PLAN clauses for JSON_TABLE

These clauses allow the user to specify how data from nested paths are
joined, allowing considerable freedom in shaping the tabular output of
JSON_TABLE.

PLAN DEFAULT allows the user to specify the global strategies when
dealing with sibling or child nested paths. The is often sufficient to
achieve the necessary goal, and is considerably simpler than the full
PLAN clause, which allows the user to specify the strategy to be used
for each named nested path.

Nikita Glukhov

Reviewers have included (in no particular order) Andres Freund, Alexander
Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zhihong Yu,
Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby.

Discussion: https://postgr.es/m/7e2cb85d-24cf-4abb-30a5-1a33715959bd@postgrespro.ru

src/backend/nodes/copyfuncs.c

@@ -2696,6 +2696,7 @@ _copyJsonTable(const JsonTable *from)
 
 	COPY_NODE_FIELD(common);
 	COPY_NODE_FIELD(columns);
+	COPY_NODE_FIELD(plan);
 	COPY_NODE_FIELD(on_error);
 	COPY_NODE_FIELD(alias);
 	COPY_SCALAR_FIELD(location);
@@ -2715,6 +2716,7 @@ _copyJsonTableColumn(const JsonTableColumn *from)
 	COPY_STRING_FIELD(name);
 	COPY_NODE_FIELD(typeName);
 	COPY_STRING_FIELD(pathspec);
+	COPY_STRING_FIELD(pathname);
 	COPY_SCALAR_FIELD(format);
 	COPY_SCALAR_FIELD(wrapper);
 	COPY_SCALAR_FIELD(omit_quotes);
@@ -2726,6 +2728,24 @@ _copyJsonTableColumn(const JsonTableColumn *from)
 	return newnode;
 }
 
+/*
+ * _copyJsonTablePlan
+ */
+static JsonTablePlan *
+_copyJsonTablePlan(const JsonTablePlan *from)
+{
+	JsonTablePlan *newnode = makeNode(JsonTablePlan);
+
+	COPY_SCALAR_FIELD(plan_type);
+	COPY_SCALAR_FIELD(join_type);
+	COPY_STRING_FIELD(pathname);
+	COPY_NODE_FIELD(plan1);
+	COPY_NODE_FIELD(plan2);
+	COPY_SCALAR_FIELD(location);
+
+	return newnode;
+}
+
 /*
  * _copyJsonTableParent
  */
@@ -2735,7 +2755,9 @@ _copyJsonTableParent(const JsonTableParent *from)
 	JsonTableParent *newnode = makeNode(JsonTableParent);
 
 	COPY_NODE_FIELD(path);
+	COPY_STRING_FIELD(name);
 	COPY_NODE_FIELD(child);
+	COPY_SCALAR_FIELD(outerJoin);
 	COPY_SCALAR_FIELD(colMin);
 	COPY_SCALAR_FIELD(colMax);
 
@@ -2752,6 +2774,7 @@ _copyJsonTableSibling(const JsonTableSibling *from)
 
 	COPY_NODE_FIELD(larg);
 	COPY_NODE_FIELD(rarg);
+	COPY_SCALAR_FIELD(cross);
 
 	return newnode;
 }
@@ -5929,6 +5952,9 @@ copyObjectImpl(const void *from)
 		case T_JsonTableColumn:
 			retval = _copyJsonTableColumn(from);
 			break;
+		case T_JsonTablePlan:
+			retval = _copyJsonTablePlan(from);
+			break;
 		case T_JsonTableParent:
 			retval = _copyJsonTableParent(from);
 			break;

src/backend/nodes/equalfuncs.c

@@ -181,7 +181,9 @@ static bool
 _equalJsonTableParent(const JsonTableParent *a, const JsonTableParent *b)
 {
 	COMPARE_NODE_FIELD(path);
+	COMPARE_STRING_FIELD(name);
 	COMPARE_NODE_FIELD(child);
+	COMPARE_SCALAR_FIELD(outerJoin);
 	COMPARE_SCALAR_FIELD(colMin);
 	COMPARE_SCALAR_FIELD(colMax);
 
@@ -193,6 +195,7 @@ _equalJsonTableSibling(const JsonTableSibling *a, const JsonTableSibling *b)
 {
 	COMPARE_NODE_FIELD(larg);
 	COMPARE_NODE_FIELD(rarg);
+	COMPARE_SCALAR_FIELD(cross);
 
 	return true;
 }

src/backend/nodes/makefuncs.c

@@ -867,6 +867,25 @@ makeJsonBehavior(JsonBehaviorType type, Node *default_expr)
 	return behavior;
 }
 
+/*
+ * makeJsonTableJoinedPlan -
+ *	   creates a joined JsonTablePlan node
+ */
+Node *
+makeJsonTableJoinedPlan(JsonTablePlanJoinType type, Node *plan1, Node *plan2,
+						int location)
+{
+	JsonTablePlan *n = makeNode(JsonTablePlan);
+
+	n->plan_type = JSTP_JOINED;
+	n->join_type = type;
+	n->plan1 = castNode(JsonTablePlan, plan1);
+	n->plan2 = castNode(JsonTablePlan, plan2);
+	n->location = location;
+
+	return (Node *) n;
+}
+
 /*
  * makeJsonEncoding -
  *	  converts JSON encoding name to enum JsonEncoding

src/backend/nodes/outfuncs.c

@@ -1875,7 +1875,9 @@ _outJsonTableParent(StringInfo str, const JsonTableParent *node)
 	WRITE_NODE_TYPE("JSONTABPNODE");
 
 	WRITE_NODE_FIELD(path);
+	WRITE_STRING_FIELD(name);
 	WRITE_NODE_FIELD(child);
+	WRITE_BOOL_FIELD(outerJoin);
 	WRITE_INT_FIELD(colMin);
 	WRITE_INT_FIELD(colMax);
 }
@@ -1887,6 +1889,7 @@ _outJsonTableSibling(StringInfo str, const JsonTableSibling *node)
 
 	WRITE_NODE_FIELD(larg);
 	WRITE_NODE_FIELD(rarg);
+	WRITE_BOOL_FIELD(cross);
 }
 
 /*****************************************************************************

src/backend/nodes/readfuncs.c

@@ -1541,7 +1541,9 @@ _readJsonTableParent(void)
 	READ_LOCALS(JsonTableParent);
 
 	READ_NODE_FIELD(path);
+	READ_STRING_FIELD(name);
 	READ_NODE_FIELD(child);
+	READ_BOOL_FIELD(outerJoin);
 	READ_INT_FIELD(colMin);
 	READ_INT_FIELD(colMax);
 
@@ -1555,6 +1557,7 @@ _readJsonTableSibling(void)
 
 	READ_NODE_FIELD(larg);
 	READ_NODE_FIELD(rarg);
+	READ_BOOL_FIELD(cross);
 
 	READ_DONE();
 }

src/backend/parser/gram.y

@@ -683,6 +683,18 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 					json_table_formatted_column_definition
 					json_table_exists_column_definition
 					json_table_nested_columns
+					json_table_plan_clause_opt
+					json_table_specific_plan
+					json_table_plan
+					json_table_plan_simple
+					json_table_plan_parent_child
+					json_table_plan_outer
+					json_table_plan_inner
+					json_table_plan_sibling
+					json_table_plan_union
+					json_table_plan_cross
+					json_table_plan_primary
+					json_table_default_plan
 
 %type <list>		json_name_and_value_list
 					json_value_expr_list
@@ -698,6 +710,9 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 
 %type <ival>		json_encoding
 					json_encoding_clause_opt
+					json_table_default_plan_choices
+					json_table_default_plan_inner_outer
+					json_table_default_plan_union_cross
 					json_wrapper_clause_opt
 					json_wrapper_behavior
 					json_conditional_or_unconditional_opt
@@ -812,7 +827,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	ORDER ORDINALITY OTHERS OUT_P OUTER_P
 	OVER OVERLAPS OVERLAY OVERRIDING OWNED OWNER
 
-	PARALLEL PARSER PARTIAL PARTITION PASSING PASSWORD PATH PLACING PLANS POLICY
+	PARALLEL PARSER PARTIAL PARTITION PASSING PASSWORD PATH PLACING PLAN PLANS POLICY
 	POSITION PRECEDING PRECISION PRESERVE PREPARE PREPARED PRIMARY
 	PRIOR PRIVILEGES PROCEDURAL PROCEDURE PROCEDURES PROGRAM PUBLICATION
 
@@ -15928,13 +15943,15 @@ json_table:
 			JSON_TABLE '('
 				json_api_common_syntax
 				json_table_columns_clause
+				json_table_plan_clause_opt
 				json_table_error_clause_opt
 			')'
 				{
 					JsonTable *n = makeNode(JsonTable);
 					n->common = (JsonCommon *) $3;
 					n->columns = $4;
-					n->on_error = $5;
+					n->plan = (JsonTablePlan *) $5;
+					n->on_error = $6;
 					n->location = @1;
 					$$ = (Node *) n;
 				}
@@ -16055,12 +16072,15 @@ json_table_formatted_column_definition:
 		;
 
 json_table_nested_columns:
-			NESTED path_opt Sconst json_table_columns_clause
+			NESTED path_opt Sconst
+							json_as_path_name_clause_opt
+							json_table_columns_clause
 				{
 					JsonTableColumn *n = makeNode(JsonTableColumn);
 					n->coltype = JTC_NESTED;
 					n->pathspec = $3;
-					n->columns = $4;
+					n->pathname = $4;
+					n->columns = $5;
 					n->location = @1;
 					$$ = (Node *) n;
 				}
@@ -16071,6 +16091,106 @@ path_opt:
 			| /* EMPTY */							{ }
 		;
 
