JSON_TABLE: Add support for NESTED paths and columns

A NESTED path allows to extract data from nested levels of JSON objects given by the parent path expression, which are projected as columns specified using a nested COLUMNS clause, just like the parent COLUMNS clause. Rows comprised from a NESTED columns are "joined" to the row comprised from the parent columns. If a particular NESTED path evaluates to 0 rows, then the nested COLUMNS will emit NULLs, making it an OUTER join. NESTED columns themselves may include NESTED paths to allow extracting data from arbitrary nesting levels, which are likewise joined against the rows at the parent level. Multiple NESTED paths at a given level are called "sibling" paths and their rows are combined by UNIONing them, that is, after being joined against the parent row as described above. Author: Nikita Glukhov <n.gluhov@postgrespro.ru> Author: Teodor Sigaev <teodor@sigaev.ru> Author: Oleg Bartunov <obartunov@gmail.com> Author: Alexander Korotkov <aekorotkov@gmail.com> Author: Andrew Dunstan <andrew@dunslane.net> Author: Amit Langote <amitlangote09@gmail.com> Author: Jian He <jian.universality@gmail.com> Reviewers have included (in no particular order): Andres Freund, Alexander Korotkov, Pavel Stehule, Andrew Alsup, Erik Rijkers, Zihong Yu, Himanshu Upadhyaya, Daniel Gustafsson, Justin Pryzby, Álvaro Herrera, Jian He Discussion: https://postgr.es/m/cd0bb935-0158-78a7-08b5-904886deac4b@postgrespro.ru Discussion: https://postgr.es/m/20220616233130.rparivafipt6doj3@alap3.anarazel.de Discussion: https://postgr.es/m/abd9b83b-aa66-f230-3d6d-734817f0995d%40postgresql.org Discussion: https://postgr.es/m/CA+HiwqE4XTdfb1nW=Ojoy_tQSRhYt-q_kb6i5d4xcKyrLC1Nbg@mail.gmail.com
1 year ago · bb766cde63
parent f6a2529920
commit bb766cde63
17 changed files with 1207 additions and 31 deletions
--- a/doc/src/sgml/func.sgml
+++ b/doc/src/sgml/func.sgml
@ -18893,6 +18893,24 @@ DETAIL:  Missing "]" after array dimensions.
   row.
  </para>

+  <para>
+   JSON data stored at a nested level of the row pattern can be extracted using
+   the <literal>NESTED PATH</literal> clause.  Each
+   <literal>NESTED PATH</literal> clause can be used to generate one or more
+   columns using the data from a nested level of the row pattern.  Those
+   columns can be specified using a <literal>COLUMNS</literal> clause that
+   looks similar to the top-level COLUMNS clause.  Rows constructed from
+   NESTED COLUMNS are called <firstterm>child rows</firstterm> and are joined
+   against the row constructed from the columns specified in the parent
+   <literal>COLUMNS</literal> clause to get the row in the final view.  Child
+   columns themselves may contain a <literal>NESTED PATH</literal>
+   specification thus allowing to extract data located at arbitrary nesting
+   levels.  Columns produced by multiple <literal>NESTED PATH</literal>s at the
+   same level are considered to be <firstterm>siblings</firstterm> of each
+   other and their rows after joining with the parent row are combined using
+   UNION.
+  </para>
+
  <para>
   The rows produced by <function>JSON_TABLE</function> are laterally
   joined to the row that generated them, so you do not have to explicitly join
@ -18924,6 +18942,7 @@ where <replaceable class="parameter">json_table_column</replaceable> is:
        <optional> { ERROR | NULL | EMPTY { ARRAY | OBJECT } | DEFAULT <replaceable>expression</replaceable> } ON ERROR </optional>
  | <replaceable>name</replaceable> <replaceable>type</replaceable> EXISTS <optional> PATH <replaceable>path_expression</replaceable> </optional>
        <optional> { ERROR | TRUE | FALSE | UNKNOWN } ON ERROR </optional>
+  | NESTED <optional> PATH </optional> <replaceable>json_path_specification</replaceable> <optional> AS <replaceable>json_path_name</replaceable> </optional> COLUMNS ( <replaceable>json_table_column</replaceable> <optional>, ...</optional> )
 </synopsis>

  <para>
@ -18971,7 +18990,8 @@ where <replaceable class="parameter">json_table_column</replaceable> is:
    <listitem>
    <para>
     Adds an ordinality column that provides sequential row numbering starting
-     from 1.
+     from 1.  Each <literal>NESTED PATH</literal> (see below) gets its own
+     counter for any nested ordinality columns.
    </para>
    </listitem>
   </varlistentry>
@ -19060,6 +19080,33 @@ where <replaceable class="parameter">json_table_column</replaceable> is:
    </note>
      </listitem>
   </varlistentry>
+
+   <varlistentry>
+    <term>
+      <literal>NESTED <optional> PATH </optional></literal> <replaceable>json_path_specification</replaceable> <optional> <literal>AS</literal> <replaceable>json_path_name</replaceable> </optional>
+          <literal>COLUMNS</literal> ( <replaceable>json_table_column</replaceable> <optional>, ...</optional> )
+    </term>
+    <listitem>
+
+    <para>
+     Extracts SQL/JSON values from nested levels of the row pattern,
+     generates one or more columns as defined by the <literal>COLUMNS</literal>
+     subclause, and inserts the extracted SQL/JSON values into those
+     columns.  The <replaceable>json_table_column</replaceable>
+     expression in the <literal>COLUMNS</literal> subclause uses the same
+     syntax as in the parent <literal>COLUMNS</literal> clause.
+    </para>
+
+    <para>
+     The <literal>NESTED PATH</literal> syntax is recursive,
+     so you can go down multiple nested levels by specifying several
+     <literal>NESTED PATH</literal> subclauses within each other.
+     It allows to unnest the hierarchy of JSON objects and arrays
+     in a single function invocation rather than chaining several
+     <function>JSON_TABLE</function> expressions in an SQL statement.
+    </para>
+    </listitem>
+   </varlistentry>
  </variablelist>

   <note>
@ -19189,6 +19236,111 @@ SELECT jt.* FROM
  1 | horror   | Psycho  | "Alfred Hitchcock"
  2 | thriller | Vertigo | "Alfred Hitchcock"
 (2 rows)
+</screen>
+
+     </para>
+     <para>
+      The following is a modified version of the above query to show the usage
+      of <literal>NESTED PATH</literal> for populating title and director
+      columns, illustrating how they are joined to the parent columns id and
+      kind:
+
+<programlisting>
+SELECT jt.* FROM
+ my_films,
+ JSON_TABLE ( js, '$.favorites[*] ? (@.films[*].director == $filter)'
+   PASSING 'Alfred Hitchcock' AS filter
+   COLUMNS (
+    id FOR ORDINALITY,
+    kind text PATH '$.kind',
+    NESTED PATH '$.films[*]' COLUMNS (
+      title text FORMAT JSON PATH '$.title' OMIT QUOTES,
+      director text PATH '$.director' KEEP QUOTES))) AS jt;
+</programlisting>
+
+<screen>
+ id |   kind   |  title  |      director
+----+----------+---------+--------------------
+  1 | horror   | Psycho  | "Alfred Hitchcock"
+  2 | thriller | Vertigo | "Alfred Hitchcock"
+(2 rows)
+</screen>
+
+     </para>
+
+     <para>
+      The following is the same query but without the filter in the root
+      path:
+
+<programlisting>
+SELECT jt.* FROM
+ my_films,
+ JSON_TABLE ( js, '$.favorites[*]'
+   COLUMNS (
+    id FOR ORDINALITY,
+    kind text PATH '$.kind',
+    NESTED PATH '$.films[*]' COLUMNS (
+      title text FORMAT JSON PATH '$.title' OMIT QUOTES,
+      director text PATH '$.director' KEEP QUOTES))) AS jt;
+</programlisting>
+
+<screen>
+ id |   kind   |      title      |      director
+----+----------+-----------------+--------------------
+  1 | comedy   | Bananas         | "Woody Allen"
+  1 | comedy   | The Dinner Game | "Francis Veber"
+  2 | horror   | Psycho          | "Alfred Hitchcock"
+  3 | thriller | Vertigo         | "Alfred Hitchcock"
+  4 | drama    | Yojimbo         | "Akira Kurosawa"
+(5 rows)
+</screen>
+
+     </para>
+
+     <para>
+      The following shows another query using a different <type>JSON</type>
+      object as input.  It shows the UNION "sibling join" between
+      <literal>NESTED</literal> paths <literal>$.movies[*]</literal> and
+      <literal>$.books[*]</literal> and also the usage of
+      <literal>FOR ORDINALITY</literal> column at <literal>NESTED</literal>
+      levels (columns <literal>movie_id</literal>, <literal>book_id</literal>,
+      and <literal>author_id</literal>):
+
+<programlisting>
+SELECT * FROM JSON_TABLE (
+'{"favorites":
+    {"movies":
+      [{"name": "One", "director": "John Doe"},
+       {"name": "Two", "director": "Don Joe"}],
+     "books":
+      [{"name": "Mystery", "authors": [{"name": "Brown Dan"}]},
+       {"name": "Wonder", "authors": [{"name": "Jun Murakami"}, {"name":"Craig Doe"}]}]
+}}'::json, '$.favs[*]'
+COLUMNS (user_id FOR ORDINALITY,
+  NESTED '$.movies[*]'
+    COLUMNS (
+    movie_id FOR ORDINALITY,
+    mname text PATH '$.name',
+    director text),
+  NESTED '$.books[*]'
+    COLUMNS (
+      book_id FOR ORDINALITY,
+      bname text PATH '$.name',
+      NESTED '$.authors[*]'
+        COLUMNS (
+          author_id FOR ORDINALITY,
+          author_name text PATH '$.name'))));
+</programlisting>
+
+<screen>
+ user_id | movie_id | mname | director | book_id |  bname  | author_id | author_name
+---------+----------+-------+----------+---------+---------+-----------+--------------
+       1 |        1 | One   | John Doe |         |         |           |
+       1 |        2 | Two   | Don Joe  |         |         |           |
+       1 |          |       |          |       1 | Mystery |         1 | Brown Dan
+       1 |          |       |          |       2 | Wonder  |         1 | Jun Murakami
+       1 |          |       |          |       2 | Wonder  |         2 | Craig Doe
+(5 rows)
 </screen>

