?column? 
 ----------
@@ -472,11 +508,29 @@ select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 3;
 (1 row)
 
 select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 'z';
-ERROR:  cannot call jsonb_object_field (jsonb -> text) on an array
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": "c", "b": null}'::jsonb -> 'b';
+ ?column? 
+----------
+ null
+(1 row)
+
 select '"foo"'::jsonb -> 1;
-ERROR:  cannot call jsonb_array_element (jsonb -> int) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::jsonb -> 'z';
-ERROR:  cannot call jsonb_object_field (jsonb -> text) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb ->> null::text;
  ?column? 
 ----------
@@ -490,7 +544,11 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb ->> null::int;
 (1 row)
 
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb ->> 1;
-ERROR:  cannot call jsonb_array_element_text on an object
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb ->> 'z';
  ?column? 
 ----------
@@ -516,11 +574,29 @@ select '[{"b": "c"}, {"b": "cc"}]'::jsonb ->> 3;
 (1 row)
 
 select '[{"b": "c"}, {"b": "cc"}]'::jsonb ->> 'z';
-ERROR:  cannot call jsonb_object_field_text (jsonb ->> text) on an array
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": "c", "b": null}'::jsonb ->> 'b';
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::jsonb ->> 1;
-ERROR:  cannot call jsonb_array_element_text on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::jsonb ->> 'z';
-ERROR:  cannot call jsonb_object_field_text (jsonb ->> text) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 -- equality and inequality
 SELECT '{"x":"y"}'::jsonb = '{"x":"y"}'::jsonb;
  ?column? 
@@ -1269,9 +1345,33 @@ SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>array['f2','1'];
 
 -- corner cases for same
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> '{}';
+          ?column?          
+----------------------------
+ {"a": {"b": {"c": "foo"}}}
+(1 row)
+
+select '[1,2,3]'::jsonb #> '{}';
+ ?column?  
+-----------
+ [1, 2, 3]
+(1 row)
+
+select '"foo"'::jsonb #> '{}';
  ?column? 
 ----------
- 
+ "foo"
+(1 row)
+
+select '42'::jsonb #> '{}';
+ ?column? 
+----------
+ 42
+(1 row)
+
+select 'null'::jsonb #> '{}';
+ ?column? 
+----------
+ null
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a'];
@@ -1281,7 +1381,11 @@ select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a'];
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a', null];
-ERROR:  cannot call jsonb_extract_path with null path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a', ''];
  ?column? 
 ----------
@@ -1336,13 +1440,55 @@ select '[{"b": "c"}, {"b": "cc"}]'::jsonb #> array['z','b'];
  
 (1 row)
 
+select '[{"b": "c"}, {"b": null}]'::jsonb #> array['1','b'];
+ ?column? 
+----------
+ null
+(1 row)
+
 select '"foo"'::jsonb #> array['z'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '42'::jsonb #> array['f2'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '42'::jsonb #> array['0'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> '{}';
+          ?column?          
+----------------------------
+ {"a": {"b": {"c": "foo"}}}
+(1 row)
+
+select '[1,2,3]'::jsonb #>> '{}';
+ ?column?  
+-----------
+ [1, 2, 3]
+(1 row)
+
+select '"foo"'::jsonb #>> '{}';
+ ?column? 
+----------
+ foo
+(1 row)
+
+select '42'::jsonb #>> '{}';
+ ?column? 
+----------
+ 42
+(1 row)
+
+select 'null'::jsonb #>> '{}';
  ?column? 
 ----------
  
@@ -1355,7 +1501,11 @@ select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a'];
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a', null];
-ERROR:  cannot call jsonb_extract_path_text with null path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a', ''];
  ?column? 
 ----------
@@ -1410,12 +1560,30 @@ select '[{"b": "c"}, {"b": "cc"}]'::jsonb #>> array['z','b'];
  
 (1 row)
 
+select '[{"b": "c"}, {"b": null}]'::jsonb #>> array['1','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::jsonb #>> array['z'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '42'::jsonb #>> array['f2'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '42'::jsonb #>> array['0'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 -- array_elements
 SELECT jsonb_array_elements('[1,true,[1,[2,3]],null,{"f1":1,"f2":[7,8,9]},false]');
     jsonb_array_elements    
@@ -2105,7 +2273,11 @@ SELECT '{"n":null,"a":1,"b":[1,2],"c":{"1":2},"d":{"1":[2,3]}}'::jsonb -> 'e';
 (1 row)
 