+json_table_plan_clause_opt:
+			json_table_specific_plan				{ $$ = $1; }
+			| json_table_default_plan				{ $$ = $1; }
+			| /* EMPTY */							{ $$ = NULL; }
+		;
+
+json_table_specific_plan:
+			PLAN '(' json_table_plan ')'			{ $$ = $3; }
+		;
+
+json_table_plan:
+			json_table_plan_simple
+			| json_table_plan_parent_child
+			| json_table_plan_sibling
+		;
+
+json_table_plan_simple:
+			json_table_path_name
+				{
+					JsonTablePlan *n = makeNode(JsonTablePlan);
+					n->plan_type = JSTP_SIMPLE;
+					n->pathname = $1;
+					n->location = @1;
+					$$ = (Node *) n;
+				}
+		;
+
+json_table_plan_parent_child:
+			json_table_plan_outer
+			| json_table_plan_inner
+		;
+
+json_table_plan_outer:
+			json_table_plan_simple OUTER_P json_table_plan_primary
+				{ $$ = makeJsonTableJoinedPlan(JSTPJ_OUTER, $1, $3, @1); }
+		;
+
+json_table_plan_inner:
+			json_table_plan_simple INNER_P json_table_plan_primary
+				{ $$ = makeJsonTableJoinedPlan(JSTPJ_INNER, $1, $3, @1); }
+		;
+
+json_table_plan_sibling:
+			json_table_plan_union
+			| json_table_plan_cross
+		;
+
+json_table_plan_union:
+			json_table_plan_primary UNION json_table_plan_primary
+				{ $$ = makeJsonTableJoinedPlan(JSTPJ_UNION, $1, $3, @1); }
+			| json_table_plan_union UNION json_table_plan_primary
+				{ $$ = makeJsonTableJoinedPlan(JSTPJ_UNION, $1, $3, @1); }
+		;
+
+json_table_plan_cross:
+			json_table_plan_primary CROSS json_table_plan_primary
+				{ $$ = makeJsonTableJoinedPlan(JSTPJ_CROSS, $1, $3, @1); }
+			| json_table_plan_cross CROSS json_table_plan_primary
+				{ $$ = makeJsonTableJoinedPlan(JSTPJ_CROSS, $1, $3, @1); }
+		;
+
+json_table_plan_primary:
+			json_table_plan_simple						{ $$ = $1; }
+			| '(' json_table_plan ')'
+				{
+					castNode(JsonTablePlan, $2)->location = @1;
+					$$ = $2;
+				}
+		;
+
+json_table_default_plan:
+			PLAN DEFAULT '(' json_table_default_plan_choices ')'
+			{
+				JsonTablePlan *n = makeNode(JsonTablePlan);
+				n->plan_type = JSTP_DEFAULT;
+				n->join_type = $4;
+				n->location = @1;
+				$$ = (Node *) n;
+			}
+		;
+
+json_table_default_plan_choices:
+			json_table_default_plan_inner_outer			{ $$ = $1 | JSTPJ_UNION; }
+			| json_table_default_plan_inner_outer ','
+			  json_table_default_plan_union_cross		{ $$ = $1 | $3; }
+			| json_table_default_plan_union_cross		{ $$ = $1 | JSTPJ_OUTER; }
+			| json_table_default_plan_union_cross ','
+			  json_table_default_plan_inner_outer		{ $$ = $1 | $3; }
+		;
+
+json_table_default_plan_inner_outer:
+			INNER_P										{ $$ = JSTPJ_INNER; }
+			| OUTER_P									{ $$ = JSTPJ_OUTER; }
+		;
+
+json_table_default_plan_union_cross:
+			UNION										{ $$ = JSTPJ_UNION; }
+			| CROSS										{ $$ = JSTPJ_CROSS; }
+		;
+
 json_returning_clause_opt:
 			RETURNING Typename
 				{
@@ -16951,6 +17071,7 @@ unreserved_keyword:
 			| PASSING
 			| PASSWORD
 			| PATH
+			| PLAN
 			| PLANS
 			| POLICY
 			| PRECEDING
@@ -17568,6 +17689,7 @@ bare_label_keyword:
 			| PASSWORD
 			| PATH
 			| PLACING
+			| PLAN
 			| PLANS
 			| POLICY
 			| POSITION

src/backend/parser/parse_jsontable.c

@@ -37,13 +37,16 @@ typedef struct JsonTableContext
 	JsonTable  *table;				/* untransformed node */
 	TableFunc  *tablefunc;			/* transformed node	*/
 	List	   *pathNames;			/* list of all path and columns names */
+	int			pathNameId;			/* path name id counter */
 	Oid			contextItemTypid;	/* type oid of context item (json/jsonb) */
 } JsonTableContext;
 
 static JsonTableParent * transformJsonTableColumns(JsonTableContext *cxt,
-													   List *columns,
-													   char *pathSpec,
-													   int location);
+												   JsonTablePlan *plan,
+												   List *columns,
+												   char *pathSpec,
+												   char **pathName,
+												   int location);
 
 static Node *
 makeStringConst(char *str, int location)
@@ -154,62 +157,239 @@ registerAllJsonTableColumns(JsonTableContext *cxt, List *columns)
 		JsonTableColumn *jtc = castNode(JsonTableColumn, lfirst(lc));
 
 		if (jtc->coltype == JTC_NESTED)
+		{
+			if (jtc->pathname)
+				registerJsonTableColumn(cxt, jtc->pathname);
+
 			registerAllJsonTableColumns(cxt, jtc->columns);
+		}
 		else
+		{
 			registerJsonTableColumn(cxt, jtc->name);
+		}
+	}
+}
+
+/* Generate a new unique JSON_TABLE path name. */
+static char *
+generateJsonTablePathName(JsonTableContext *cxt)
+{
+	char		namebuf[32];
+	char	   *name = namebuf;
+
+	do
+	{
+		snprintf(namebuf, sizeof(namebuf), "json_table_path_%d",
+				 ++cxt->pathNameId);
+	} while (isJsonTablePathNameDuplicate(cxt, name));
+
+	name = pstrdup(name);
+	cxt->pathNames = lappend(cxt->pathNames, name);
+
+	return name;
+}
+
+/* Collect sibling path names from plan to the specified list. */
+static void
+collectSiblingPathsInJsonTablePlan(JsonTablePlan *plan, List **paths)
+{
+	if (plan->plan_type == JSTP_SIMPLE)
+		*paths = lappend(*paths, plan->pathname);
+	else if (plan->plan_type == JSTP_JOINED)
+	{
+		if (plan->join_type == JSTPJ_INNER ||
+			plan->join_type == JSTPJ_OUTER)
+		{
+			Assert(plan->plan1->plan_type == JSTP_SIMPLE);
+			*paths = lappend(*paths, plan->plan1->pathname);
+		}
+		else if (plan->join_type == JSTPJ_CROSS ||
+				 plan->join_type == JSTPJ_UNION)
+		{
+			collectSiblingPathsInJsonTablePlan(plan->plan1, paths);
+			collectSiblingPathsInJsonTablePlan(plan->plan2, paths);
+		}
+		else
+			elog(ERROR, "invalid JSON_TABLE join type %d",
+				 plan->join_type);
+	}
+}
+
+/*
+ * Validate child JSON_TABLE plan by checking that:
+ *  - all nested columns have path names specified
+ *  - all nested columns have corresponding node in the sibling plan
+ *  - plan does not contain duplicate or extra nodes
+ */
+static void
+validateJsonTableChildPlan(ParseState *pstate, JsonTablePlan *plan,
+						   List *columns)
+{
+	ListCell   *lc1;
+	List	   *siblings = NIL;
+	int			nchildren = 0;
+
+	if (plan)
+		collectSiblingPathsInJsonTablePlan(plan, &siblings);
+
+	foreach(lc1, columns)
+	{
+		JsonTableColumn *jtc = castNode(JsonTableColumn, lfirst(lc1));
+
+		if (jtc->coltype == JTC_NESTED)
+		{
+			ListCell   *lc2;
+			bool		found = false;
+
+			if (!jtc->pathname)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("nested JSON_TABLE columns must contain an explicit AS pathname specification if an explicit PLAN clause is used"),
+						 parser_errposition(pstate, jtc->location)));
+
+			/* find nested path name in the list of sibling path names */
+			foreach(lc2, siblings)
+			{
+				if ((found = !strcmp(jtc->pathname, lfirst(lc2))))
+					break;
+			}
+
+			if (!found)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("invalid JSON_TABLE plan"),
+						 errdetail("plan node for nested path %s was not found in plan", jtc->pathname),
+						 parser_errposition(pstate, jtc->location)));
+
+			nchildren++;
+		}
+	}
+
+	if (list_length(siblings) > nchildren)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("invalid JSON_TABLE plan"),
+				 errdetail("plan node contains some extra or duplicate sibling nodes"),
+				 parser_errposition(pstate, plan ? plan->location : -1)));
+}
+
+static JsonTableColumn *
+findNestedJsonTableColumn(List *columns, const char *pathname)
+{
+	ListCell   *lc;
+
+	foreach(lc, columns)
+	{
+		JsonTableColumn *jtc = castNode(JsonTableColumn, lfirst(lc));
+
+		if (jtc->coltype == JTC_NESTED &&
+			jtc->pathname &&
+			!strcmp(jtc->pathname, pathname))
+			return jtc;
 	}
+
+	return NULL;
 }
 
 static Node *
-transformNestedJsonTableColumn(JsonTableContext *cxt, JsonTableColumn *jtc)
+transformNestedJsonTableColumn(JsonTableContext *cxt, JsonTableColumn *jtc,
+							   JsonTablePlan *plan)
 {
 	JsonTableParent *node;
+	char	   *pathname = jtc->pathname;
 