     </para>
--- a/src/backend/catalog/sql_features.txt
+++ b/src/backend/catalog/sql_features.txt
@ -553,7 +553,7 @@ T823	SQL/JSON: PASSING clause			YES
 T824	JSON_TABLE: specific PLAN clause			NO	
 T825	SQL/JSON: ON EMPTY and ON ERROR clauses			YES	
 T826	General value expression in ON ERROR or ON EMPTY clauses			YES	
-T827	JSON_TABLE: sibling NESTED COLUMNS clauses			NO	
+T827	JSON_TABLE: sibling NESTED COLUMNS clauses			YES	
 T828	JSON_QUERY			YES	
 T829	JSON_QUERY: array wrapper options			YES	
 T830	Enforcing unique keys in SQL/JSON constructor functions			YES	
--- a/src/backend/nodes/nodeFuncs.c
+++ b/src/backend/nodes/nodeFuncs.c
@ -4159,6 +4159,8 @@ raw_expression_tree_walker_impl(Node *node,
 					return true;
 				if (WALK(jtc->on_error))
 					return true;
+				if (WALK(jtc->columns))
+					return true;
 			}
 			break;
 		case T_JsonTablePathSpec:
--- a/src/backend/parser/gram.y
+++ b/src/backend/parser/gram.y
@ -755,7 +755,7 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 	MAPPING MATCH MATCHED MATERIALIZED MAXVALUE MERGE MERGE_ACTION METHOD
 	MINUTE_P MINVALUE MODE MONTH_P MOVE

-	NAME_P NAMES NATIONAL NATURAL NCHAR NEW NEXT NFC NFD NFKC NFKD NO
+	NAME_P NAMES NATIONAL NATURAL NCHAR NESTED NEW NEXT NFC NFD NFKC NFKD NO
 	NONE NORMALIZE NORMALIZED
 	NOT NOTHING NOTIFY NOTNULL NOWAIT NULL_P NULLIF
 	NULLS_P NUMERIC
@ -884,8 +884,11 @@ static Node *makeRecursiveViewSelect(char *relname, List *aliases, Node *query);
 * the same precedence as IDENT.  This allows resolving conflicts in the
 * json_predicate_type_constraint and json_key_uniqueness_constraint_opt
 * productions (see comments there).
+ *
+ * Like the UNBOUNDED PRECEDING/FOLLOWING case, NESTED is assigned a lower
+ * precedence than PATH to fix ambiguity in the json_table production.
 */
-%nonassoc	UNBOUNDED /* ideally would have same precedence as IDENT */
+%nonassoc	UNBOUNDED NESTED /* ideally would have same precedence as IDENT */
 %nonassoc	IDENT PARTITION RANGE ROWS GROUPS PRECEDING FOLLOWING CUBE ROLLUP
 			SET KEYS OBJECT_P SCALAR VALUE_P WITH WITHOUT PATH
 %left		Op OPERATOR		/* multi-character ops and user-defined operators */
@ -14270,6 +14273,35 @@ json_table_column_definition:
 					n->location = @1;
 					$$ = (Node *) n;
 				}
+			| NESTED path_opt Sconst
+				COLUMNS '(' json_table_column_definition_list ')'
+				{
+					JsonTableColumn *n = makeNode(JsonTableColumn);
+
+					n->coltype = JTC_NESTED;
+					n->pathspec = (JsonTablePathSpec *)
+						makeJsonTablePathSpec($3, NULL, @3, -1);
+					n->columns = $6;
+					n->location = @1;
+					$$ = (Node *) n;
+				}
+			| NESTED path_opt Sconst AS name
+				COLUMNS '(' json_table_column_definition_list ')'
+				{
+					JsonTableColumn *n = makeNode(JsonTableColumn);
+
+					n->coltype = JTC_NESTED;
+					n->pathspec = (JsonTablePathSpec *)
+						makeJsonTablePathSpec($3, $5, @3, @5);
+					n->columns = $8;
+					n->location = @1;
+					$$ = (Node *) n;
+				}
+		;
+
+path_opt:
+			PATH
+			| /* EMPTY */
 		;

 json_table_column_path_clause_opt:
@ -17688,6 +17720,7 @@ unreserved_keyword:
 			| MOVE
 			| NAME_P
 			| NAMES
+			| NESTED
 			| NEW
 			| NEXT
 			| NFC
@ -18304,6 +18337,7 @@ bare_label_keyword:
 			| NATIONAL
 			| NATURAL
 			| NCHAR
+			| NESTED
 			| NEW
 			| NEXT
 			| NFC
--- a/src/backend/parser/parse_jsontable.c
+++ b/src/backend/parser/parse_jsontable.c
@ -44,16 +44,23 @@ static JsonTablePlan *transformJsonTableColumns(JsonTableParseContext *cxt,
 												List *columns,
 												List *passingArgs,
 												JsonTablePathSpec *pathspec);
+static JsonTablePlan *transformJsonTableNestedColumns(JsonTableParseContext *cxt,
+													  List *passingArgs,
+													  List *columns);
 static JsonFuncExpr *transformJsonTableColumn(JsonTableColumn *jtc,
 											  Node *contextItemExpr,
 											  List *passingArgs);
 static bool isCompositeType(Oid typid);
 static JsonTablePlan *makeJsonTablePathScan(JsonTablePathSpec *pathspec,
-											bool errorOnError);
+											bool errorOnError,
+											int colMin, int colMax,
+											JsonTablePlan *childplan);
 static void CheckDuplicateColumnOrPathNames(JsonTableParseContext *cxt,
 											List *columns);
 static bool LookupPathOrColumnName(JsonTableParseContext *cxt, char *name);
 static char *generateJsonTablePathName(JsonTableParseContext *cxt);
+static JsonTablePlan *makeJsonTableSiblingJoin(JsonTablePlan *lplan,
+											   JsonTablePlan *rplan);

 /*
 * transformJsonTable -
@ -172,13 +179,32 @@ CheckDuplicateColumnOrPathNames(JsonTableParseContext *cxt,
 	{
 		JsonTableColumn *jtc = castNode(JsonTableColumn, lfirst(lc1));

-		if (LookupPathOrColumnName(cxt, jtc->name))
-			ereport(ERROR,
-					errcode(ERRCODE_DUPLICATE_ALIAS),
-					errmsg("duplicate JSON_TABLE column or path name: %s",
-						   jtc->name),
-					parser_errposition(cxt->pstate, jtc->location));
-		cxt->pathNames = lappend(cxt->pathNames, jtc->name);
+		if (jtc->coltype == JTC_NESTED)
+		{
+			if (jtc->pathspec->name)
+			{
+				if (LookupPathOrColumnName(cxt, jtc->pathspec->name))
+					ereport(ERROR,
+							errcode(ERRCODE_DUPLICATE_ALIAS),
+							errmsg("duplicate JSON_TABLE column or path name: %s",
+								   jtc->pathspec->name),
+							parser_errposition(cxt->pstate,
+											   jtc->pathspec->name_location));
+				cxt->pathNames = lappend(cxt->pathNames, jtc->pathspec->name);
+			}
+
+			CheckDuplicateColumnOrPathNames(cxt, jtc->columns);
+		}
+		else
+		{
+			if (LookupPathOrColumnName(cxt, jtc->name))
+				ereport(ERROR,
+						errcode(ERRCODE_DUPLICATE_ALIAS),
+						errmsg("duplicate JSON_TABLE column or path name: %s",
+							   jtc->name),
+						parser_errposition(cxt->pstate, jtc->location));
+			cxt->pathNames = lappend(cxt->pathNames, jtc->name);
+		}
 	}
 }