 SELECT '{"n":null,"a":1,"b":[1,2],"c":{"1":2},"d":{"1":[2,3]}}'::jsonb -> 0; --expecting error
-ERROR:  cannot call jsonb_array_element (jsonb -> int) on an object
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT '["a","b","c",[1,2],null]'::jsonb -> 0;
  ?column? 
 ----------
diff --git a/src/test/regress/expected/jsonb_1.out b/src/test/regress/expected/jsonb_1.out
index 4c2d5ae0b3..f3bfc7bcf5 100644
--- a/src/test/regress/expected/jsonb_1.out
+++ b/src/test/regress/expected/jsonb_1.out
@@ -311,9 +311,17 @@ INSERT INTO test_jsonb VALUES
 ('array','["zero", "one","two",null,"four","five", [1,2,3],{"f1":9}]'),
 ('object','{"field1":"val1","field2":"val2","field3":null, "field4": 4, "field5": [1,2,3], "field6": {"f1":9}}');
 SELECT test_json -> 'x' FROM test_jsonb WHERE json_type = 'scalar';
-ERROR:  cannot call jsonb_object_field (jsonb -> text) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 'x' FROM test_jsonb WHERE json_type = 'array';
-ERROR:  cannot call jsonb_object_field (jsonb -> text) on an array
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 'x' FROM test_jsonb WHERE json_type = 'object';
  ?column? 
 ----------
@@ -327,9 +335,17 @@ SELECT test_json -> 'field2' FROM test_jsonb WHERE json_type = 'object';
 (1 row)
 
 SELECT test_json ->> 'field2' FROM test_jsonb WHERE json_type = 'scalar';
-ERROR:  cannot call jsonb_object_field_text (jsonb ->> text) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json ->> 'field2' FROM test_jsonb WHERE json_type = 'array';
-ERROR:  cannot call jsonb_object_field_text (jsonb ->> text) on an array
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json ->> 'field2' FROM test_jsonb WHERE json_type = 'object';
  ?column? 
 ----------
@@ -337,7 +353,11 @@ SELECT test_json ->> 'field2' FROM test_jsonb WHERE json_type = 'object';
 (1 row)
 
 SELECT test_json -> 2 FROM test_jsonb WHERE json_type = 'scalar';
-ERROR:  cannot call jsonb_array_element (jsonb -> int) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json -> 2 FROM test_jsonb WHERE json_type = 'array';
  ?column? 
 ----------
@@ -351,7 +371,11 @@ SELECT test_json -> 9 FROM test_jsonb WHERE json_type = 'array';
 (1 row)
 
 SELECT test_json -> 2 FROM test_jsonb WHERE json_type = 'object';
-ERROR:  cannot call jsonb_array_element (jsonb -> int) on an object
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json ->> 6 FROM test_jsonb WHERE json_type = 'array';
  ?column?  
 -----------
@@ -383,7 +407,11 @@ SELECT test_json ->> 'field6' FROM test_jsonb WHERE json_type = 'object';
 (1 row)
 
 SELECT test_json ->> 2 FROM test_jsonb WHERE json_type = 'scalar';
-ERROR:  cannot call jsonb_array_element_text on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT test_json ->> 2 FROM test_jsonb WHERE json_type = 'array';
  ?column? 
 ----------
@@ -391,7 +419,11 @@ SELECT test_json ->> 2 FROM test_jsonb WHERE json_type = 'array';
 (1 row)
 
 SELECT test_json ->> 2 FROM test_jsonb WHERE json_type = 'object';
-ERROR:  cannot call jsonb_array_element_text on an object
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT jsonb_object_keys(test_json) FROM test_jsonb WHERE json_type = 'scalar';
 ERROR:  cannot call jsonb_object_keys on a scalar
 SELECT jsonb_object_keys(test_json) FROM test_jsonb WHERE json_type = 'array';
@@ -446,7 +478,11 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> null::int;
 (1 row)
 
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> 1;
-ERROR:  cannot call jsonb_array_element (jsonb -> int) on an object
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> 'z';
  ?column? 
 ----------
@@ -472,11 +508,29 @@ select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 3;
 (1 row)
 
 select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 'z';
-ERROR:  cannot call jsonb_object_field (jsonb -> text) on an array
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": "c", "b": null}'::jsonb -> 'b';
+ ?column? 
+----------
+ null
+(1 row)
+
 select '"foo"'::jsonb -> 1;
-ERROR:  cannot call jsonb_array_element (jsonb -> int) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::jsonb -> 'z';
-ERROR:  cannot call jsonb_object_field (jsonb -> text) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb ->> null::text;
  ?column? 
 ----------
@@ -490,7 +544,11 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb ->> null::int;
 (1 row)
 