-	node = transformJsonTableColumns(cxt, jtc->columns, jtc->pathspec,
-									 jtc->location);
+	node = transformJsonTableColumns(cxt, plan, jtc->columns, jtc->pathspec,
+									 &pathname, jtc->location);
+	node->name = pstrdup(pathname);
 
 	return (Node *) node;
 }
 
 static Node *
-makeJsonTableSiblingJoin(Node *lnode, Node *rnode)
+makeJsonTableSiblingJoin(bool cross, Node *lnode, Node *rnode)
 {
 	JsonTableSibling *join = makeNode(JsonTableSibling);
 
 	join->larg = lnode;
 	join->rarg = rnode;
+	join->cross = cross;
 
 	return (Node *) join;
 }
 
 /*
- * Recursively transform child (nested) JSON_TABLE columns.
+ * Recursively transform child JSON_TABLE plan.
  *
- * Child columns are transformed into a binary tree of union-joined
- * JsonTableSiblings.
+ * Default plan is transformed into a cross/union join of its nested columns.
+ * Simple and outer/inner plans are transformed into a JsonTableParent by
+ * finding and transforming corresponding nested column.
+ * Sibling plans are recursively transformed into a JsonTableSibling.
  */
 static Node *
-transformJsonTableChildColumns(JsonTableContext *cxt, List *columns)
+transformJsonTableChildPlan(JsonTableContext *cxt, JsonTablePlan *plan,
+							List *columns)
 {
-	Node	   *res = NULL;
-	ListCell   *lc;
+	JsonTableColumn *jtc = NULL;
 
-	/* transform all nested columns into union join */
-	foreach(lc, columns)
+	if (!plan || plan->plan_type == JSTP_DEFAULT)
 	{
-		JsonTableColumn *jtc = castNode(JsonTableColumn, lfirst(lc));
-		Node	   *node;
+		/* unspecified or default plan */
+		Node	   *res = NULL;
+		ListCell   *lc;
+		bool		cross = plan && (plan->join_type & JSTPJ_CROSS);
 
-		if (jtc->coltype != JTC_NESTED)
-			continue;
+		/* transform all nested columns into cross/union join */
+		foreach(lc, columns)
+		{
+			JsonTableColumn *jtc = castNode(JsonTableColumn, lfirst(lc));
+			Node *node;
+
+			if (jtc->coltype != JTC_NESTED)
+				continue;
 
-		node = transformNestedJsonTableColumn(cxt, jtc);
+			node = transformNestedJsonTableColumn(cxt, jtc, plan);
 
-		/* join transformed node with previous sibling nodes */
-		res = res ? makeJsonTableSiblingJoin(res, node) : node;
+			/* join transformed node with previous sibling nodes */
+			res = res ? makeJsonTableSiblingJoin(cross, res, node) : node;
+		}
+
+		return res;
 	}
+	else if (plan->plan_type == JSTP_SIMPLE)
+	{
+		jtc = findNestedJsonTableColumn(columns, plan->pathname);
+	}
+	else if (plan->plan_type == JSTP_JOINED)
+	{
+		if (plan->join_type == JSTPJ_INNER ||
+			plan->join_type == JSTPJ_OUTER)
+		{
+			Assert(plan->plan1->plan_type == JSTP_SIMPLE);
+			jtc = findNestedJsonTableColumn(columns, plan->plan1->pathname);
+		}
+		else
+		{
+			Node	   *node1 =
+				transformJsonTableChildPlan(cxt, plan->plan1, columns);
+			Node	   *node2 =
+				transformJsonTableChildPlan(cxt, plan->plan2, columns);
+
+			return makeJsonTableSiblingJoin(plan->join_type == JSTPJ_CROSS,
+											node1, node2);
+		}
+	}
+	else
+		elog(ERROR, "invalid JSON_TABLE plan type %d", plan->plan_type);
+
+	if (!jtc)
+		ereport(ERROR,
+				(errcode(ERRCODE_SYNTAX_ERROR),
+				 errmsg("invalid JSON_TABLE plan"),
+				 errdetail("path name was %s not found in nested columns list",
+						   plan->pathname),
+				 parser_errposition(cxt->pstate, plan->location)));
 
-	return res;
+	return transformNestedJsonTableColumn(cxt, jtc, plan);
 }
 
 /* Check whether type is json/jsonb, array, or record. */
@@ -374,16 +554,80 @@ makeParentJsonTableNode(JsonTableContext *cxt, char *pathSpec, List *columns)
 }
 
 static JsonTableParent *
-transformJsonTableColumns(JsonTableContext *cxt, List *columns, char *pathSpec,
+transformJsonTableColumns(JsonTableContext *cxt, JsonTablePlan *plan,
+						  List *columns, char *pathSpec, char **pathName,
 						  int location)
 {
 	JsonTableParent *node;
+	JsonTablePlan *childPlan;
+	bool		defaultPlan = !plan || plan->plan_type == JSTP_DEFAULT;
+
+	if (!*pathName)
+	{
+		if (cxt->table->plan)
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("invalid JSON_TABLE expression"),
+					 errdetail("JSON_TABLE columns must contain "
+							   "explicit AS pathname specification if "
+							   "explicit PLAN clause is used"),
+					parser_errposition(cxt->pstate, location)));
+
+		*pathName = generateJsonTablePathName(cxt);
+	}
+
+	if (defaultPlan)
+		childPlan = plan;
+	else
+	{
+		/* validate parent and child plans */
+		JsonTablePlan *parentPlan;
+
+		if (plan->plan_type == JSTP_JOINED)
+		{
+			if (plan->join_type != JSTPJ_INNER &&
+				plan->join_type != JSTPJ_OUTER)
+				ereport(ERROR,
+						(errcode(ERRCODE_SYNTAX_ERROR),
+						 errmsg("invalid JSON_TABLE plan"),
+						 errdetail("expected INNER or OUTER JSON_TABLE plan node"),
+						 parser_errposition(cxt->pstate, plan->location)));
+
+			parentPlan = plan->plan1;
+			childPlan = plan->plan2;
+
+			Assert(parentPlan->plan_type != JSTP_JOINED);
+			Assert(parentPlan->pathname);
+		}
+		else
+		{
+			parentPlan = plan;
+			childPlan = NULL;
+		}
+
+		if (strcmp(parentPlan->pathname, *pathName))
+			ereport(ERROR,
+					(errcode(ERRCODE_SYNTAX_ERROR),
+					 errmsg("invalid JSON_TABLE plan"),
+					 errdetail("path name mismatch: expected %s but %s is given",
+							   *pathName, parentPlan->pathname),
+					 parser_errposition(cxt->pstate, plan->location)));
+
+		validateJsonTableChildPlan(cxt->pstate, childPlan, columns);
+	}
 
 	/* transform only non-nested columns */
 	node = makeParentJsonTableNode(cxt, pathSpec, columns);
+	node->name = pstrdup(*pathName);
 
-	/* transform recursively nested columns */
-	node->child = transformJsonTableChildColumns(cxt, columns);
+	if (childPlan || defaultPlan)
+	{
+		/* transform recursively nested columns */
+		node->child = transformJsonTableChildPlan(cxt, childPlan, columns);
+		if (node->child)
+			node->outerJoin = !plan || (plan->join_type & JSTPJ_OUTER);
+		/* else: default plan case, no children found */
+	}
 
 	return node;
 }
@@ -401,7 +645,9 @@ transformJsonTable(ParseState *pstate, JsonTable *jt)
 	JsonTableContext cxt;
 	TableFunc  *tf = makeNode(TableFunc);
 	JsonFuncExpr *jfe = makeNode(JsonFuncExpr);
+	JsonTablePlan *plan = jt->plan;
 	JsonCommon *jscommon;
+	char	   *rootPathName = jt->common->pathname;
 	char	   *rootPath;
 	bool		is_lateral;
 