@ -234,6 +260,12 @@ transformJsonTableColumns(JsonTableParseContext *cxt, List *columns,
 	bool		errorOnError = jt->on_error &&
 		jt->on_error->btype == JSON_BEHAVIOR_ERROR;
 	Oid			contextItemTypid = exprType(tf->docexpr);
+	int			colMin,
+				colMax;
+	JsonTablePlan *childplan;
+
+	/* Start of column range */
+	colMin = list_length(tf->colvalexprs);

 	foreach(col, columns)
 	{
@ -243,9 +275,12 @@ transformJsonTableColumns(JsonTableParseContext *cxt, List *columns,
 		Oid			typcoll = InvalidOid;
 		Node	   *colexpr;

-		Assert(rawc->name);
-		tf->colnames = lappend(tf->colnames,
-							   makeString(pstrdup(rawc->name)));
+		if (rawc->coltype != JTC_NESTED)
+		{
+			Assert(rawc->name);
+			tf->colnames = lappend(tf->colnames,
+								   makeString(pstrdup(rawc->name)));
+		}

 		/*
 		 * Determine the type and typmod for the new column. FOR ORDINALITY
@ -303,6 +338,9 @@ transformJsonTableColumns(JsonTableParseContext *cxt, List *columns,
 					break;
 				}

+			case JTC_NESTED:
+				continue;
+
 			default:
 				elog(ERROR, "unknown JSON_TABLE column type: %d", (int) rawc->coltype);
 				break;
@ -314,7 +352,21 @@ transformJsonTableColumns(JsonTableParseContext *cxt, List *columns,
 		tf->colvalexprs = lappend(tf->colvalexprs, colexpr);
 	}

-	return makeJsonTablePathScan(pathspec, errorOnError);
+	/* End of column range. */
+	if (list_length(tf->colvalexprs) == colMin)
+	{
+		/* No columns in this Scan beside the nested ones. */
+		colMax = colMin = -1;
+	}
+	else
+		colMax = list_length(tf->colvalexprs) - 1;
+
+	/* Recursively transform nested columns */
+	childplan = transformJsonTableNestedColumns(cxt, passingArgs, columns);
+
+	/* Create a "parent" scan responsible for all columns handled above. */
+	return makeJsonTablePathScan(pathspec, errorOnError, colMin, colMax,
+								 childplan);
 }

 /*
@ -396,11 +448,59 @@ transformJsonTableColumn(JsonTableColumn *jtc, Node *contextItemExpr,
 	return jfexpr;
 }

+/*
+ * Recursively transform nested columns and create child plan(s) that will be
+ * used to evaluate their row patterns.
+ */
+static JsonTablePlan *
+transformJsonTableNestedColumns(JsonTableParseContext *cxt,
+								List *passingArgs,
+								List *columns)
+{
+	JsonTablePlan *plan = NULL;
+	ListCell   *lc;
+
+	/*
+	 * If there are multiple NESTED COLUMNS clauses in 'columns', their
+	 * respective plans will be combined using a "sibling join" plan, which
+	 * effectively does a UNION of the sets of rows coming from each nested
+	 * plan.
+	 */
+	foreach(lc, columns)
+	{
+		JsonTableColumn *jtc = castNode(JsonTableColumn, lfirst(lc));
+		JsonTablePlan *nested;
+
+		if (jtc->coltype != JTC_NESTED)
+			continue;
+
+		if (jtc->pathspec->name == NULL)
+			jtc->pathspec->name = generateJsonTablePathName(cxt);
+
+		nested = transformJsonTableColumns(cxt, jtc->columns, passingArgs,
+										   jtc->pathspec);
+
+		if (plan)
+			plan = makeJsonTableSiblingJoin(plan, nested);
+		else
+			plan = nested;
+	}
+
+	return plan;
+}
+
 /*
 * Create a JsonTablePlan for given path and ON ERROR behavior.
+ *
+ * colMin and colMin give the range of columns computed by this scan in the
+ * global flat list of column expressions that will be passed to the
+ * JSON_TABLE's TableFunc.  Both are -1 when all of columns are nested and
+ * thus computed by 'childplan'.
 */
 static JsonTablePlan *
-makeJsonTablePathScan(JsonTablePathSpec *pathspec, bool errorOnError)
+makeJsonTablePathScan(JsonTablePathSpec *pathspec, bool errorOnError,
+					  int colMin, int colMax,
+					  JsonTablePlan *childplan)
 {
 	JsonTablePathScan *scan = makeNode(JsonTablePathScan);
 	char	   *pathstring;
@ -417,5 +517,29 @@ makeJsonTablePathScan(JsonTablePathSpec *pathspec, bool errorOnError)
 	scan->path = makeJsonTablePath(value, pathspec->name);
 	scan->errorOnError = errorOnError;

+	scan->child = childplan;
+
+	scan->colMin = colMin;
+	scan->colMax = colMax;
+
 	return (JsonTablePlan *) scan;
 }
+
+/*
+ * Create a JsonTablePlan that will perform a join of the rows coming from
+ * 'lplan' and 'rplan'.
+ *
+ * The default way of "joining" the rows is to perform a UNION between the
+ * sets of rows from 'lplan' and 'rplan'.
+ */
+static JsonTablePlan *
+makeJsonTableSiblingJoin(JsonTablePlan *lplan, JsonTablePlan *rplan)
+{
+	JsonTableSiblingJoin *join = makeNode(JsonTableSiblingJoin);
+
+	join->plan.type = T_JsonTableSiblingJoin;
+	join->lplan = lplan;
+	join->rplan = rplan;
+
+	return (JsonTablePlan *) join;
+}
--- a/src/backend/utils/adt/jsonpath_exec.c
+++ b/src/backend/utils/adt/jsonpath_exec.c
@ -202,6 +202,18 @@ typedef struct JsonTablePlanState

 	/* Counter for ORDINAL columns */
 	int			ordinal;
+
+	/* Nested plan, if any */
+	struct JsonTablePlanState *nested;
+
+	/* Left sibling, if any */
+	struct JsonTablePlanState *left;
+
+	/* Right sibling, if any */
+	struct JsonTablePlanState *right;
+
+	/* Parent plan, if this is a nested plan */
+	struct JsonTablePlanState *parent;
 } JsonTablePlanState;

 /* Random number to identify JsonTableExecContext for sanity checking */
@ -213,6 +225,12 @@ typedef struct JsonTableExecContext

 	/* State of the plan providing a row evaluated from "root" jsonpath */
 	JsonTablePlanState *rootplanstate;
+
+	/*
+	 * Per-column JsonTablePlanStates for all columns including the nested
+	 * ones.
+	 */
+	JsonTablePlanState **colplanstates;
 } JsonTableExecContext;

 /* strict/lax flags is decomposed into four [un]wrap/error flags */
@ -337,6 +355,7 @@ static void checkTimezoneIsUsedForCast(bool useTz, const char *type1,
 static void JsonTableInitOpaque(TableFuncScanState *state, int natts);
 static JsonTablePlanState *JsonTableInitPlan(JsonTableExecContext *cxt,
 											 JsonTablePlan *plan,
+											 JsonTablePlanState *parentstate,
 											 List *args,
 											 MemoryContext mcxt);
 static void JsonTableSetDocument(TableFuncScanState *state, Datum value);
@ -345,6 +364,9 @@ static bool JsonTableFetchRow(TableFuncScanState *state);
 static Datum JsonTableGetValue(TableFuncScanState *state, int colnum,
 							   Oid typid, int32 typmod, bool *isnull);
 static void JsonTableDestroyOpaque(TableFuncScanState *state);
+static bool JsonTablePlanScanNextRow(JsonTablePlanState *planstate);
+static void JsonTableResetNestedPlan(JsonTablePlanState *planstate);
+static bool JsonTablePlanJoinNextRow(JsonTablePlanState *planstate);
 static bool JsonTablePlanNextRow(JsonTablePlanState *planstate);

 const TableFuncRoutine JsonbTableRoutine =
@ -4087,8 +4109,14 @@ JsonTableInitOpaque(TableFuncScanState *state, int natts)
 		}
 	}

