diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index 6a7aab2..bac08c0 100644
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -42,6 +42,8 @@
 #define JB_PATH_CREATE_OR_INSERT \
 	(JB_PATH_INSERT_BEFORE | JB_PATH_INSERT_AFTER | JB_PATH_CREATE)

+#define is_jsonb_data(type) (type == WJB_KEY || type == WJB_VALUE || type == WJB_ELEM)
+
 /* state for json_object_keys */
 typedef struct OkeysState
 {
@@ -52,6 +54,23 @@ typedef struct OkeysState
 	int			sent_count;
 } OkeysState;

+/* state for iterate_json function */
+typedef struct IterateJsonState
+{
+	JsonLexContext		*lex;
+	JsonIterateAction	action;			/* an action that will be applied to each json value */
+	void				*action_state;	/* any necessary context for iteration */
+} IterateJsonState;
+
+/* state for transform_json function */
+typedef struct TransformJsonState
+{
+	JsonLexContext		*lex;
+	StringInfo			strval;			/* resulting json */
+	JsonTransformAction	action;			/* an action that will be applied to each json value */
+	void				*action_state;	/* any necessary context for transformation */
+} TransformJsonState;
+
 /* state for json_get* functions */
 typedef struct GetState
 {
@@ -271,6 +290,18 @@ static void setPathArray(JsonbIterator **it, Datum *path_elems,
 			 int level, Jsonb *newval, uint32 nelems, int op_type);
 static void addJsonbToParseState(JsonbParseState **jbps, Jsonb *jb);

+/* function supporting iterate_json(b) */
+static void apply_action(void *state, char *token, JsonTokenType tokentype);
+
+/* function supporting transform_json(b) */
+static void transform_object_start(void *state);
+static void transform_object_end(void *state);
+static void transform_array_start(void *state);
+static void transform_array_end(void *state);
+static void transform_object_field_start(void *state, char *fname, bool isnull);
+static void transform_array_element_start(void *state, bool isnull);
+static void transform_scalar(void *state, char *token, JsonTokenType tokentype);
+