@@ -409,9 +655,31 @@ transformJsonTable(ParseState *pstate, JsonTable *jt)
 	cxt.table = jt;
 	cxt.tablefunc = tf;
 	cxt.pathNames = NIL;
+	cxt.pathNameId = 0;
+
+	if (rootPathName)
+		registerJsonTableColumn(&cxt, rootPathName);
 
 	registerAllJsonTableColumns(&cxt, jt->columns);
 
+#if 0 /* XXX it' unclear from the standard whether root path name is mandatory or not */
+	if (plan && plan->plan_type != JSTP_DEFAULT && !rootPathName)
+	{
+		/* Assign root path name and create corresponding plan node */
+		JsonTablePlan *rootNode = makeNode(JsonTablePlan);
+		JsonTablePlan *rootPlan = (JsonTablePlan *)
+				makeJsonTableJoinedPlan(JSTPJ_OUTER, (Node *) rootNode,
+										(Node *) plan, jt->location);
+
+		rootPathName = generateJsonTablePathName(&cxt);
+
+		rootNode->plan_type = JSTP_SIMPLE;
+		rootNode->pathname = rootPathName;
+
+		plan = rootPlan;
+	}
+#endif
+
 	jscommon = copyObject(jt->common);
 	jscommon->pathspec = makeStringConst(pstrdup("$"), -1);
 
@@ -447,7 +715,8 @@ transformJsonTable(ParseState *pstate, JsonTable *jt)
 
 	rootPath = castNode(A_Const, jt->common->pathspec)->val.sval.sval;
 
-	tf->plan = (Node *) transformJsonTableColumns(&cxt, jt->columns, rootPath,
+	tf->plan = (Node *) transformJsonTableColumns(&cxt, plan, jt->columns,
+												  rootPath, &rootPathName,
 												  jt->common->location);
 
 	tf->ordinalitycol = -1;		/* undefine ordinality column number */

src/backend/utils/adt/jsonpath_exec.c

@@ -175,6 +175,7 @@ struct JsonTableScanState
 	Datum		current;
 	int			ordinal;
 	bool		currentIsNull;
+	bool		outerJoin;
 	bool		errorOnError;
 	bool		advanceNested;
 	bool		reset;
@@ -188,6 +189,7 @@ struct JsonTableJoinState
 		{
 			JsonTableJoinState *left;
 			JsonTableJoinState *right;
+			bool		cross;
 			bool		advanceRight;
 		}			join;
 		JsonTableScanState scan;
@@ -3166,6 +3168,7 @@ JsonTableInitScanState(JsonTableContext *cxt, JsonTableScanState *scan,
 	int			i;
 
 	scan->parent = parent;
+	scan->outerJoin = node->outerJoin;
 	scan->errorOnError = node->errorOnError;
 	scan->path = DatumGetJsonPathP(node->path->constvalue);
 	scan->args = args;
@@ -3192,6 +3195,7 @@ JsonTableInitPlanState(JsonTableContext *cxt, Node *plan,
 		JsonTableSibling *join = castNode(JsonTableSibling, plan);
 
 		state->is_join = true;
+		state->u.join.cross = join->cross;
 		state->u.join.left = JsonTableInitPlanState(cxt, join->larg, parent);
 		state->u.join.right = JsonTableInitPlanState(cxt, join->rarg, parent);
 	}
@@ -3328,8 +3332,26 @@ JsonTableSetDocument(TableFuncScanState *state, Datum value)
 	JsonTableResetContextItem(&cxt->root, value);
 }
 
+/* Recursively reset scan and its child nodes */
+static void
+JsonTableRescanRecursive(JsonTableJoinState *state)
+{
+	if (state->is_join)
+	{
+		JsonTableRescanRecursive(state->u.join.left);
+		JsonTableRescanRecursive(state->u.join.right);
+		state->u.join.advanceRight = false;
+	}
+	else
+	{
+		JsonTableRescan(&state->u.scan);
+		if (state->u.scan.nested)
+			JsonTableRescanRecursive(state->u.scan.nested);
+	}
+}
+
 /*
- * Fetch next row from a union joined scan.
+ * Fetch next row from a cross/union joined scan.
  *
  * Returns false at the end of a scan, true otherwise.
  */
@@ -3339,17 +3361,48 @@ JsonTableNextJoinRow(JsonTableJoinState *state)
 	if (!state->is_join)
 		return JsonTableNextRow(&state->u.scan);
 
-	if (!state->u.join.advanceRight)
+	if (state->u.join.advanceRight)
 	{
-		/* fetch next outer row */
-		if (JsonTableNextJoinRow(state->u.join.left))
+		/* fetch next inner row */
+		if (JsonTableNextJoinRow(state->u.join.right))
 			return true;
 
-		state->u.join.advanceRight = true;	/* next inner row */
+		/* inner rows are exhausted */
+		if (state->u.join.cross)
+			state->u.join.advanceRight = false;	/* next outer row */
+		else
+			return false;	/* end of scan */
+	}
+
+	while (!state->u.join.advanceRight)
+	{
+		/* fetch next outer row */
+		bool		left = JsonTableNextJoinRow(state->u.join.left);
+
+		if (state->u.join.cross)
+		{
+			if (!left)
+				return false;	/* end of scan */
+
+			JsonTableRescanRecursive(state->u.join.right);
+
+			if (!JsonTableNextJoinRow(state->u.join.right))
+				continue;	/* next outer row */
+
+			state->u.join.advanceRight = true;	/* next inner row */
+		}
+		else if (!left)
+		{
+			if (!JsonTableNextJoinRow(state->u.join.right))
+				return false;	/* end of scan */
+
+			state->u.join.advanceRight = true;	/* next inner row */
+		}
+
+		break;
 	}
 
-	/* fetch next inner row */
-	return JsonTableNextJoinRow(state->u.join.right);
+	return true;
 }
 
 /* Recursively set 'reset' flag of scan and its child nodes */
@@ -3373,16 +3426,13 @@ JsonTableJoinReset(JsonTableJoinState *state)
 }
 
 /*
- * Fetch next row from a simple scan with outer joined nested subscans.
+ * Fetch next row from a simple scan with outer/inner joined nested subscans.
  *
  * Returns false at the end of a scan, true otherwise.
  */
 static bool
 JsonTableNextRow(JsonTableScanState *scan)
 {
-	JsonbValue *jbv;
-	MemoryContext oldcxt;
-
 	/* reset context item if requested */
 	if (scan->reset)
 	{
@@ -3394,34 +3444,42 @@ JsonTableNextRow(JsonTableScanState *scan)
 	if (scan->advanceNested)
 	{
 		/* fetch next nested row */
-		if (JsonTableNextJoinRow(scan->nested))
-			return true;
+		scan->advanceNested = JsonTableNextJoinRow(scan->nested);
 
-		scan->advanceNested = false;
+		if (scan->advanceNested)
+			return true;
 	}
 
-	/* fetch next row */
-	jbv = JsonValueListNext(&scan->found, &scan->iter);
-
-	if (!jbv)
+	for (;;)
 	{
-		scan->current = PointerGetDatum(NULL);
-		scan->currentIsNull = true;
-		return false;	/* end of scan */
-	}
+		/* fetch next row */
+		JsonbValue *jbv = JsonValueListNext(&scan->found, &scan->iter);
+		MemoryContext oldcxt;
 
-	/* set current row item */
-	oldcxt = MemoryContextSwitchTo(scan->mcxt);
-	scan->current = JsonbPGetDatum(JsonbValueToJsonb(jbv));
-	scan->currentIsNull = false;
-	MemoryContextSwitchTo(oldcxt);
+		if (!jbv)
+		{
+			scan->current = PointerGetDatum(NULL);
+			scan->currentIsNull = true;
+			return false;	/* end of scan */
+		}
 
-	scan->ordinal++;
+		/* set current row item */
+		oldcxt = MemoryContextSwitchTo(scan->mcxt);
+		scan->current = JsonbPGetDatum(JsonbValueToJsonb(jbv));
+		scan->currentIsNull = false;
+		MemoryContextSwitchTo(oldcxt);
+
+		scan->ordinal++;
+
+		if (!scan->nested)
+			break;
 
-	if (scan->nested)
-	{
 		JsonTableJoinReset(scan->nested);
+
 		scan->advanceNested = JsonTableNextJoinRow(scan->nested);
+
+		if (scan->advanceNested || scan->outerJoin)
+			break;
 	}
 
 	return true;

src/backend/utils/adt/ruleutils.c

@@ -11169,10 +11169,54 @@ get_json_table_nested_columns(TableFunc *tf, Node *node,
 		 appendStringInfoChar(context->buf, ' ');
 		 appendContextKeyword(context,  "NESTED PATH ", 0, 0, 0);
 		 get_const_expr(n->path, context, -1);
+		 appendStringInfo(context->buf, " AS %s", quote_identifier(n->name));
 		 get_json_table_columns(tf, n, context, showimplicit);
 	}
 }
 