-	/* Initialize plan */
-	cxt->rootplanstate = JsonTableInitPlan(cxt, rootplan, args,
+	cxt->colplanstates = palloc(sizeof(JsonTablePlanState *) *
+								list_length(tf->colvalexprs));
+
+	/*
+	 * Initialize plan for the root path and, recursively, also any child
+	 * plans that compute the NESTED paths.
+	 */
+	cxt->rootplanstate = JsonTableInitPlan(cxt, rootplan, NULL, args,
 										   CurrentMemoryContext);

 	state->opaque = cxt;
@ -4113,19 +4141,22 @@ JsonTableDestroyOpaque(TableFuncScanState *state)
 /*
 * JsonTableInitPlan
 *		Initialize information for evaluating jsonpath in the given
- *		JsonTablePlan
+ *		JsonTablePlan and, recursively, in any child plans
 */
 static JsonTablePlanState *
 JsonTableInitPlan(JsonTableExecContext *cxt, JsonTablePlan *plan,
+				  JsonTablePlanState *parentstate,
 				  List *args, MemoryContext mcxt)
 {
 	JsonTablePlanState *planstate = palloc0(sizeof(*planstate));

 	planstate->plan = plan;
+	planstate->parent = parentstate;

 	if (IsA(plan, JsonTablePathScan))
 	{
 		JsonTablePathScan *scan = (JsonTablePathScan *) plan;
+		int			i;

 		planstate->path = DatumGetJsonPathP(scan->path->value->constvalue);
 		planstate->args = args;
@ -4135,6 +4166,21 @@ JsonTableInitPlan(JsonTableExecContext *cxt, JsonTablePlan *plan,
 		/* No row pattern evaluated yet. */
 		planstate->current.value = PointerGetDatum(NULL);
 		planstate->current.isnull = true;
+
+		for (i = scan->colMin; i >= 0 && i <= scan->colMax; i++)
+			cxt->colplanstates[i] = planstate;
+
+		planstate->nested = scan->child ?
+			JsonTableInitPlan(cxt, scan->child, planstate, args, mcxt) : NULL;
+	}
+	else if (IsA(plan, JsonTableSiblingJoin))
+	{
+		JsonTableSiblingJoin *join = (JsonTableSiblingJoin *) plan;
+
+		planstate->left = JsonTableInitPlan(cxt, join->lplan, parentstate,
+											args, mcxt);
+		planstate->right = JsonTableInitPlan(cxt, join->rplan, parentstate,
+											 args, mcxt);
 	}

 	return planstate;
@ -4193,16 +4239,56 @@ JsonTableResetRowPattern(JsonTablePlanState *planstate, Datum item)
 }

 /*
- * Fetch next row from a JsonTablePlan's path evaluation result.
+ * Fetch next row from a JsonTablePlan.
 *
 * Returns false if the plan has run out of rows, true otherwise.
 */
 static bool
 JsonTablePlanNextRow(JsonTablePlanState *planstate)
 {
-	JsonbValue *jbv = JsonValueListNext(&planstate->found, &planstate->iter);
+	if (IsA(planstate->plan, JsonTablePathScan))
+		return JsonTablePlanScanNextRow(planstate);
+	else if (IsA(planstate->plan, JsonTableSiblingJoin))
+		return JsonTablePlanJoinNextRow(planstate);
+	else
+		elog(ERROR, "invalid JsonTablePlan %d", (int) planstate->plan->type);
+
+	Assert(false);
+	/* Appease compiler */
+	return false;
+}
+
+/*
+ * Fetch next row from a JsonTablePlan's path evaluation result and from
+ * any child nested path(s).
+ *
+ * Returns true if any of the paths (this or the nested) has more rows to
+ * return.
+ *
+ * By fetching the nested path(s)'s rows based on the parent row at each
+ * level, this essentially joins the rows of different levels.  If a nested
+ * path at a given level has no matching rows, the columns of that level will
+ * compute to NULL, making it an OUTER join.
+ */
+static bool
+JsonTablePlanScanNextRow(JsonTablePlanState *planstate)
+{
+	JsonbValue *jbv;
 	MemoryContext oldcxt;

+	/*
+	 * If planstate already has an active row and there is a nested plan,
+	 * check if it has an active row to join with the former.
+	 */
+	if (!planstate->current.isnull)
+	{
+		if (planstate->nested && JsonTablePlanNextRow(planstate->nested))
+			return true;
+	}
+
+	/* Fetch new row from the list of found values to set as active. */
+	jbv = JsonValueListNext(&planstate->found, &planstate->iter);
+
 	/* End of list? */
 	if (jbv == NULL)
 	{
@ -4223,6 +4309,76 @@ JsonTablePlanNextRow(JsonTablePlanState *planstate)
 	/* Next row! */
 	planstate->ordinal++;

+	/* Process nested plan(s), if any. */
+	if (planstate->nested)
+	{
+		/* Re-evaluate the nested path using the above parent row. */
+		JsonTableResetNestedPlan(planstate->nested);
+
+		/*
+		 * Now fetch the nested plan's current row to be joined against the
+		 * parent row.  Any further nested plans' paths will be re-evaluated
+		 * reursively, level at a time, after setting each nested plan's
+		 * current row.
+		 */
+		(void) JsonTablePlanNextRow(planstate->nested);
+	}
+
+	/* There are more rows. */
+	return true;
+}
+
+/*
+ * Re-evaluate the row pattern of a nested plan using the new parent row
+ * pattern.
+ */
+static void
+JsonTableResetNestedPlan(JsonTablePlanState *planstate)
+{
+	/* This better be a child plan. */
+	Assert(planstate->parent != NULL);
+	if (IsA(planstate->plan, JsonTablePathScan))
+	{
+		JsonTablePlanState *parent = planstate->parent;
+
+		if (!parent->current.isnull)
+			JsonTableResetRowPattern(planstate, parent->current.value);
+
+		/*
+		 * If this plan itself has a child nested plan, it will be reset when
+		 * the caller calls JsonTablePlanNextRow() on this plan.
+		 */
+	}
+	else if (IsA(planstate->plan, JsonTableSiblingJoin))
+	{
+		JsonTableResetNestedPlan(planstate->left);
+		JsonTableResetNestedPlan(planstate->right);
+	}
+}
+
+/*
+ * Fetch the next row from a JsonTableSiblingJoin.
+ *
+ * This is essentially a UNION between the rows from left and right siblings.
+ */
+static bool
+JsonTablePlanJoinNextRow(JsonTablePlanState *planstate)
+{
+
+	/* Fetch row from left sibling. */
+	if (!JsonTablePlanNextRow(planstate->left))
+	{
+		/*
+		 * Left sibling ran out of rows, so start fetching from the right
+		 * sibling.
+		 */
+		if (!JsonTablePlanNextRow(planstate->right))
+		{
+			/* Right sibling ran out of row, so there are more rows. */
+			return false;
+		}
+	}
+
 	return true;
 }

@ -4256,7 +4412,7 @@ JsonTableGetValue(TableFuncScanState *state, int colnum,
 		GetJsonTableExecContext(state, "JsonTableGetValue");
 	ExprContext *econtext = state->ss.ps.ps_ExprContext;
 	ExprState  *estate = list_nth(state->colvalexprs, colnum);
-	JsonTablePlanState *planstate = cxt->rootplanstate;
+	JsonTablePlanState *planstate = cxt->colplanstates[colnum];
 	JsonTablePlanRowSource *current = &planstate->current;
 	Datum		result;

--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@ -524,8 +524,13 @@ static char *flatten_reloptions(Oid relid);
 static void get_reloptions(StringInfo buf, Datum reloptions);
 static void get_json_path_spec(Node *path_spec, deparse_context *context,
 							   bool showimplicit);
-static void get_json_table_columns(TableFunc *tf, deparse_context *context,
+static void get_json_table_columns(TableFunc *tf, JsonTablePathScan *scan,
+								   deparse_context *context,
 								   bool showimplicit);
+static void get_json_table_nested_columns(TableFunc *tf, JsonTablePlan *plan,
+										  deparse_context *context,
+										  bool showimplicit,
+										  bool needcomma);

 #define only_marker(rte)  ((rte)->inh ? "" : "ONLY ")

@ -11626,11 +11631,44 @@ get_xmltable(TableFunc *tf, deparse_context *context, bool showimplicit)
 	appendStringInfoChar(buf, ')');
 }

+/*
+ * get_json_nested_columns - Parse back nested JSON_TABLE columns
+ */
+static void
+get_json_table_nested_columns(TableFunc *tf, JsonTablePlan *plan,
+							  deparse_context *context, bool showimplicit,
+							  bool needcomma)
+{
+	if (IsA(plan, JsonTablePathScan))
+	{
+		JsonTablePathScan *scan = castNode(JsonTablePathScan, plan);
+
+		if (needcomma)
+			appendStringInfoChar(context->buf, ',');
+
+		appendStringInfoChar(context->buf, ' ');
+		appendContextKeyword(context, "NESTED PATH ", 0, 0, 0);
+		get_const_expr(scan->path->value, context, -1);
+		appendStringInfo(context->buf, " AS %s", quote_identifier(scan->path->name));
+		get_json_table_columns(tf, scan, context, showimplicit);
+	}
+	else if (IsA(plan, JsonTableSiblingJoin))
+	{
+		JsonTableSiblingJoin *join = (JsonTableSiblingJoin *) plan;
+
+		get_json_table_nested_columns(tf, join->lplan, context, showimplicit,
+									  needcomma);
+		get_json_table_nested_columns(tf, join->rplan, context, showimplicit,
+									  true);
+	}
+}
+
 /*
 * get_json_table_columns - Parse back JSON_TABLE columns
 */
 static void
-get_json_table_columns(TableFunc *tf, deparse_context *context,
+get_json_table_columns(TableFunc *tf, JsonTablePathScan *scan,
+					   deparse_context *context,
 					   bool showimplicit)
 {
 	StringInfo	buf = context->buf;
@ -11663,7 +11701,16 @@ get_json_table_columns(TableFunc *tf, deparse_context *context,
 		typmod = lfirst_int(lc_coltypmod);
 		colexpr = castNode(JsonExpr, lfirst(lc_colvalexpr));