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb ->> 1;
-ERROR:  cannot call jsonb_array_element_text on an object
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb ->> 'z';
  ?column? 
 ----------
@@ -516,11 +574,29 @@ select '[{"b": "c"}, {"b": "cc"}]'::jsonb ->> 3;
 (1 row)
 
 select '[{"b": "c"}, {"b": "cc"}]'::jsonb ->> 'z';
-ERROR:  cannot call jsonb_object_field_text (jsonb ->> text) on an array
+ ?column? 
+----------
+ 
+(1 row)
+
+select '{"a": "c", "b": null}'::jsonb ->> 'b';
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::jsonb ->> 1;
-ERROR:  cannot call jsonb_array_element_text on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::jsonb ->> 'z';
-ERROR:  cannot call jsonb_object_field_text (jsonb ->> text) on a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 -- equality and inequality
 SELECT '{"x":"y"}'::jsonb = '{"x":"y"}'::jsonb;
  ?column? 
@@ -1269,9 +1345,33 @@ SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>array['f2','1'];
 
 -- corner cases for same
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> '{}';
+          ?column?          
+----------------------------
+ {"a": {"b": {"c": "foo"}}}
+(1 row)
+
+select '[1,2,3]'::jsonb #> '{}';
+ ?column?  
+-----------
+ [1, 2, 3]
+(1 row)
+
+select '"foo"'::jsonb #> '{}';
  ?column? 
 ----------
- 
+ "foo"
+(1 row)
+
+select '42'::jsonb #> '{}';
+ ?column? 
+----------
+ 42
+(1 row)
+
+select 'null'::jsonb #> '{}';
+ ?column? 
+----------
+ null
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a'];
@@ -1281,7 +1381,11 @@ select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a'];
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a', null];
-ERROR:  cannot call jsonb_extract_path with null path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a', ''];
  ?column? 
 ----------
@@ -1336,13 +1440,55 @@ select '[{"b": "c"}, {"b": "cc"}]'::jsonb #> array['z','b'];
  
 (1 row)
 
+select '[{"b": "c"}, {"b": null}]'::jsonb #> array['1','b'];
+ ?column? 
+----------
+ null
+(1 row)
+
 select '"foo"'::jsonb #> array['z'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '42'::jsonb #> array['f2'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '42'::jsonb #> array['0'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> '{}';
+          ?column?          
+----------------------------
+ {"a": {"b": {"c": "foo"}}}
+(1 row)
+
+select '[1,2,3]'::jsonb #>> '{}';
+ ?column?  
+-----------
+ [1, 2, 3]
+(1 row)
+
+select '"foo"'::jsonb #>> '{}';
+ ?column? 
+----------
+ foo
+(1 row)
+
+select '42'::jsonb #>> '{}';
+ ?column? 
+----------
+ 42
+(1 row)
+
+select 'null'::jsonb #>> '{}';
  ?column? 
 ----------
  
@@ -1355,7 +1501,11 @@ select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a'];
 (1 row)
 
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a', null];
-ERROR:  cannot call jsonb_extract_path_text with null path elements
+ ?column? 
+----------
+ 
+(1 row)
+
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a', ''];
  ?column? 
 ----------
@@ -1410,12 +1560,30 @@ select '[{"b": "c"}, {"b": "cc"}]'::jsonb #>> array['z','b'];
  
 (1 row)
 
+select '[{"b": "c"}, {"b": null}]'::jsonb #>> array['1','b'];
+ ?column? 
+----------
+ 
+(1 row)
+
 select '"foo"'::jsonb #>> array['z'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '42'::jsonb #>> array['f2'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 select '42'::jsonb #>> array['0'];
-ERROR:  cannot extract path from a scalar
+ ?column? 
+----------
+ 
+(1 row)
+
 -- array_elements
 SELECT jsonb_array_elements('[1,true,[1,[2,3]],null,{"f1":1,"f2":[7,8,9]},false]');
     jsonb_array_elements    
@@ -2105,7 +2273,11 @@ SELECT '{"n":null,"a":1,"b":[1,2],"c":{"1":2},"d":{"1":[2,3]}}'::jsonb -> 'e';
 (1 row)
 
 SELECT '{"n":null,"a":1,"b":[1,2],"c":{"1":2},"d":{"1":[2,3]}}'::jsonb -> 0; --expecting error
-ERROR:  cannot call jsonb_array_element (jsonb -> int) on an object
+ ?column? 
+----------
+ 
+(1 row)
+
 SELECT '["a","b","c",[1,2],null]'::jsonb -> 0;
  ?column? 
 ----------
diff --git a/src/test/regress/sql/json.sql b/src/test/regress/sql/json.sql
index 4db5547401..c9801321e0 100644
--- a/src/test/regress/sql/json.sql
+++ b/src/test/regress/sql/json.sql
@@ -248,6 +248,7 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json -> '';
 select '[{"b": "c"}, {"b": "cc"}]'::json -> 1;
 select '[{"b": "c"}, {"b": "cc"}]'::json -> 3;
 select '[{"b": "c"}, {"b": "cc"}]'::json -> 'z';
+select '{"a": "c", "b": null}'::json -> 'b';
 select '"foo"'::json -> 1;
 select '"foo"'::json -> 'z';
 