+/*
+ * get_json_table_plan - Parse back a JSON_TABLE plan
+ */
+static void
+get_json_table_plan(TableFunc *tf, Node *node, deparse_context *context,
+					bool parenthesize)
+{
+	if (parenthesize)
+		appendStringInfoChar(context->buf, '(');
+
+	if (IsA(node, JsonTableSibling))
+	{
+		JsonTableSibling *n = (JsonTableSibling *) node;
+
+		get_json_table_plan(tf, n->larg, context,
+							IsA(n->larg, JsonTableSibling) ||
+							castNode(JsonTableParent, n->larg)->child);
+
+		appendStringInfoString(context->buf, n->cross ? " CROSS " : " UNION ");
+
+		get_json_table_plan(tf, n->rarg, context,
+							IsA(n->rarg, JsonTableSibling) ||
+							castNode(JsonTableParent, n->rarg)->child);
+	}
+	else
+	{
+		 JsonTableParent *n = castNode(JsonTableParent, node);
+
+		 appendStringInfoString(context->buf, quote_identifier(n->name));
+
+		 if (n->child)
+		 {
+			appendStringInfoString(context->buf,
+								   n->outerJoin ? " OUTER " : " INNER ");
+			get_json_table_plan(tf, n->child, context,
+								IsA(n->child, JsonTableSibling));
+		 }
+	}
+
+	if (parenthesize)
+		appendStringInfoChar(context->buf, ')');
+}
+
 /*
  * get_json_table_columns - Parse back JSON_TABLE columns
  */
@@ -11301,6 +11345,8 @@ get_json_table(TableFunc *tf, deparse_context *context, bool showimplicit)
 
 	get_const_expr(root->path, context, -1);
 
+	appendStringInfo(buf, " AS %s", quote_identifier(root->name));
+
 	if (jexpr->passing_values)
 	{
 		ListCell   *lc1, *lc2;
@@ -11333,6 +11379,10 @@ get_json_table(TableFunc *tf, deparse_context *context, bool showimplicit)
 
 	get_json_table_columns(tf, root, context, showimplicit);
 
+	appendStringInfoChar(buf, ' ');
+	appendContextKeyword(context, "PLAN ", 0, 0, 0);
+	get_json_table_plan(tf, (Node *) root, context, true);
+
 	if (jexpr->on_error->btype != JSON_BEHAVIOR_EMPTY)
 		get_json_behavior(jexpr->on_error, context, "ERROR");
 

src/include/nodes/makefuncs.h

@@ -110,6 +110,8 @@ extern JsonFormat *makeJsonFormat(JsonFormatType type, JsonEncoding encoding,
 								  int location);
 extern JsonValueExpr *makeJsonValueExpr(Expr *expr, JsonFormat *format);
 extern JsonBehavior *makeJsonBehavior(JsonBehaviorType type, Node *expr);
+extern Node *makeJsonTableJoinedPlan(JsonTablePlanJoinType type,
+									 Node *plan1, Node *plan2, int location);
 extern Node *makeJsonKeyValue(Node *key, Node *value);
 extern Node *makeJsonIsPredicate(Node *expr, JsonFormat *format,
 								 JsonValueType vtype, bool unique_keys,

src/include/nodes/nodes.h

@@ -518,6 +518,7 @@ typedef enum NodeTag
 	T_JsonIsPredicate,
 	T_JsonTable,
 	T_JsonTableColumn,
+	T_JsonTablePlan,
 	T_JsonCommon,
 	T_JsonArgument,
 	T_JsonKeyValue,

src/include/nodes/parsenodes.h

@@ -1688,6 +1688,7 @@ typedef struct JsonTableColumn
 	char	   *name;				/* column name */
 	TypeName   *typeName;			/* column type name */
 	JsonPathSpec pathspec;			/* path specification, if any */
+	char	   *pathname;			/* path name, if any */
 	JsonFormat *format;				/* JSON format clause, if specified */
 	JsonWrapper	wrapper;			/* WRAPPER behavior for formatted columns */
 	bool		omit_quotes;		/* omit or keep quotes on scalar strings? */
@@ -1697,6 +1698,46 @@ typedef struct JsonTableColumn
 	int			location;			/* token location, or -1 if unknown */
 } JsonTableColumn;
 
+/*
+ * JsonTablePlanType -
+ *		flags for JSON_TABLE plan node types representation
+ */
+typedef enum JsonTablePlanType
+{
+	JSTP_DEFAULT,
+	JSTP_SIMPLE,
+	JSTP_JOINED,
+} JsonTablePlanType;
+
+/*
+ * JsonTablePlanJoinType -
+ *		flags for JSON_TABLE join types representation
+ */
+typedef enum JsonTablePlanJoinType
+{
+	JSTPJ_INNER = 0x01,
+	JSTPJ_OUTER = 0x02,
+	JSTPJ_CROSS = 0x04,
+	JSTPJ_UNION = 0x08,
+} JsonTablePlanJoinType;
+
+typedef struct JsonTablePlan JsonTablePlan;
+
+/*
+ * JsonTablePlan -
+ *		untransformed representation of JSON_TABLE plan node
+ */
+struct JsonTablePlan
+{
+	NodeTag		type;
+	JsonTablePlanType plan_type;		/* plan type */
+	JsonTablePlanJoinType join_type;	/* join type (for joined plan only) */
+	JsonTablePlan *plan1;				/* first joined plan */
+	JsonTablePlan *plan2;				/* second joined plan */
+	char	   *pathname;				/* path name (for simple plan only) */
+	int			location;				/* token location, or -1 if unknown */
+};
+
 /*
  * JsonTable -
  *		untransformed representation of JSON_TABLE
@@ -1706,6 +1747,7 @@ typedef struct JsonTable
 	NodeTag		type;
 	JsonCommon *common;					/* common JSON path syntax fields */
 	List	   *columns;				/* list of JsonTableColumn */
+	JsonTablePlan *plan;				/* join plan, if specified */
 	JsonBehavior *on_error;				/* ON ERROR behavior, if specified */
 	Alias	   *alias;					/* table alias in FROM clause */
 	bool		lateral;				/* does it have LATERAL prefix? */

src/include/nodes/primnodes.h

@@ -1473,7 +1473,9 @@ typedef struct JsonTableParent
 {
 	NodeTag		type;
 	Const	   *path;		/* jsonpath constant */
+	char	   *name;		/* path name */
 	Node	   *child;		/* nested columns, if any */
+	bool		outerJoin;	/* outer or inner join for nested columns? */
 	int			colMin;		/* min column index in the resulting column list */
 	int			colMax;		/* max column index in the resulting column list */
 	bool		errorOnError; /* ERROR/EMPTY ON ERROR behavior */
@@ -1488,6 +1490,7 @@ typedef struct JsonTableSibling
 	NodeTag		type;
 	Node	   *larg;		/* left join node */
 	Node	   *rarg;		/* right join node */
+	bool		cross;		/* cross or union join? */
 } JsonTableSibling;
 
 /* ----------------

src/include/parser/kwlist.h

@@ -336,6 +336,7 @@ PG_KEYWORD("passing", PASSING, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("password", PASSWORD, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("path", PATH, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("placing", PLACING, RESERVED_KEYWORD, BARE_LABEL)
+PG_KEYWORD("plan", PLAN, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("plans", PLANS, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("policy", POLICY, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("position", POSITION, COL_NAME_KEYWORD, BARE_LABEL)