-		if (colnum > 0)
+		/* Skip columns that don't belong to this scan. */
+		if (scan->colMin < 0 || colnum < scan->colMin)
+		{
+			colnum++;
+			continue;
+		}
+		if (colnum > scan->colMax)
+			break;
+
+		if (colnum > scan->colMin)
 			appendStringInfoString(buf, ", ");

 		colnum++;
@ -11711,6 +11758,10 @@ get_json_table_columns(TableFunc *tf, deparse_context *context,
 		get_json_expr_options(colexpr, context, default_behavior);
 	}

+	if (scan->child)
+		get_json_table_nested_columns(tf, scan->child, context, showimplicit,
+									  scan->colMin >= 0);
+
 	if (PRETTY_INDENT(context))
 		context->indentLevel -= PRETTYINDENT_VAR;

@ -11774,7 +11825,8 @@ get_json_table(TableFunc *tf, deparse_context *context, bool showimplicit)
 			context->indentLevel -= PRETTYINDENT_VAR;
 	}

-	get_json_table_columns(tf, context, showimplicit);
+	get_json_table_columns(tf, castNode(JsonTablePathScan, tf->plan), context,
+						   showimplicit);

 	if (jexpr->on_error->btype != JSON_BEHAVIOR_EMPTY)
 		get_json_behavior(jexpr->on_error, context, "ERROR");
--- a/src/include/nodes/parsenodes.h
+++ b/src/include/nodes/parsenodes.h
@ -1844,6 +1844,7 @@ typedef enum JsonTableColumnType
 	JTC_REGULAR,
 	JTC_EXISTS,
 	JTC_FORMATTED,
+	JTC_NESTED,
 } JsonTableColumnType;

 /*
@ -1860,6 +1861,7 @@ typedef struct JsonTableColumn
 	JsonFormat *format;			/* JSON format clause, if specified */
 	JsonWrapper wrapper;		/* WRAPPER behavior for formatted columns */
 	JsonQuotes	quotes;			/* omit or keep quotes on scalar strings? */
+	List	   *columns;		/* nested columns */
 	JsonBehavior *on_empty;		/* ON EMPTY behavior */
 	JsonBehavior *on_error;		/* ON ERROR behavior */
 	int			location;		/* token location, or -1 if unknown */
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@ -1855,7 +1855,10 @@ typedef struct JsonTablePlan
 	NodeTag		type;
 } JsonTablePlan;

-/* JSON_TABLE plan to evaluate a JSON path expression */
+/*
+ * JSON_TABLE plan to evaluate a JSON path expression and NESTED paths, if
+ * any.
+ */
 typedef struct JsonTablePathScan
 {
 	JsonTablePlan plan;
@ -1863,10 +1866,37 @@ typedef struct JsonTablePathScan
 	/* JSON path to evaluate */
 	JsonTablePath *path;

-	/* ERROR/EMPTY ON ERROR behavior */
+	/*
+	 * ERROR/EMPTY ON ERROR behavior; only significant in the plan for the
+	 * top-level path.
+	 */
 	bool		errorOnError;
+
+	/* Plan(s) for nested columns, if any. */
+	JsonTablePlan *child;
+
+	/*
+	 * 0-based index in TableFunc.colvalexprs of the 1st and the last column
+	 * covered by this plan.  Both are -1 if all columns are nested and thus
+	 * computed by the child plan(s).
+	 */
+	int			colMin;
+	int			colMax;
 } JsonTablePathScan;

+/*
+ * JsonTableSiblingJoin -
+ *		Plan to join rows of sibling NESTED COLUMNS clauses in the same parent
+ *		COLUMNS clause
+ */
+typedef struct JsonTableSiblingJoin
+{
+	JsonTablePlan plan;
+
+	JsonTablePlan *lplan;
+	JsonTablePlan *rplan;
+} JsonTableSiblingJoin;
+
 /* ----------------
 * NullTest
 *
--- a/src/include/parser/kwlist.h
+++ b/src/include/parser/kwlist.h
@ -286,6 +286,7 @@ PG_KEYWORD("names", NAMES, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("national", NATIONAL, COL_NAME_KEYWORD, BARE_LABEL)
 PG_KEYWORD("natural", NATURAL, TYPE_FUNC_NAME_KEYWORD, BARE_LABEL)
 PG_KEYWORD("nchar", NCHAR, COL_NAME_KEYWORD, BARE_LABEL)
+PG_KEYWORD("nested", NESTED, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("new", NEW, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("next", NEXT, UNRESERVED_KEYWORD, BARE_LABEL)
 PG_KEYWORD("nfc", NFC, UNRESERVED_KEYWORD, BARE_LABEL)
--- a/src/interfaces/ecpg/test/expected/sql-sqljson_jsontable.c
+++ b/src/interfaces/ecpg/test/expected/sql-sqljson_jsontable.c
@ -132,11 +132,21 @@ if (sqlca.sqlcode < 0) sqlprint();}

  printf("Found foo=%d\n", foo);

+  { ECPGdo(__LINE__, 0, 1, NULL, 0, ECPGst_normal, "select foo from json_table ( jsonb '[{\"foo\":\"1\"}]' , '$[*]' as p0 columns ( nested '$' as p1 columns ( nested path '$' as p11 columns ( foo int ) ) ) ) jt ( foo )", ECPGt_EOIT, 
+	ECPGt_int,&(foo),(long)1,(long)1,sizeof(int), 
+	ECPGt_NO_INDICATOR, NULL , 0L, 0L, 0L, ECPGt_EORT);
+#line 31 "sqljson_jsontable.pgc"
+
+if (sqlca.sqlcode < 0) sqlprint();}
+#line 31 "sqljson_jsontable.pgc"
+
+  printf("Found foo=%d\n", foo);
+
  { ECPGdisconnect(__LINE__, "CURRENT");
-#line 26 "sqljson_jsontable.pgc"
+#line 34 "sqljson_jsontable.pgc"

 if (sqlca.sqlcode < 0) sqlprint();}
-#line 26 "sqljson_jsontable.pgc"
+#line 34 "sqljson_jsontable.pgc"


  return 0;
--- a/src/interfaces/ecpg/test/expected/sql-sqljson_jsontable.stderr
+++ b/src/interfaces/ecpg/test/expected/sql-sqljson_jsontable.stderr
@ -12,5 +12,13 @@
 [NO_PID]: sqlca: code: 0, state: 00000
 [NO_PID]: ecpg_get_data on line 20: RESULT: 1 offset: -1; array: no
 [NO_PID]: sqlca: code: 0, state: 00000
+[NO_PID]: ecpg_execute on line 26: query: select foo from json_table ( jsonb '[{"foo":"1"}]' , '$[*]' as p0 columns ( nested '$' as p1 columns ( nested path '$' as p11 columns ( foo int ) ) ) ) jt ( foo ); with 0 parameter(s) on connection ecpg1_regression
+[NO_PID]: sqlca: code: 0, state: 00000
+[NO_PID]: ecpg_execute on line 26: using PQexec
+[NO_PID]: sqlca: code: 0, state: 00000
+[NO_PID]: ecpg_process_output on line 26: correctly got 1 tuples with 1 fields
+[NO_PID]: sqlca: code: 0, state: 00000
+[NO_PID]: ecpg_get_data on line 26: RESULT: 1 offset: -1; array: no
+[NO_PID]: sqlca: code: 0, state: 00000
 [NO_PID]: ecpg_finish: connection ecpg1_regression closed
 [NO_PID]: sqlca: code: 0, state: 00000
--- a/src/interfaces/ecpg/test/expected/sql-sqljson_jsontable.stdout
+++ b/src/interfaces/ecpg/test/expected/sql-sqljson_jsontable.stdout
@ -1 +1,2 @@
 Found foo=1
+Found foo=1
--- a/src/interfaces/ecpg/test/sql/sqljson_jsontable.pgc
+++ b/src/interfaces/ecpg/test/sql/sqljson_jsontable.pgc
@ -23,6 +23,14 @@ EXEC SQL END DECLARE SECTION;
 	)) jt (foo);
  printf("Found foo=%d\n", foo);