@@ -259,6 +260,7 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::json ->> '';
 select '[{"b": "c"}, {"b": "cc"}]'::json ->> 1;
 select '[{"b": "c"}, {"b": "cc"}]'::json ->> 3;
 select '[{"b": "c"}, {"b": "cc"}]'::json ->> 'z';
+select '{"a": "c", "b": null}'::json ->> 'b';
 select '"foo"'::json ->> 1;
 select '"foo"'::json ->> 'z';
 
@@ -312,6 +314,10 @@ select '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::json#>>array['f2','1'];
 
 -- corner cases for same
 select '{"a": {"b":{"c": "foo"}}}'::json #> '{}';
+select '[1,2,3]'::json #> '{}';
+select '"foo"'::json #> '{}';
+select '42'::json #> '{}';
+select 'null'::json #> '{}';
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a'];
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a', null];
 select '{"a": {"b":{"c": "foo"}}}'::json #> array['a', ''];
@@ -323,11 +329,16 @@ 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 '[{"b": "c"}, {"b": null}]'::json #> array['1','b'];
 select '"foo"'::json #> array['z'];
 select '42'::json #> array['f2'];
 select '42'::json #> array['0'];
 
 select '{"a": {"b":{"c": "foo"}}}'::json #>> '{}';
+select '[1,2,3]'::json #>> '{}';
+select '"foo"'::json #>> '{}';
+select '42'::json #>> '{}';
+select 'null'::json #>> '{}';
 select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a'];
 select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a', null];
 select '{"a": {"b":{"c": "foo"}}}'::json #>> array['a', ''];
@@ -339,6 +350,7 @@ 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 '[{"b": "c"}, {"b": null}]'::json #>> array['1','b'];
 select '"foo"'::json #>> array['z'];
 select '42'::json #>> array['f2'];
 select '42'::json #>> array['0'];
diff --git a/src/test/regress/sql/jsonb.sql b/src/test/regress/sql/jsonb.sql
index 141dda9508..ed266d5c88 100644
--- a/src/test/regress/sql/jsonb.sql
+++ b/src/test/regress/sql/jsonb.sql
@@ -117,6 +117,7 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb -> '';
 select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 1;
 select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 3;
 select '[{"b": "c"}, {"b": "cc"}]'::jsonb -> 'z';
+select '{"a": "c", "b": null}'::jsonb -> 'b';
 select '"foo"'::jsonb -> 1;
 select '"foo"'::jsonb -> 'z';
 
@@ -128,6 +129,7 @@ select '{"a": [{"b": "c"}, {"b": "cc"}]}'::jsonb ->> '';
 select '[{"b": "c"}, {"b": "cc"}]'::jsonb ->> 1;
 select '[{"b": "c"}, {"b": "cc"}]'::jsonb ->> 3;
 select '[{"b": "c"}, {"b": "cc"}]'::jsonb ->> 'z';
+select '{"a": "c", "b": null}'::jsonb ->> 'b';
 select '"foo"'::jsonb ->> 1;
 select '"foo"'::jsonb ->> 'z';
 
@@ -283,6 +285,10 @@ SELECT '{"f2":["f3",1],"f4":{"f5":99,"f6":"stringy"}}'::jsonb#>>array['f2','1'];
 
 -- corner cases for same
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> '{}';
+select '[1,2,3]'::jsonb #> '{}';
+select '"foo"'::jsonb #> '{}';
+select '42'::jsonb #> '{}';
+select 'null'::jsonb #> '{}';
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a'];
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a', null];
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #> array['a', ''];
@@ -294,11 +300,16 @@ 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 '[{"b": "c"}, {"b": null}]'::jsonb #> array['1','b'];
 select '"foo"'::jsonb #> array['z'];
 select '42'::jsonb #> array['f2'];
 select '42'::jsonb #> array['0'];
 
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> '{}';
+select '[1,2,3]'::jsonb #>> '{}';
+select '"foo"'::jsonb #>> '{}';
+select '42'::jsonb #>> '{}';
+select 'null'::jsonb #>> '{}';
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a'];
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a', null];
 select '{"a": {"b":{"c": "foo"}}}'::jsonb #>> array['a', ''];
@@ -310,6 +321,7 @@ 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 '[{"b": "c"}, {"b": null}]'::jsonb #>> array['1','b'];
 select '"foo"'::jsonb #>> array['z'];
 select '42'::jsonb #>> array['f2'];
 select '42'::jsonb #>> array['0'];