src/test/regress/expected/jsonb_sqljson.out

@@ -1140,18 +1140,18 @@ SELECT * FROM
 			ia int[] PATH '$',
 			ta text[] PATH '$',
 			jba jsonb[] PATH '$',
-			NESTED PATH '$[1]' COLUMNS (
+			NESTED PATH '$[1]' AS p1 COLUMNS (
 				a1 int,
-				NESTED PATH '$[*]' COLUMNS (
+				NESTED PATH '$[*]' AS "p1 1" COLUMNS (
 					a11 text
 				),
 				b1 text
 			),
-			NESTED PATH '$[2]' COLUMNS (
-				NESTED PATH '$[*]' COLUMNS (
+			NESTED PATH '$[2]' AS p2 COLUMNS (
+				NESTED PATH '$[*]' AS "p2:1" COLUMNS (
 					a21 text
 				),
-				NESTED PATH '$[*]' COLUMNS (
+				NESTED PATH '$[*]' AS p22 COLUMNS (
 					a22 text
 				)
 			)
@@ -1191,7 +1191,7 @@ CREATE OR REPLACE VIEW public.jsonb_table_view AS
     "json_table".a21,
     "json_table".a22
    FROM JSON_TABLE(
-            'null'::jsonb, '$[*]'
+            'null'::jsonb, '$[*]' AS json_table_path_1
             PASSING
                 1 + 2 AS a,
                 '"foo"'::json AS "b c"
@@ -1222,34 +1222,35 @@ CREATE OR REPLACE VIEW public.jsonb_table_view AS
                 ia integer[] PATH '$',
                 ta text[] PATH '$',
                 jba jsonb[] PATH '$',
-                NESTED PATH '$[1]'
+                NESTED PATH '$[1]' AS p1
                 COLUMNS (
                     a1 integer PATH '$."a1"',
                     b1 text PATH '$."b1"',
-                    NESTED PATH '$[*]'
+                    NESTED PATH '$[*]' AS "p1 1"
                     COLUMNS (
                         a11 text PATH '$."a11"'
                     )
                 ),
-                NESTED PATH '$[2]'
+                NESTED PATH '$[2]' AS p2
                 COLUMNS (
-                    NESTED PATH '$[*]'
+                    NESTED PATH '$[*]' AS "p2:1"
                     COLUMNS (
                         a21 text PATH '$."a21"'
                     ),
-                    NESTED PATH '$[*]'
+                    NESTED PATH '$[*]' AS p22
                     COLUMNS (
                         a22 text PATH '$."a22"'
                     )
                 )
             )
+            PLAN (json_table_path_1 OUTER ((p1 OUTER "p1 1") UNION (p2 OUTER ("p2:1" UNION p22))))
         )
 EXPLAIN (COSTS OFF, VERBOSE) SELECT * FROM jsonb_table_view;
-                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                QUERY PLAN                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         QUERY PLAN                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          
+-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Table Function Scan on "json_table"
    Output: "json_table".id, "json_table".id2, "json_table"."int", "json_table".text, "json_table"."char(4)", "json_table".bool, "json_table"."numeric", "json_table".domain, "json_table".js, "json_table".jb, "json_table".jst, "json_table".jsc, "json_table".jsv, "json_table".jsb, "json_table".jsbq, "json_table".aaa, "json_table".aaa1, "json_table".exists1, "json_table".exists2, "json_table".exists3, "json_table".js2, "json_table".jsb2w, "json_table".jsb2q, "json_table".ia, "json_table".ta, "json_table".jba, "json_table".a1, "json_table".b1, "json_table".a11, "json_table".a21, "json_table".a22
-   Table Function Call: JSON_TABLE('null'::jsonb, '$[*]' PASSING 3 AS a, '"foo"'::jsonb AS "b c" COLUMNS (id FOR ORDINALITY, id2 FOR ORDINALITY, "int" integer PATH '$', text text PATH '$', "char(4)" character(4) PATH '$', bool boolean PATH '$', "numeric" numeric PATH '$', domain jsonb_test_domain PATH '$', js json PATH '$', jb jsonb PATH '$', jst text FORMAT JSON PATH '$', jsc character(4) FORMAT JSON PATH '$', jsv character varying(4) FORMAT JSON PATH '$', jsb jsonb PATH '$', jsbq jsonb PATH '$' OMIT QUOTES, aaa integer PATH '$."aaa"', aaa1 integer PATH '$."aaa"', exists1 boolean EXISTS PATH '$."aaa"', exists2 integer EXISTS PATH '$."aaa"' TRUE ON ERROR, exists3 text EXISTS PATH 'strict $."aaa"' UNKNOWN ON ERROR, js2 json PATH '$', jsb2w jsonb PATH '$' WITH UNCONDITIONAL WRAPPER, jsb2q jsonb PATH '$' OMIT QUOTES, ia integer[] PATH '$', ta text[] PATH '$', jba jsonb[] PATH '$', NESTED PATH '$[1]' COLUMNS (a1 integer PATH '$."a1"', b1 text PATH '$."b1"', NESTED PATH '$[*]' COLUMNS (a11 text PATH '$."a11"')), NESTED PATH '$[2]' COLUMNS ( NESTED PATH '$[*]' COLUMNS (a21 text PATH '$."a21"'), NESTED PATH '$[*]' COLUMNS (a22 text PATH '$."a22"'))))
+   Table Function Call: JSON_TABLE('null'::jsonb, '$[*]' AS json_table_path_1 PASSING 3 AS a, '"foo"'::jsonb AS "b c" COLUMNS (id FOR ORDINALITY, id2 FOR ORDINALITY, "int" integer PATH '$', text text PATH '$', "char(4)" character(4) PATH '$', bool boolean PATH '$', "numeric" numeric PATH '$', domain jsonb_test_domain PATH '$', js json PATH '$', jb jsonb PATH '$', jst text FORMAT JSON PATH '$', jsc character(4) FORMAT JSON PATH '$', jsv character varying(4) FORMAT JSON PATH '$', jsb jsonb PATH '$', jsbq jsonb PATH '$' OMIT QUOTES, aaa integer PATH '$."aaa"', aaa1 integer PATH '$."aaa"', exists1 boolean EXISTS PATH '$."aaa"', exists2 integer EXISTS PATH '$."aaa"' TRUE ON ERROR, exists3 text EXISTS PATH 'strict $."aaa"' UNKNOWN ON ERROR, js2 json PATH '$', jsb2w jsonb PATH '$' WITH UNCONDITIONAL WRAPPER, jsb2q jsonb PATH '$' OMIT QUOTES, ia integer[] PATH '$', ta text[] PATH '$', jba jsonb[] PATH '$', NESTED PATH '$[1]' AS p1 COLUMNS (a1 integer PATH '$."a1"', b1 text PATH '$."b1"', NESTED PATH '$[*]' AS "p1 1" COLUMNS (a11 text PATH '$."a11"')), NESTED PATH '$[2]' AS p2 COLUMNS ( NESTED PATH '$[*]' AS "p2:1" COLUMNS (a21 text PATH '$."a21"'), NESTED PATH '$[*]' AS p22 COLUMNS (a22 text PATH '$."a22"'))) PLAN (json_table_path_1 OUTER ((p1 OUTER "p1 1") UNION (p2 OUTER ("p2:1" UNION p22)))))
 (3 rows)
 
 DROP VIEW jsonb_table_view;
@@ -1341,13 +1342,49 @@ ERROR:  cannot cast type boolean to jsonb
 LINE 1: ...ELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a jsonb EX...
                                                              ^
 -- JSON_TABLE: nested paths and plans
+-- Should fail (JSON_TABLE columns must contain explicit AS path
+-- specifications if explicit PLAN clause is used)
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$' -- AS <path name> required here
+	COLUMNS (
+		foo int PATH '$'
+	)
+	PLAN DEFAULT (UNION)
+) jt;
+ERROR:  invalid JSON_TABLE expression
+LINE 2:  jsonb '[]', '$' -- AS <path name> required here
+         ^
+DETAIL:  JSON_TABLE columns must contain explicit AS pathname specification if explicit PLAN clause is used
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$' AS path1
+	COLUMNS (
+		NESTED PATH '$' COLUMNS ( -- AS <path name> required here
+			foo int PATH '$'
+		)
+	)
+	PLAN DEFAULT (UNION)
+) jt;
+ERROR:  invalid JSON_TABLE expression
+LINE 4:   NESTED PATH '$' COLUMNS ( -- AS <path name> required here
+          ^
+DETAIL:  JSON_TABLE columns must contain explicit AS pathname specification if explicit PLAN clause is used
 -- Should fail (column names must be distinct)
 SELECT * FROM JSON_TABLE(
-	jsonb '[]', '$'
+	jsonb '[]', '$' AS a
+	COLUMNS (
+		a int
+	)
+) jt;
+ERROR:  duplicate JSON_TABLE column name: a
+HINT:  JSON_TABLE column names must be distinct from one another
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$' AS a
 	COLUMNS (
-		a int,
-		b text,
-		a jsonb
+		b int,
+		NESTED PATH '$' AS a
+		COLUMNS (
+			c int
+		)
 	)
 ) jt;
 ERROR:  duplicate JSON_TABLE column name: a
@@ -1356,10 +1393,9 @@ SELECT * FROM JSON_TABLE(
 	jsonb '[]', '$'
 	COLUMNS (
 		b int,
-		NESTED PATH '$'
+		NESTED PATH '$' AS b
 		COLUMNS (
-			c int,
-			b text
+			c int
 		)
 	)
 ) jt;
@@ -1368,22 +1404,209 @@ HINT:  JSON_TABLE column names must be distinct from one another
 SELECT * FROM JSON_TABLE(
 	jsonb '[]', '$'
 	COLUMNS (
-		NESTED PATH '$'
+		NESTED PATH '$' AS a
 		COLUMNS (
 			b int
 		),
 		NESTED PATH '$'
 		COLUMNS (
-			NESTED PATH '$'
+			NESTED PATH '$' AS a
 			COLUMNS (
-				c int,
-				b text
+				c int
 			)
 		)
 	)
 ) jt;
-ERROR:  duplicate JSON_TABLE column name: b
+ERROR:  duplicate JSON_TABLE column name: a
 HINT:  JSON_TABLE column names must be distinct from one another
+-- JSON_TABLE: plan validation
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p1)
+) jt;
+ERROR:  invalid JSON_TABLE plan
+LINE 12:  PLAN (p1)
+                ^
+DETAIL:  path name mismatch: expected p0 but p1 is given
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0)
+) jt;
+ERROR:  invalid JSON_TABLE plan
+LINE 4:   NESTED PATH '$' AS p1 COLUMNS (
+          ^
+DETAIL:  plan node for nested path p1 was not found in plan
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER p3)
+) jt;
+ERROR:  invalid JSON_TABLE plan
+LINE 4:   NESTED PATH '$' AS p1 COLUMNS (
+          ^
+DETAIL:  plan node for nested path p1 was not found in plan
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 UNION p1 UNION p11)
+) jt;
+ERROR:  invalid JSON_TABLE plan
+LINE 12:  PLAN (p0 UNION p1 UNION p11)
+                ^
+DETAIL:  expected INNER or OUTER JSON_TABLE plan node
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER (p1 CROSS p13))
+) jt;
+ERROR:  invalid JSON_TABLE plan
+LINE 8:   NESTED PATH '$' AS p2 COLUMNS (
+          ^
+DETAIL:  plan node for nested path p2 was not found in plan
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER (p1 CROSS p2))
+) jt;
+ERROR:  invalid JSON_TABLE plan
+LINE 5:    NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+           ^
+DETAIL:  plan node for nested path p11 was not found in plan
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER ((p1 UNION p11) CROSS p2))
+) jt;
+ERROR:  invalid JSON_TABLE plan
+LINE 12:  PLAN (p0 OUTER ((p1 UNION p11) CROSS p2))
+                         ^
+DETAIL:  plan node contains some extra or duplicate sibling nodes
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER ((p1 INNER p11) CROSS p2))
+) jt;
+ERROR:  invalid JSON_TABLE plan
+LINE 6:    NESTED PATH '$' AS p12 COLUMNS ( bar int )
+           ^
+DETAIL:  plan node for nested path p12 was not found in plan
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER ((p1 INNER (p12 CROSS p11)) CROSS p2))
+) jt;
+ERROR:  invalid JSON_TABLE plan
+LINE 9:    NESTED PATH '$' AS p21 COLUMNS ( baz int )
+           ^
+DETAIL:  plan node for nested path p21 was not found in plan
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', 'strict $[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER ((p1 INNER (p12 CROSS p11)) CROSS (p2 INNER p21)))
+) jt;
+ bar | foo | baz 
+-----+-----+-----
+(0 rows)
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', 'strict $[*]' -- without root path name
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN ((p1 INNER (p12 CROSS p11)) CROSS (p2 INNER p21))
+) jt;
+ERROR:  invalid JSON_TABLE expression
+LINE 2:  jsonb 'null', 'strict $[*]' -- without root path name
+         ^
+DETAIL:  JSON_TABLE columns must contain explicit AS pathname specification if explicit PLAN clause is used
 -- JSON_TABLE: plan execution
 CREATE TEMP TABLE jsonb_table_test (js jsonb);
 INSERT INTO jsonb_table_test
@@ -1401,12 +1624,12 @@ select
 from
 	jsonb_table_test jtt,
 	json_table (
-		jtt.js,'strict $[*]'
+		jtt.js,'strict $[*]' as p
 		columns (
 			n for ordinality,
 			a int path 'lax $.a' default -1 on empty,
-			nested path 'strict $.b[*]' columns ( b int path '$' ),
-			nested path 'strict $.c[*]' columns ( c int path '$' )
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
 		)
 	) jt;
  n | a  | b | c  
@@ -1424,6 +1647,325 @@ from
  4 | -1 | 2 |   
 (11 rows)
 