+  EXEC SQL SELECT foo INTO :foo FROM JSON_TABLE(jsonb '[{"foo":"1"}]', '$[*]' AS p0
+	COLUMNS (
+		NESTED '$' AS p1 COLUMNS (
+			NESTED PATH '$' AS p11 COLUMNS ( foo int )
+		)
+	)) jt (foo);
+  printf("Found foo=%d\n", foo);
+
  EXEC SQL DISCONNECT;

  return 0;
--- a/src/test/regress/expected/sqljson_jsontable.out
+++ b/src/test/regress/expected/sqljson_jsontable.out
@ -637,3 +637,388 @@ SELECT * FROM JSON_TABLE(jsonb '{"a": 123}', '$' || '.' || 'a' COLUMNS (foo int)
 ERROR:  only string constants are supported in JSON_TABLE path specification
 LINE 1: SELECT * FROM JSON_TABLE(jsonb '{"a": 123}', '$' || '.' || '...
                                                     ^
+-- JSON_TABLE: nested paths
+-- Duplicate path names
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$' AS a
+	COLUMNS (
+		b int,
+		NESTED PATH '$' AS a
+		COLUMNS (
+			c int
+		)
+	)
+) jt;
+ERROR:  duplicate JSON_TABLE column or path name: a
+LINE 5:   NESTED PATH '$' AS a
+                             ^
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$' AS a
+	COLUMNS (
+		b int,
+		NESTED PATH '$' AS n_a
+		COLUMNS (
+			c int
+		)
+	)
+) jt;
+ b | c 
+---+---
+   |  
+(1 row)
+
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$'
+	COLUMNS (
+		b int,
+		NESTED PATH '$' AS b
+		COLUMNS (
+			c int
+		)
+	)
+) jt;
+ERROR:  duplicate JSON_TABLE column or path name: b
+LINE 5:   NESTED PATH '$' AS b
+                             ^
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$'
+	COLUMNS (
+		NESTED PATH '$' AS a
+		COLUMNS (
+			b int
+		),
+		NESTED PATH '$'
+		COLUMNS (
+			NESTED PATH '$' AS a
+			COLUMNS (
+				c int
+			)
+		)
+	)
+) jt;
+ERROR:  duplicate JSON_TABLE column or path name: a
+LINE 10:    NESTED PATH '$' AS a
+                               ^
+-- JSON_TABLE: plan execution
+CREATE TEMP TABLE jsonb_table_test (js jsonb);
+INSERT INTO jsonb_table_test
+VALUES (
+	'[
+		{"a":  1,  "b": [], "c": []},
+		{"a":  2,  "b": [1, 2, 3], "c": [10, null, 20]},
+		{"a":  3,  "b": [1, 2], "c": []},
+		{"x": "4", "b": [1, 2], "c": 123}
+	 ]'
+);
+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 $.b[*]' as pb columns (b_id for ordinality, b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns (c_id for ordinality, c int path '$' )
+		)
+	) jt;
+ n | a  | b_id | b | c_id | c  
+---+----+------+---+------+----
+ 1 |  1 |      |   |      |   
+ 2 |  2 |    1 | 1 |      |   
+ 2 |  2 |    2 | 2 |      |   
+ 2 |  2 |    3 | 3 |      |   
+ 2 |  2 |      |   |    1 | 10
+ 2 |  2 |      |   |    2 |   
+ 2 |  2 |      |   |    3 | 20
+ 3 |  3 |    1 | 1 |      |   
+ 3 |  3 |    2 | 2 |      |   
+ 4 | -1 |    1 | 1 |      |   
+ 4 | -1 |    2 | 2 |      |   
+(11 rows)
+
+-- PASSING arguments are passed to nested paths and their columns' paths
+SELECT *
+FROM
+	generate_series(1, 3) x,
+	generate_series(1, 3) y,
+	JSON_TABLE(jsonb
+		'[[1,2,3],[2,3,4,5],[3,4,5,6]]',
+		'strict $[*] ? (@[*] <= $x)'
+		PASSING x AS x, y AS y
+		COLUMNS (
+			y text FORMAT JSON PATH '$',
+			NESTED PATH 'strict $[*] ? (@ == $y)'
+			COLUMNS (
+				z int PATH '$'
+			)
+		)
+	) jt;
+ x | y |      y       | z 
+---+---+--------------+---
+ 1 | 1 | [1, 2, 3]    | 1
+ 2 | 1 | [1, 2, 3]    | 1
+ 2 | 1 | [2, 3, 4, 5] |  
+ 3 | 1 | [1, 2, 3]    | 1
+ 3 | 1 | [2, 3, 4, 5] |  
+ 3 | 1 | [3, 4, 5, 6] |  
+ 1 | 2 | [1, 2, 3]    | 2
+ 2 | 2 | [1, 2, 3]    | 2
+ 2 | 2 | [2, 3, 4, 5] | 2
+ 3 | 2 | [1, 2, 3]    | 2
+ 3 | 2 | [2, 3, 4, 5] | 2
+ 3 | 2 | [3, 4, 5, 6] |  
+ 1 | 3 | [1, 2, 3]    | 3
+ 2 | 3 | [1, 2, 3]    | 3
+ 2 | 3 | [2, 3, 4, 5] | 3
+ 3 | 3 | [1, 2, 3]    | 3
+ 3 | 3 | [2, 3, 4, 5] | 3
+ 3 | 3 | [3, 4, 5, 6] | 3
+(18 rows)
+
+-- JSON_TABLE: Test backward parsing with nested paths
+CREATE VIEW jsonb_table_view_nested AS
+SELECT * FROM
+	JSON_TABLE(
+		jsonb 'null', 'lax $[*]' PASSING 1 + 2 AS a, json '"foo"' AS "b c"
+		COLUMNS (
+			id FOR ORDINALITY,
+			NESTED PATH '$[1]' AS p1 COLUMNS (
+				a1 int,
+				NESTED PATH '$[*]' AS "p1 1" COLUMNS (
+					a11 text
+				),
+				b1 text
+			),
+			NESTED PATH '$[2]' AS p2 COLUMNS (
+				NESTED PATH '$[*]' AS "p2:1" COLUMNS (
+					a21 text
+				),
+				NESTED PATH '$[*]' AS p22 COLUMNS (
+					a22 text
+				)
+			)
+		)
+	);
+\sv jsonb_table_view_nested
+CREATE OR REPLACE VIEW public.jsonb_table_view_nested AS
+ SELECT id,
+    a1,
+    b1,
+    a11,
+    a21,
+    a22
+   FROM JSON_TABLE(
+            'null'::jsonb, '$[*]' AS json_table_path_0
+            PASSING
+                1 + 2 AS a,
+                '"foo"'::json AS "b c"
+            COLUMNS (
+                id FOR ORDINALITY,
+                NESTED PATH '$[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 '$."a22"'
+                    )
+                )
+            )
+        )
+DROP VIEW jsonb_table_view_nested;
+CREATE TABLE s (js jsonb);
+INSERT INTO s VALUES
+	('{"a":{"za":[{"z1": [11,2222]},{"z21": [22, 234,2345]},{"z22": [32, 204,145]}]},"c": 3}'),
+	('{"a":{"za":[{"z1": [21,4222]},{"z21": [32, 134,1345]}]},"c": 10}');
+-- error
+SELECT sub.* FROM s,
+	JSON_TABLE(js, '$' PASSING 32 AS x, 13 AS y COLUMNS (
+		xx int path '$.c',
+		NESTED PATH '$.a.za[1]' columns (NESTED PATH '$.z21[*]' COLUMNS (z21 int path '$?(@ >= $"x")' ERROR ON ERROR))
+	)) sub;
+ERROR:  no SQL/JSON item
+-- Parent columns xx1, xx appear before NESTED ones
+SELECT sub.* FROM s,
+	(VALUES (23)) x(x), generate_series(13, 13) y,
+	JSON_TABLE(js, '$' AS c1 PASSING x AS x, y AS y COLUMNS (
+		NESTED PATH '$.a.za[2]' COLUMNS (
+			NESTED PATH '$.z22[*]' as z22 COLUMNS (c int PATH '$')),
+			NESTED PATH '$.a.za[1]' columns (d int[] PATH '$.z21'),
+			NESTED PATH '$.a.za[0]' columns (NESTED PATH '$.z1[*]' as z1 COLUMNS (a int PATH  '$')),
+			xx1 int PATH '$.c',
+			NESTED PATH '$.a.za[1]'  columns (NESTED PATH '$.z21[*]' as z21 COLUMNS (b int PATH '$')),
+			xx int PATH '$.c'
+	)) sub;
+ xx1 | xx |  c  |       d       |  a   |  b   
+-----+----+-----+---------------+------+------
+   3 |  3 |  32 |               |      |     
+   3 |  3 | 204 |               |      |     
+   3 |  3 | 145 |               |      |     
+   3 |  3 |     | {22,234,2345} |      |     
