Handle nodes that may appear in GraphPattern expression trees

expression_tree_mutator_impl() did not handle T_GraphPattern,
T_GraphElementPattern, and T_GraphPropertyRef.  The corresponding
expression_tree_walker_impl() already handles all three node types.
This causes an "unrecognized node type" error whenever a GRAPH_TABLE
appeared in an expression tree.

While at it, also update raw_expression_tree_walker() and
expression_tree_walker() to handle missing nodes that may appear in
GraphPattern expression trees.  When raw_expression_tree_walker() is
called, GraphElementPattern::labelexpr contains ColumnRefs instead of
GraphLabelRefs.  Hence those are not handled in
raw_expression_tree_walker().

Author: Satyanarayana Narlapuram <satyanarlapuram@gmail.com>
Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reviewed-by: Robert Haas <robertmhaas@gmail.com>
Discussion: https://www.postgresql.org/message-id/flat/CAHg%2BQDc97WFTSkXg%3Dg_ZAH8GnY2gJrvq72cs%2BYjqEAuZgXnkAQ%40mail.gmail.com

src/backend/nodes/nodeFuncs.c

@@ -2146,6 +2146,7 @@ expression_tree_walker_impl(Node *node,
 		case T_RangeTblRef:
 		case T_SortGroupClause:
 		case T_CTESearchClause:
+		case T_GraphLabelRef:
 		case T_GraphPropertyRef:
 		case T_MergeSupportFunc:
 			/* primitive node types with no expression subnodes */
@@ -2709,6 +2710,8 @@ expression_tree_walker_impl(Node *node,
 			{
 				GraphElementPattern *gep = (GraphElementPattern *) node;
 
+				if (WALK(gep->labelexpr))
+					return true;
 				if (WALK(gep->subexpr))
 					return true;
 				if (WALK(gep->whereClause))
@@ -3072,6 +3075,8 @@ expression_tree_mutator_impl(Node *node,
 		case T_RangeTblRef:
 		case T_SortGroupClause:
 		case T_CTESearchClause:
+		case T_GraphLabelRef:
+		case T_GraphPropertyRef:
 		case T_MergeSupportFunc:
 			return copyObject(node);
 		case T_WithCheckOption:
@@ -3825,6 +3830,30 @@ expression_tree_mutator_impl(Node *node,
 				return (Node *) newnode;
 			}
 			break;
+		case T_GraphElementPattern:
+			{
+				GraphElementPattern *gep = (GraphElementPattern *) node;
+				GraphElementPattern *newnode;
+
+				FLATCOPY(newnode, gep, GraphElementPattern);
+				MUTATE(newnode->labelexpr, gep->labelexpr, Node *);
+				MUTATE(newnode->subexpr, gep->subexpr, List *);
+				MUTATE(newnode->whereClause, gep->whereClause, Node *);
+				newnode->quantifier = list_copy(gep->quantifier);
+				return (Node *) newnode;
+			}
+			break;
+		case T_GraphPattern:
+			{
+				GraphPattern *gp = (GraphPattern *) node;
+				GraphPattern *newnode;
+
+				FLATCOPY(newnode, gp, GraphPattern);
+				MUTATE(newnode->path_pattern_list, gp->path_pattern_list, List *);
+				MUTATE(newnode->whereClause, gp->whereClause, Node *);
+				return (Node *) newnode;
+			}
+			break;
 		default:
 			elog(ERROR, "unrecognized node type: %d",
 				 (int) nodeTag(node));
@@ -4807,6 +4836,8 @@ raw_expression_tree_walker_impl(Node *node,
 			{
 				GraphElementPattern *gep = (GraphElementPattern *) node;
 
+				if (WALK(gep->labelexpr))
+					return true;
 				if (WALK(gep->subexpr))
 					return true;
 				if (WALK(gep->whereClause))

src/test/regress/expected/graph_table.out

@@ -1032,4 +1032,15 @@ SELECT sname, dname FROM GRAPH_TABLE (g1 MATCH (src)->(dest) WHERE src.vprop1 >
 ERROR:  subqueries within GRAPH_TABLE reference are not supported
 SELECT sname, dname FROM GRAPH_TABLE (g1 MATCH (src)->(dest) WHERE out_degree(src.vname) > (SELECT max(out_degree(nname)) FROM GRAPH_TABLE (g1 MATCH (node) COLUMNS (node.vname AS nname))) COLUMNS(src.vname AS sname, dest.vname AS dname));
 ERROR:  subqueries within GRAPH_TABLE reference are not supported
+-- GRAPH_TABLE subquery in HAVING clause (tests expression mutator)
+SELECT src.vname, count(*) FROM v1 AS src
+  GROUP BY src.vname
+  HAVING count(*) >= (SELECT count(*) FROM GRAPH_TABLE (g1 MATCH (a IS vl1 | vl2) COLUMNS (a.vname AS n)) WHERE n = src.vname);
+ vname | count 
+-------+-------
+ v13   |     1
+ v12   |     1
+ v11   |     1
+(3 rows)
+
 -- leave the objects behind for pg_upgrade/pg_dump tests

src/test/regress/sql/graph_table.sql

@@ -590,4 +590,9 @@ SELECT * FROM customers co WHERE co.customer_id = (SELECT customer_id FROM GRAPH
 SELECT sname, dname FROM GRAPH_TABLE (g1 MATCH (src)->(dest) WHERE src.vprop1 > (SELECT max(v1.vprop1) FROM v1) COLUMNS(src.vname AS sname, dest.vname AS dname));
 SELECT sname, dname FROM GRAPH_TABLE (g1 MATCH (src)->(dest) WHERE out_degree(src.vname) > (SELECT max(out_degree(nname)) FROM GRAPH_TABLE (g1 MATCH (node) COLUMNS (node.vname AS nname))) COLUMNS(src.vname AS sname, dest.vname AS dname));
 
+-- GRAPH_TABLE subquery in HAVING clause (tests expression mutator)
+SELECT src.vname, count(*) FROM v1 AS src
+  GROUP BY src.vname
+  HAVING count(*) >= (SELECT count(*) FROM GRAPH_TABLE (g1 MATCH (a IS vl1 | vl2) COLUMNS (a.vname AS n)) WHERE n = src.vname);
+
 -- leave the objects behind for pg_upgrade/pg_dump tests