+-- default plan (outer, union)
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan default (outer, union)
+	) jt;
+ n | a  | b | c  
+---+----+---+----
+ 1 |  1 |   |   
+ 2 |  2 | 1 |   
+ 2 |  2 | 2 |   
+ 2 |  2 | 3 |   
+ 2 |  2 |   | 10
+ 2 |  2 |   |   
+ 2 |  2 |   | 20
+ 3 |  3 | 1 |   
+ 3 |  3 | 2 |   
+ 4 | -1 | 1 |   
+ 4 | -1 | 2 |   
+(11 rows)
+
+-- specific plan (p outer (pb union pc))
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan (p outer (pb union pc))
+	) jt;
+ n | a  | b | c  
+---+----+---+----
+ 1 |  1 |   |   
+ 2 |  2 | 1 |   
+ 2 |  2 | 2 |   
+ 2 |  2 | 3 |   
+ 2 |  2 |   | 10
+ 2 |  2 |   |   
+ 2 |  2 |   | 20
+ 3 |  3 | 1 |   
+ 3 |  3 | 2 |   
+ 4 | -1 | 1 |   
+ 4 | -1 | 2 |   
+(11 rows)
+
+-- specific plan (p outer (pc union pb))
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan (p outer (pc union pb))
+	) jt;
+ n | a  | c  | b 
+---+----+----+---
+ 1 |  1 |    |  
+ 2 |  2 | 10 |  
+ 2 |  2 |    |  
+ 2 |  2 | 20 |  
+ 2 |  2 |    | 1
+ 2 |  2 |    | 2
+ 2 |  2 |    | 3
+ 3 |  3 |    | 1
+ 3 |  3 |    | 2
+ 4 | -1 |    | 1
+ 4 | -1 |    | 2
+(11 rows)
+
+-- default plan (inner, union)
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan default (inner)
+	) jt;
+ n | a  | b | c  
+---+----+---+----
+ 2 |  2 | 1 |   
+ 2 |  2 | 2 |   
+ 2 |  2 | 3 |   
+ 2 |  2 |   | 10
+ 2 |  2 |   |   
+ 2 |  2 |   | 20
+ 3 |  3 | 1 |   
+ 3 |  3 | 2 |   
+ 4 | -1 | 1 |   
+ 4 | -1 | 2 |   
+(10 rows)
+
+-- specific plan (p inner (pb union pc))
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan (p inner (pb union pc))
+	) jt;
+ n | a  | b | c  
+---+----+---+----
+ 2 |  2 | 1 |   
+ 2 |  2 | 2 |   
+ 2 |  2 | 3 |   
+ 2 |  2 |   | 10
+ 2 |  2 |   |   
+ 2 |  2 |   | 20
+ 3 |  3 | 1 |   
+ 3 |  3 | 2 |   
+ 4 | -1 | 1 |   
+ 4 | -1 | 2 |   
+(10 rows)
+
+-- default plan (inner, cross)
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan default (cross, inner)
+	) jt;
+ n | a | b | c  
+---+---+---+----
+ 2 | 2 | 1 | 10
+ 2 | 2 | 1 |   
+ 2 | 2 | 1 | 20
+ 2 | 2 | 2 | 10
+ 2 | 2 | 2 |   
+ 2 | 2 | 2 | 20
+ 2 | 2 | 3 | 10
+ 2 | 2 | 3 |   
+ 2 | 2 | 3 | 20
+(9 rows)
+
+-- specific plan (p inner (pb cross pc))
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan (p inner (pb cross pc))
+	) jt;
+ n | a | b | c  
+---+---+---+----
+ 2 | 2 | 1 | 10
+ 2 | 2 | 1 |   
+ 2 | 2 | 1 | 20
+ 2 | 2 | 2 | 10
+ 2 | 2 | 2 |   
+ 2 | 2 | 2 | 20
+ 2 | 2 | 3 | 10
+ 2 | 2 | 3 |   
+ 2 | 2 | 3 | 20
+(9 rows)
+
+-- default plan (outer, cross)
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan default (outer, cross)
+	) jt;
+ n | a  | b | c  
+---+----+---+----
+ 1 |  1 |   |   
+ 2 |  2 | 1 | 10
+ 2 |  2 | 1 |   
+ 2 |  2 | 1 | 20
+ 2 |  2 | 2 | 10
+ 2 |  2 | 2 |   
+ 2 |  2 | 2 | 20
+ 2 |  2 | 3 | 10
+ 2 |  2 | 3 |   
+ 2 |  2 | 3 | 20
+ 3 |  3 |   |   
+ 4 | -1 |   |   
+(12 rows)
+
+-- specific plan (p outer (pb cross pc))
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan (p outer (pb cross pc))
+	) jt;
+ n | a  | b | c  
+---+----+---+----
+ 1 |  1 |   |   
+ 2 |  2 | 1 | 10
+ 2 |  2 | 1 |   
+ 2 |  2 | 1 | 20
+ 2 |  2 | 2 | 10
+ 2 |  2 | 2 |   
+ 2 |  2 | 2 | 20
+ 2 |  2 | 3 | 10
+ 2 |  2 | 3 |   
+ 2 |  2 | 3 | 20
+ 3 |  3 |   |   
+ 4 | -1 |   |   
+(12 rows)
+
+select
+	jt.*, b1 + 100 as b
+from
+	json_table (jsonb
+		'[
+			{"a":  1,  "b": [[1, 10], [2], [3, 30, 300]], "c": [1, null, 2]},
+			{"a":  2,  "b": [10, 20], "c": [1, null, 2]},
+			{"x": "3", "b": [11, 22, 33, 44]}
+		 ]',
+		'$[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on error,
+			nested path 'strict $.b[*]' as pb columns (
+				b text format json path '$',
+				nested path 'strict $[*]' as pb1 columns (
+					b1 int path '$'
+				)
+			),
+			nested path 'strict $.c[*]' as pc columns (
+				c text format json path '$',
+				nested path 'strict $[*]' as pc1 columns (
+					c1 int path '$'
+				)
+			)
+		)
+		--plan default(outer, cross)
+		plan(p outer ((pb inner pb1) cross (pc outer pc1)))
+	) jt;
+ n | a |      b       | b1  |  c   | c1 |  b  
+---+---+--------------+-----+------+----+-----
+ 1 | 1 | [1, 10]      |   1 | 1    |    | 101
+ 1 | 1 | [1, 10]      |   1 | null |    | 101
+ 1 | 1 | [1, 10]      |   1 | 2    |    | 101
+ 1 | 1 | [1, 10]      |  10 | 1    |    | 110
+ 1 | 1 | [1, 10]      |  10 | null |    | 110
+ 1 | 1 | [1, 10]      |  10 | 2    |    | 110
+ 1 | 1 | [2]          |   2 | 1    |    | 102
+ 1 | 1 | [2]          |   2 | null |    | 102
+ 1 | 1 | [2]          |   2 | 2    |    | 102
+ 1 | 1 | [3, 30, 300] |   3 | 1    |    | 103
+ 1 | 1 | [3, 30, 300] |   3 | null |    | 103
+ 1 | 1 | [3, 30, 300] |   3 | 2    |    | 103
+ 1 | 1 | [3, 30, 300] |  30 | 1    |    | 130
+ 1 | 1 | [3, 30, 300] |  30 | null |    | 130
+ 1 | 1 | [3, 30, 300] |  30 | 2    |    | 130
+ 1 | 1 | [3, 30, 300] | 300 | 1    |    | 400
+ 1 | 1 | [3, 30, 300] | 300 | null |    | 400
+ 1 | 1 | [3, 30, 300] | 300 | 2    |    | 400
+ 2 | 2 |              |     |      |    |    
+ 3 |   |              |     |      |    |    
+(20 rows)
+
 -- Should succeed (JSON arguments are passed to root and nested paths)
 SELECT *
 FROM