+   3 |  3 |     |               |   11 |     
+   3 |  3 |     |               | 2222 |     
+   3 |  3 |     |               |      |   22
+   3 |  3 |     |               |      |  234
+   3 |  3 |     |               |      | 2345
+  10 | 10 |     | {32,134,1345} |      |     
+  10 | 10 |     |               |   21 |     
+  10 | 10 |     |               | 4222 |     
+  10 | 10 |     |               |      |   32
+  10 | 10 |     |               |      |  134
+  10 | 10 |     |               |      | 1345
+(15 rows)
+
+-- Test applying PASSING variables at different nesting levels
+SELECT sub.* FROM s,
+	(VALUES (23)) x(x), generate_series(13, 13) y,
+	JSON_TABLE(js, '$' AS c1 PASSING x AS x, y AS y COLUMNS (
+		xx1 int PATH '$.c',
+		NESTED PATH '$.a.za[0].z1[*]' COLUMNS (NESTED PATH '$ ?(@ >= ($"x" -2))' COLUMNS (a int PATH '$')),
+		NESTED PATH '$.a.za[0]' COLUMNS (NESTED PATH '$.z1[*] ? (@ >= ($"x" -2))' COLUMNS (b int PATH '$'))
+	)) sub;
+ xx1 |  a   |  b   
+-----+------+------
+   3 |      |     
+   3 | 2222 |     
+   3 |      | 2222
+  10 |   21 |     
+  10 | 4222 |     
+  10 |      |   21
+  10 |      | 4222
+(7 rows)
+
+-- Test applying PASSING variable to paths all the levels
+SELECT sub.* FROM s,
+	(VALUES (23)) x(x),
+	generate_series(13, 13) y,
+	JSON_TABLE(js, '$' AS c1 PASSING x AS x, y AS y
+	COLUMNS (
+		xx1 int PATH '$.c',
+		NESTED PATH '$.a.za[1]'
+			COLUMNS (NESTED PATH '$.z21[*]' COLUMNS (b int PATH '$')),
+		NESTED PATH '$.a.za[1] ? (@.z21[*] >= ($"x"-1))' COLUMNS
+			(NESTED PATH '$.z21[*] ? (@ >= ($"y" + 3))' as z22 COLUMNS (a int PATH '$ ? (@ >= ($"y" + 12))')),
+		NESTED PATH '$.a.za[1]' COLUMNS
+			(NESTED PATH '$.z21[*] ? (@ >= ($"y" +121))' as z21 COLUMNS (c int PATH '$ ? (@ > ($"x" +111))'))
+	)) sub;
+ xx1 |  b   |  a   |  c   
+-----+------+------+------
+   3 |   22 |      |     
+   3 |  234 |      |     
+   3 | 2345 |      |     
+   3 |      |      |     
+   3 |      |  234 |     
+   3 |      | 2345 |     
+   3 |      |      |  234
+   3 |      |      | 2345
+  10 |   32 |      |     
+  10 |  134 |      |     
+  10 | 1345 |      |     
+  10 |      |   32 |     
+  10 |      |  134 |     
+  10 |      | 1345 |     
+  10 |      |      |     
+  10 |      |      | 1345
+(16 rows)
+
+----- test on empty behavior
+SELECT sub.* FROM s,
+	(values(23)) x(x),
+	generate_series(13, 13) y,
+	JSON_TABLE(js, '$' AS c1 PASSING x AS x, y AS y
+	COLUMNS (
+		xx1 int PATH '$.c',
+		NESTED PATH '$.a.za[2]' COLUMNS (NESTED PATH '$.z22[*]' as z22 COLUMNS (c int PATH '$')),
+		NESTED PATH '$.a.za[1]' COLUMNS (d json PATH '$ ? (@.z21[*] == ($"x" -1))'),
+		NESTED PATH '$.a.za[0]' COLUMNS (NESTED PATH '$.z1[*] ? (@ >= ($"x" -2))' as z1 COLUMNS (a int PATH '$')),
+		NESTED PATH '$.a.za[1]' COLUMNS
+			(NESTED PATH '$.z21[*] ? (@ >= ($"y" +121))' as z21 COLUMNS (b int PATH '$ ? (@ > ($"x" +111))' DEFAULT 0 ON EMPTY))
+	)) sub;
+ xx1 |  c  |            d             |  a   |  b   
+-----+-----+--------------------------+------+------
+   3 |  32 |                          |      |     
+   3 | 204 |                          |      |     
+   3 | 145 |                          |      |     
+   3 |     | {"z21": [22, 234, 2345]} |      |     
+   3 |     |                          | 2222 |     
+   3 |     |                          |      |  234
+   3 |     |                          |      | 2345
+  10 |     |                          |      |     
+  10 |     |                          |   21 |     
+  10 |     |                          | 4222 |     
+  10 |     |                          |      |    0
+  10 |     |                          |      | 1345
+(12 rows)
+
+CREATE OR REPLACE VIEW jsonb_table_view7 AS
+SELECT sub.* FROM s,
+	(values(23)) x(x),
+	generate_series(13, 13) y,
+	JSON_TABLE(js, '$' AS c1 PASSING x AS x, y AS y
+	COLUMNS (
+		xx1 int PATH '$.c',
+		NESTED PATH '$.a.za[2]' COLUMNS (NESTED PATH '$.z22[*]' as z22 COLUMNS (c int PATH '$' WITHOUT WRAPPER OMIT QUOTES)),
+		NESTED PATH '$.a.za[1]' COLUMNS (d json PATH '$ ? (@.z21[*] == ($"x" -1))' WITH WRAPPER),
+		NESTED PATH '$.a.za[0]' COLUMNS (NESTED PATH '$.z1[*] ? (@ >= ($"x" -2))' as z1 COLUMNS (a int PATH '$' KEEP QUOTES)),
+		NESTED PATH '$.a.za[1]' COLUMNS
+			(NESTED PATH '$.z21[*] ? (@ >= ($"y" +121))' as z21 COLUMNS (b int PATH '$ ? (@ > ($"x" +111))' DEFAULT 0 ON EMPTY))
+	)) sub;
+\sv jsonb_table_view7
+CREATE OR REPLACE VIEW public.jsonb_table_view7 AS
+ SELECT sub.xx1,
+    sub.c,
+    sub.d,
+    sub.a,
+    sub.b
+   FROM s,
+    ( VALUES (23)) x(x),
+    generate_series(13, 13) y(y),
+    LATERAL JSON_TABLE(
+            s.js, '$' AS c1
+            PASSING
+                x.x AS x,
+                y.y AS y
+            COLUMNS (
+                xx1 integer PATH '$."c"',
+                NESTED PATH '$."a"."za"[2]' AS json_table_path_0
+                COLUMNS (
+                    NESTED PATH '$."z22"[*]' AS z22
+                    COLUMNS (
+                        c integer PATH '$' WITHOUT WRAPPER OMIT QUOTES
+                    )
+                ),
+                NESTED PATH '$."a"."za"[1]' AS json_table_path_1
+                COLUMNS (
+                    d json PATH '$?(@."z21"[*] == $"x" - 1)' WITH UNCONDITIONAL WRAPPER KEEP QUOTES
+                ),
+                NESTED PATH '$."a"."za"[0]' AS json_table_path_2
+                COLUMNS (
+                    NESTED PATH '$."z1"[*]?(@ >= $"x" - 2)' AS z1
+                    COLUMNS (
+                        a integer PATH '$' WITHOUT WRAPPER KEEP QUOTES
+                    )
+                ),
+                NESTED PATH '$."a"."za"[1]' AS json_table_path_3
+                COLUMNS (
+                    NESTED PATH '$."z21"[*]?(@ >= $"y" + 121)' AS z21
+                    COLUMNS (
+                        b integer PATH '$?(@ > $"x" + 111)' DEFAULT 0 ON EMPTY
+                    )
+                )
+            )
+        ) sub
+DROP VIEW jsonb_table_view7;
+DROP TABLE s;
--- a/src/test/regress/sql/sqljson_jsontable.sql
+++ b/src/test/regress/sql/sqljson_jsontable.sql
@ -289,3 +289,213 @@ FROM JSON_TABLE(