 /*
  * SQL function json_object_keys
@@ -4130,3 +4161,206 @@ setPathArray(JsonbIterator **it, Datum *path_elems, bool *path_nulls,
 		}
 	}
 }
+
+/*
+ * Iterate over jsonb string values or elements, and pass them together with
+ * an iteration state to a specified JsonIterateAction.
+ */
+void *
+iterate_jsonb_values(Jsonb *jb, void *state, JsonIterateAction action)
+{
+	JsonbIterator		*it;
+	JsonbValue			v;
+	JsonbIteratorToken	type;
+
+	it = JsonbIteratorInit(&jb->root);
+
+	while ((type = JsonbIteratorNext(&it, &v, false)) != WJB_DONE)
+	{
+		if ((type == WJB_VALUE || type == WJB_ELEM) && v.type == jbvString)
+		{
+			action(state, v.val.string.val, v.val.string.len);
+		}
+	}
+
+	return state;
+}
+
+/*
+ * Iterate over json string values or elements, and pass them together with an
+ * iteration state to a specified JsonIterateAction.
+ */
+void *
+iterate_json_values(text *json, void *action_state, JsonIterateAction action)
+{
+	JsonLexContext *lex = makeJsonLexContext(json, true);
+	JsonSemAction *sem = palloc0(sizeof(JsonSemAction));
+	IterateJsonState   *state = palloc0(sizeof(IterateJsonState));
+
+	state->lex = lex;
+	state->action = action;
+	state->action_state = action_state;
+
+	sem->semstate = (void *) state;
+	sem->scalar = apply_action;
+
+	pg_parse_json(lex, sem);
+
+	return state;
+}
+
+/*
+ * An auxiliary function for iterate_json_values to invoke a specified
+ * JsonIterateAction.
+ */
+static void
+apply_action(void *state, char *token, JsonTokenType tokentype)
+{
+	IterateJsonState   *_state = (IterateJsonState *) state;
+	if (tokentype == JSON_TOKEN_STRING)
+		(*_state->action) (_state->action_state, token, strlen(token));
+}
+
+/*
+ * Iterate over a jsonb, and apply a specified JsonTransformAction to every
+ * string value or element. Any necessary context for a JsonTransformAction can
+ * be passed in the action_state variable. Function returns a copy of an original jsonb
+ * object with transformed values.
+ */
+Jsonb *
+transform_jsonb(Jsonb *jsonb, void *action_state, JsonTransformAction transform_action)
+{
+	JsonbIterator		*it;
+	JsonbValue			v, *res = NULL;
+	JsonbIteratorToken	type;
+	JsonbParseState		*st = NULL;
+	text				*out;
+	bool				is_scalar = false;
+
+	it = JsonbIteratorInit(&jsonb->root);
+	is_scalar = it->isScalar;
+
+	while ((type = JsonbIteratorNext(&it, &v, false)) != WJB_DONE)
+	{
+		if ((type == WJB_VALUE || type == WJB_ELEM) && v.type == jbvString)
+		{
+			out = transform_action(action_state, v.val.string.val, v.val.string.len);
+			v.val.string.val = VARDATA_ANY(out);
+			v.val.string.len = VARSIZE_ANY_EXHDR(out);
+			res = pushJsonbValue(&st, type, type < WJB_BEGIN_ARRAY ? &v : NULL);
+		}
+		else
+		{
+			res = pushJsonbValue(&st, type, is_jsonb_data(type) ? &v : NULL);
+		}
+	}
+
+	if (res->type == jbvArray)
+		res->val.array.rawScalar = is_scalar;
+
+	return JsonbValueToJsonb(res);
+}
+
+/*
+ * Iterate over a json, and apply a specified JsonTransformAction to every
+ * string value or element. Any necessary context for a JsonTransformAction can
+ * be passed in the action_state variable. Function returns a StringInfo, which
+ * is a copy of an original json with transformed values.
+ */
+StringInfo
+transform_json(text *json, void *action_state, JsonTransformAction transform_action)
+{
+	JsonLexContext *lex = makeJsonLexContext(json, true);
+	JsonSemAction *sem = palloc0(sizeof(JsonSemAction));
+	TransformJsonState *state = palloc0(sizeof(TransformJsonState));
+
+	state->lex = lex;
+	state->strval = makeStringInfo();
+	state->action = transform_action;
+	state->action_state = action_state;
+
+	sem->semstate = (void *) state;
+	sem->scalar = transform_scalar;
+	sem->object_start = transform_object_start;
+	sem->object_end = transform_object_end;
+	sem->array_start = transform_array_start;
+	sem->array_end = transform_array_end;
+	sem->scalar = transform_scalar;
+	sem->array_element_start = transform_array_element_start;
+	sem->object_field_start = transform_object_field_start;
+
+	pg_parse_json(lex, sem);
+
+	return state->strval;
+}
+
+/*
+ * Set of auxiliary functions for transform_json to invoke a specified
+ * JsonTransformAction for all values and left everything else untouched.
+ */
+static void
+transform_object_start(void *state)
+{
+	TransformJsonState *_state = (TransformJsonState *) state;
+	appendStringInfoCharMacro(_state->strval, '{');
+}
+
+static void
+transform_object_end(void *state)
+{
+	TransformJsonState *_state = (TransformJsonState *) state;
+	appendStringInfoCharMacro(_state->strval, '}');
+}
+
+static void
+transform_array_start(void *state)
+{
+	TransformJsonState *_state = (TransformJsonState *) state;
+	appendStringInfoCharMacro(_state->strval, '[');
+}
+
+static void
+transform_array_end(void *state)
+{
+	TransformJsonState *_state = (TransformJsonState *) state;
+	appendStringInfoCharMacro(_state->strval, ']');
+}
+
+static void
+transform_object_field_start(void *state, char *fname, bool isnull)
+{
+	TransformJsonState *_state = (TransformJsonState *) state;
+
+	if (_state->strval->data[_state->strval->len - 1] != '{')
+		appendStringInfoCharMacro(_state->strval, ',');
+
+	/*
+	 * Unfortunately we don't have the quoted and escaped string any more, so
+	 * we have to re-escape it.
+	 */
+	escape_json(_state->strval, fname);
+	appendStringInfoCharMacro(_state->strval, ':');
+}
+
+static void
+transform_array_element_start(void *state, bool isnull)
+{
+	TransformJsonState *_state = (TransformJsonState *) state;
+
+	if (_state->strval->data[_state->strval->len - 1] != '[')
+		appendStringInfoCharMacro(_state->strval, ',');
+}
+
+static void
+transform_scalar(void *state, char *token, JsonTokenType tokentype)
+{
+	TransformJsonState *_state = (TransformJsonState *) state;
+
+	if (tokentype == JSON_TOKEN_STRING)
+	{
+		text *out = (*_state->action) (_state->action_state, token, strlen(token));
+		escape_json(_state->strval, text_to_cstring(out));
+	}
+	else
+		appendStringInfoString(_state->strval, token);
+}
diff --git a/src/include/utils/jsonb.h b/src/include/utils/jsonb.h
index 411e158..bf3de44 100644
--- a/src/include/utils/jsonb.h
+++ b/src/include/utils/jsonb.h
@@ -351,6 +351,12 @@ typedef struct JsonbIterator
 	struct JsonbIterator *parent;
 } JsonbIterator;

+/* an action that will be applied to each value in iterate_json(b) functions */
+typedef void (*JsonIterateAction) (void *state, char *elem_value, int elem_len);
+
+/* an action that will be applied to each value in transform_json(b) functions */
+typedef text * (*JsonTransformAction) (void *state, char *elem_value, int elem_len);
+

 /* Support functions */
 extern uint32 getJsonbOffset(const JsonbContainer *jc, int index);
@@ -377,5 +383,12 @@ extern char *JsonbToCString(StringInfo out, JsonbContainer *in,
 extern char *JsonbToCStringIndent(StringInfo out, JsonbContainer *in,
 					 int estimated_len);

+extern void *iterate_jsonb_values(Jsonb *jb, void *state, JsonIterateAction action);
+extern void *iterate_json_values(text *json, void *action_state, JsonIterateAction action);
+extern Jsonb *transform_jsonb(Jsonb *jsonb, void *action_state,
+						JsonTransformAction transform_action);
+extern StringInfo transform_json(text *json, void *action_state,
+							JsonTransformAction transform_action);
+

 #endif   /* __JSONB_H__ */