src/test/regress/sql/jsonb_sqljson.sql

@@ -418,18 +418,18 @@ SELECT * FROM
 			ta text[] PATH '$',
 			jba jsonb[] PATH '$',
 
-			NESTED PATH '$[1]' COLUMNS (
+			NESTED PATH '$[1]' AS p1 COLUMNS (
 				a1 int,
-				NESTED PATH '$[*]' COLUMNS (
+				NESTED PATH '$[*]' AS "p1 1" COLUMNS (
 					a11 text
 				),
 				b1 text
 			),
-			NESTED PATH '$[2]' COLUMNS (
-				NESTED PATH '$[*]' COLUMNS (
+			NESTED PATH '$[2]' AS p2 COLUMNS (
+				NESTED PATH '$[*]' AS "p2:1" COLUMNS (
 					a21 text
 				),
-				NESTED PATH '$[*]' COLUMNS (
+				NESTED PATH '$[*]' AS p22 COLUMNS (
 					a22 text
 				)
 			)
@@ -482,13 +482,42 @@ SELECT * FROM JSON_TABLE(jsonb '"a"', '$' COLUMNS (a jsonb EXISTS PATH '$.a'));
 
 -- JSON_TABLE: nested paths and plans
 
+-- Should fail (JSON_TABLE columns must contain explicit AS path
+-- specifications if explicit PLAN clause is used)
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$' -- AS <path name> required here
+	COLUMNS (
+		foo int PATH '$'
+	)
+	PLAN DEFAULT (UNION)
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$' AS path1
+	COLUMNS (
+		NESTED PATH '$' COLUMNS ( -- AS <path name> required here
+			foo int PATH '$'
+		)
+	)
+	PLAN DEFAULT (UNION)
+) jt;
+
 -- Should fail (column names must be distinct)
 SELECT * FROM JSON_TABLE(
-	jsonb '[]', '$'
+	jsonb '[]', '$' AS a
 	COLUMNS (
-		a int,
-		b text,
-		a jsonb
+		a int
+	)
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$' AS a
+	COLUMNS (
+		b int,
+		NESTED PATH '$' AS a
+		COLUMNS (
+			c int
+		)
 	)
 ) jt;
 
@@ -496,10 +525,9 @@ SELECT * FROM JSON_TABLE(
 	jsonb '[]', '$'
 	COLUMNS (
 		b int,
-		NESTED PATH '$'
+		NESTED PATH '$' AS b
 		COLUMNS (
-			c int,
-			b text
+			c int
 		)
 	)
 ) jt;
@@ -507,21 +535,176 @@ SELECT * FROM JSON_TABLE(
 SELECT * FROM JSON_TABLE(
 	jsonb '[]', '$'
 	COLUMNS (
-		NESTED PATH '$'
+		NESTED PATH '$' AS a
 		COLUMNS (
 			b int
 		),
 		NESTED PATH '$'
 		COLUMNS (
-			NESTED PATH '$'
+			NESTED PATH '$' AS a
 			COLUMNS (
-				c int,
-				b text
+				c int
 			)
 		)
 	)
 ) jt;
 
+-- JSON_TABLE: plan validation
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p1)
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0)
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER p3)
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 UNION p1 UNION p11)
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER (p1 CROSS p13))
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER (p1 CROSS p2))
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER ((p1 UNION p11) CROSS p2))
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER ((p1 INNER p11) CROSS p2))
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', '$[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER ((p1 INNER (p12 CROSS p11)) CROSS p2))
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', 'strict $[*]' AS p0
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN (p0 OUTER ((p1 INNER (p12 CROSS p11)) CROSS (p2 INNER p21)))
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb 'null', 'strict $[*]' -- without root path name
+	COLUMNS (
+		NESTED PATH '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int ),
+			NESTED PATH '$' AS p12 COLUMNS ( bar int )
+		),
+		NESTED PATH '$' AS p2 COLUMNS (
+			NESTED PATH '$' AS p21 COLUMNS ( baz int )
+		)
+	)
+	PLAN ((p1 INNER (p12 CROSS p11)) CROSS (p2 INNER p21))
+) jt;
+
 -- JSON_TABLE: plan execution
 
 CREATE TEMP TABLE jsonb_table_test (js jsonb);
@@ -542,13 +725,188 @@ select
 from
 	jsonb_table_test jtt,
 	json_table (
-		jtt.js,'strict $[*]'
+		jtt.js,'strict $[*]' as p
 		columns (
 			n for ordinality,
 			a int path 'lax $.a' default -1 on empty,
-			nested path 'strict $.b[*]' columns ( b int path '$' ),
-			nested path 'strict $.c[*]' columns ( c int path '$' )
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+	) jt;
+
+-- default plan (outer, union)
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan default (outer, union)
+	) jt;
+
+-- specific plan (p outer (pb union pc))
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan (p outer (pb union pc))
+	) jt;
+
+-- specific plan (p outer (pc union pb))
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan (p outer (pc union pb))
+	) jt;
+
+-- default plan (inner, union)
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan default (inner)
+	) jt;
+
+-- specific plan (p inner (pb union pc))
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan (p inner (pb union pc))
+	) jt;
+
+-- default plan (inner, cross)
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan default (cross, inner)
+	) jt;
+
+-- specific plan (p inner (pb cross pc))
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan (p inner (pb cross pc))
+	) jt;
+
+-- default plan (outer, cross)
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan default (outer, cross)
+	) jt;
+
+-- specific plan (p outer (pb cross pc))
+select
+	jt.*
+from
+	jsonb_table_test jtt,
+	json_table (
+		jtt.js,'strict $[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on empty,
+			nested path 'strict $.b[*]' as pb columns ( b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns ( c int path '$' )
+		)
+		plan (p outer (pb cross pc))
+	) jt;
+
+
+select
+	jt.*, b1 + 100 as b
+from
+	json_table (jsonb
+		'[
+			{"a":  1,  "b": [[1, 10], [2], [3, 30, 300]], "c": [1, null, 2]},
+			{"a":  2,  "b": [10, 20], "c": [1, null, 2]},
+			{"x": "3", "b": [11, 22, 33, 44]}
+		 ]',
+		'$[*]' as p
+		columns (
+			n for ordinality,
+			a int path 'lax $.a' default -1 on error,
+			nested path 'strict $.b[*]' as pb columns (
+				b text format json path '$',
+				nested path 'strict $[*]' as pb1 columns (
+					b1 int path '$'
+				)
+			),
+			nested path 'strict $.c[*]' as pc columns (
+				c text format json path '$',
+				nested path 'strict $[*]' as pc1 columns (
+					c1 int path '$'
+				)
+			)
 		)
+		--plan default(outer, cross)
+		plan(p outer ((pb inner pb1) cross (pc outer pc1)))
 	) jt;
 
 -- Should succeed (JSON arguments are passed to root and nested paths)

src/tools/pgindent/typedefs.list

@@ -1244,6 +1244,9 @@ JsonTableColumnType
 JsonTableContext
 JsonTableJoinState
 JsonTableParent
+JsonTablePlan
+JsonTablePlanJoinType
+JsonTablePlanType
 JsonTableScanState
 JsonTableSibling
 JsonTokenType