 -- Should fail (not supported)
 SELECT * FROM JSON_TABLE(jsonb '{"a": 123}', '$' || '.' || 'a' COLUMNS (foo int));
+
+-- JSON_TABLE: nested paths
+
+-- Duplicate path names
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$' AS a
+	COLUMNS (
+		b int,
+		NESTED PATH '$' AS a
+		COLUMNS (
+			c int
+		)
+	)
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$' AS a
+	COLUMNS (
+		b int,
+		NESTED PATH '$' AS n_a
+		COLUMNS (
+			c int
+		)
+	)
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$'
+	COLUMNS (
+		b int,
+		NESTED PATH '$' AS b
+		COLUMNS (
+			c int
+		)
+	)
+) jt;
+
+SELECT * FROM JSON_TABLE(
+	jsonb '[]', '$'
+	COLUMNS (
+		NESTED PATH '$' AS a
+		COLUMNS (
+			b int
+		),
+		NESTED PATH '$'
+		COLUMNS (
+			NESTED PATH '$' AS a
+			COLUMNS (
+				c int
+			)
+		)
+	)
+) jt;
+
+
+-- JSON_TABLE: plan execution
+
+CREATE TEMP TABLE jsonb_table_test (js jsonb);
+
+INSERT INTO jsonb_table_test
+VALUES (
+	'[
+		{"a":  1,  "b": [], "c": []},
+		{"a":  2,  "b": [1, 2, 3], "c": [10, null, 20]},
+		{"a":  3,  "b": [1, 2], "c": []},
+		{"x": "4", "b": [1, 2], "c": 123}
+	 ]'
+);
+
+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 $.b[*]' as pb columns (b_id for ordinality, b int path '$' ),
+			nested path 'strict $.c[*]' as pc columns (c_id for ordinality, c int path '$' )
+		)
+	) jt;
+
+
+-- PASSING arguments are passed to nested paths and their columns' paths
+SELECT *
+FROM
+	generate_series(1, 3) x,
+	generate_series(1, 3) y,
+	JSON_TABLE(jsonb
+		'[[1,2,3],[2,3,4,5],[3,4,5,6]]',
+		'strict $[*] ? (@[*] <= $x)'
+		PASSING x AS x, y AS y
+		COLUMNS (
+			y text FORMAT JSON PATH '$',
+			NESTED PATH 'strict $[*] ? (@ == $y)'
+			COLUMNS (
+				z int PATH '$'
+			)
+		)
+	) jt;
+
+-- JSON_TABLE: Test backward parsing with nested paths
+
+CREATE VIEW jsonb_table_view_nested AS
+SELECT * FROM
+	JSON_TABLE(
+		jsonb 'null', 'lax $[*]' PASSING 1 + 2 AS a, json '"foo"' AS "b c"
+		COLUMNS (
+			id FOR ORDINALITY,
+			NESTED PATH '$[1]' AS p1 COLUMNS (
+				a1 int,
+				NESTED PATH '$[*]' AS "p1 1" COLUMNS (
+					a11 text
+				),
+				b1 text
+			),
+			NESTED PATH '$[2]' AS p2 COLUMNS (
+				NESTED PATH '$[*]' AS "p2:1" COLUMNS (
+					a21 text
+				),
+				NESTED PATH '$[*]' AS p22 COLUMNS (
+					a22 text
+				)
+			)
+		)
+	);
+
+\sv jsonb_table_view_nested
+DROP VIEW jsonb_table_view_nested;
+
+CREATE TABLE s (js jsonb);
+INSERT INTO s VALUES
+	('{"a":{"za":[{"z1": [11,2222]},{"z21": [22, 234,2345]},{"z22": [32, 204,145]}]},"c": 3}'),
+	('{"a":{"za":[{"z1": [21,4222]},{"z21": [32, 134,1345]}]},"c": 10}');
+
+-- error
+SELECT sub.* FROM s,
+	JSON_TABLE(js, '$' PASSING 32 AS x, 13 AS y COLUMNS (
+		xx int path '$.c',
+		NESTED PATH '$.a.za[1]' columns (NESTED PATH '$.z21[*]' COLUMNS (z21 int path '$?(@ >= $"x")' ERROR ON ERROR))
+	)) sub;
+
+-- Parent columns xx1, xx appear before NESTED ones
+SELECT sub.* FROM s,
+	(VALUES (23)) x(x), generate_series(13, 13) y,
+	JSON_TABLE(js, '$' AS c1 PASSING x AS x, y AS y COLUMNS (
+		NESTED PATH '$.a.za[2]' COLUMNS (
+			NESTED PATH '$.z22[*]' as z22 COLUMNS (c int PATH '$')),
+			NESTED PATH '$.a.za[1]' columns (d int[] PATH '$.z21'),
+			NESTED PATH '$.a.za[0]' columns (NESTED PATH '$.z1[*]' as z1 COLUMNS (a int PATH  '$')),
+			xx1 int PATH '$.c',
+			NESTED PATH '$.a.za[1]'  columns (NESTED PATH '$.z21[*]' as z21 COLUMNS (b int PATH '$')),
+			xx int PATH '$.c'
+	)) sub;
+
+-- Test applying PASSING variables at different nesting levels
+SELECT sub.* FROM s,
+	(VALUES (23)) x(x), generate_series(13, 13) y,
+	JSON_TABLE(js, '$' AS c1 PASSING x AS x, y AS y COLUMNS (
+		xx1 int PATH '$.c',
+		NESTED PATH '$.a.za[0].z1[*]' COLUMNS (NESTED PATH '$ ?(@ >= ($"x" -2))' COLUMNS (a int PATH '$')),
+		NESTED PATH '$.a.za[0]' COLUMNS (NESTED PATH '$.z1[*] ? (@ >= ($"x" -2))' COLUMNS (b int PATH '$'))
+	)) sub;
+
+-- Test applying PASSING variable to paths all the levels
+SELECT sub.* FROM s,
+	(VALUES (23)) x(x),
+	generate_series(13, 13) y,
+	JSON_TABLE(js, '$' AS c1 PASSING x AS x, y AS y
+	COLUMNS (
+		xx1 int PATH '$.c',
+		NESTED PATH '$.a.za[1]'
+			COLUMNS (NESTED PATH '$.z21[*]' COLUMNS (b int PATH '$')),
+		NESTED PATH '$.a.za[1] ? (@.z21[*] >= ($"x"-1))' COLUMNS
+			(NESTED PATH '$.z21[*] ? (@ >= ($"y" + 3))' as z22 COLUMNS (a int PATH '$ ? (@ >= ($"y" + 12))')),
+		NESTED PATH '$.a.za[1]' COLUMNS
+			(NESTED PATH '$.z21[*] ? (@ >= ($"y" +121))' as z21 COLUMNS (c int PATH '$ ? (@ > ($"x" +111))'))
+	)) sub;
+
+----- test on empty behavior
+SELECT sub.* FROM s,
+	(values(23)) x(x),
+	generate_series(13, 13) y,
+	JSON_TABLE(js, '$' AS c1 PASSING x AS x, y AS y
+	COLUMNS (
+		xx1 int PATH '$.c',
+		NESTED PATH '$.a.za[2]' COLUMNS (NESTED PATH '$.z22[*]' as z22 COLUMNS (c int PATH '$')),
+		NESTED PATH '$.a.za[1]' COLUMNS (d json PATH '$ ? (@.z21[*] == ($"x" -1))'),
+		NESTED PATH '$.a.za[0]' COLUMNS (NESTED PATH '$.z1[*] ? (@ >= ($"x" -2))' as z1 COLUMNS (a int PATH '$')),
+		NESTED PATH '$.a.za[1]' COLUMNS
+			(NESTED PATH '$.z21[*] ? (@ >= ($"y" +121))' as z21 COLUMNS (b int PATH '$ ? (@ > ($"x" +111))' DEFAULT 0 ON EMPTY))
+	)) sub;
+
+CREATE OR REPLACE VIEW jsonb_table_view7 AS
+SELECT sub.* FROM s,
+	(values(23)) x(x),
+	generate_series(13, 13) y,
+	JSON_TABLE(js, '$' AS c1 PASSING x AS x, y AS y
+	COLUMNS (
+		xx1 int PATH '$.c',
+		NESTED PATH '$.a.za[2]' COLUMNS (NESTED PATH '$.z22[*]' as z22 COLUMNS (c int PATH '$' WITHOUT WRAPPER OMIT QUOTES)),
+		NESTED PATH '$.a.za[1]' COLUMNS (d json PATH '$ ? (@.z21[*] == ($"x" -1))' WITH WRAPPER),
+		NESTED PATH '$.a.za[0]' COLUMNS (NESTED PATH '$.z1[*] ? (@ >= ($"x" -2))' as z1 COLUMNS (a int PATH '$' KEEP QUOTES)),
+		NESTED PATH '$.a.za[1]' COLUMNS
+			(NESTED PATH '$.z21[*] ? (@ >= ($"y" +121))' as z21 COLUMNS (b int PATH '$ ? (@ > ($"x" +111))' DEFAULT 0 ON EMPTY))
+	)) sub;
+\sv jsonb_table_view7
+DROP VIEW jsonb_table_view7;
+DROP TABLE s;
--- a/src/tools/pgindent/typedefs.list
+++ b/src/tools/pgindent/typedefs.list
@ -1358,6 +1358,7 @@ JsonTablePathSpec
 JsonTablePlan
 JsonTablePlanRowSource
 JsonTablePlanState
+JsonTableSiblingJoin
 JsonTokenType
 JsonTransformStringValuesAction
 JsonTypeCategory