fix: Remove cypher read clause restriction. (#601)

(cherry picked from commit 21d37de)

src/backend/executor/nodeModifyGraph.c

@@ -366,8 +366,19 @@ ExecModifyGraph(PlanState *pstate)
 
 			/* pass lower bound CID to subplan */
 			svCid = estate->es_snapshot->curcid;
-			estate->es_snapshot->curcid =
-					mgstate->modify_cid + MODIFY_CID_LOWER_BOUND;
+
+			switch (plan->operation)
+			{
+				case GWROP_MERGE:
+				case GWROP_DELETE:
+					estate->es_snapshot->curcid =
+							mgstate->modify_cid + MODIFY_CID_NLJOIN_MATCH;
+					break;
+				default:
+					estate->es_snapshot->curcid =
+							mgstate->modify_cid + MODIFY_CID_LOWER_BOUND;
+					break;
+			}
 
 			slot = ExecProcNode(mgstate->subplan);
 

src/backend/executor/nodeNestloop.c

@@ -110,8 +110,6 @@ ExecNestLoop(PlanState *pstate)
 
 	for (;;)
 	{
-		CommandId	svCid = InvalidCommandId;
-
 		/*
 		 * If we don't have an outer tuple, get the next one and reset the
 		 * inner scan.
@@ -170,19 +168,9 @@ ExecNestLoop(PlanState *pstate)
 		 */
 		ENL1_printf("getting new inner tuple");
 
-		if (node->js.jointype == JOIN_CYPHER_MERGE ||
-			node->js.jointype == JOIN_CYPHER_DELETE)
-		{
-			svCid = innerPlan->state->es_snapshot->curcid;
-			innerPlan->state->es_snapshot->curcid = node->nl_graphwrite_cid;
-		}
-
 		innerTupleSlot = ExecProcNode(innerPlan);
 		econtext->ecxt_innertuple = innerTupleSlot;
 
-		if (svCid != InvalidCommandId)
-			innerPlan->state->es_snapshot->curcid = svCid;
-
 		if (TupIsNull(innerTupleSlot))
 		{
 			ENL1_printf("no inner tuple, need new outer tuple");
@@ -288,7 +276,6 @@ NestLoopState *
 ExecInitNestLoop(NestLoop *node, EState *estate, int eflags)
 {
 	NestLoopState *nlstate;
-	CommandId	svCid = InvalidCommandId;
 
 	/* check for unsupported flags */
 	Assert(!(eflags & (EXEC_FLAG_BACKWARD | EXEC_FLAG_MARK)));
@@ -325,26 +312,8 @@ ExecInitNestLoop(NestLoop *node, EState *estate, int eflags)
 		eflags |= EXEC_FLAG_REWIND;
 	else
 		eflags &= ~EXEC_FLAG_REWIND;
-
-	if (node->join.jointype == JOIN_CYPHER_MERGE ||
-		node->join.jointype == JOIN_CYPHER_DELETE)
-	{
-		/*
-		 * Modify the CID to see the graph pattern created by MERGE CREATE
-		 * or to not see it deleted by DELETE.
-		 */
-		nlstate->nl_graphwrite_cid =
-						estate->es_snapshot->curcid + MODIFY_CID_NLJOIN_MATCH;
-
-		svCid = estate->es_snapshot->curcid;
-		estate->es_snapshot->curcid = nlstate->nl_graphwrite_cid;
-	}
-
 	innerPlanState(nlstate) = ExecInitNode(innerPlan(node), estate, eflags);
 
-	if (svCid != InvalidCommandId)
-		estate->es_snapshot->curcid = svCid;
-
 	/*
 	 * Initialize result slot, type and projection.
 	 */

src/backend/parser/analyze.c

@@ -3038,8 +3038,6 @@ transformCypherStmt(ParseState *pstate, CypherStmt *stmt)
 	CypherClause *clause;
 	NodeTag		type;
 	bool		valid = true;
-	NodeTag		update_type = T_Invalid;
-	bool		read = false;
 
 	clause = (CypherClause *) stmt->last;
 	type = cypherClauseTag(clause);
@@ -3053,7 +3051,6 @@ transformCypherStmt(ParseState *pstate, CypherStmt *stmt)
 		case T_CypherDeleteClause:
 		case T_CypherSetClause:
 		case T_CypherMergeClause:
-			update_type = type;
 			break;
 		default:
 			valid = false;
@@ -3072,7 +3069,13 @@ transformCypherStmt(ParseState *pstate, CypherStmt *stmt)
 		switch (type)
 		{
 			case T_CypherMatchClause:
-				read = true;
+			case T_CypherCreateClause:
+			case T_CypherDeleteClause:
+			case T_CypherSetClause:
+			case T_CypherMergeClause:
+			case T_CypherLoadClause:
+			case T_CypherUnwindClause:
+				/* do nothing. */
 				break;
 			case T_CypherProjection:
 				if (cypherProjectionKind(clause->detail) == CP_RETURN)
@@ -3081,48 +3084,6 @@ transformCypherStmt(ParseState *pstate, CypherStmt *stmt)
 							(errcode(ERRCODE_SYNTAX_ERROR),
 							 errmsg("RETURN must be at the end of the query")));
 				}
-				else
-				{
-					/* CP_WITH */
-					if (update_type != T_Invalid &&
-						update_type != T_CypherCreateClause)
-						read = true;
-				}
-				break;
-			case T_CypherCreateClause:
-				if (update_type == T_Invalid ||
-					update_type == T_CypherMergeClause)
-				{
-					update_type = T_CypherCreateClause;
-				}
-				if (read)
-					ereport(ERROR,
-							(errcode(ERRCODE_SYNTAX_ERROR),
-							 errmsg("Cypher read clauses cannot follow update clauses")));
-				break;
-			case T_CypherDeleteClause:
-			case T_CypherSetClause:
-				if (read)
-					ereport(ERROR,
-							(errcode(ERRCODE_SYNTAX_ERROR),
-							 errmsg("Cypher read clauses cannot follow update clauses")));
-				break;
-			case T_CypherMergeClause:
-				if (update_type == T_Invalid ||
-					update_type == T_CypherCreateClause)
-				{
-					update_type = T_CypherMergeClause;
-				}
-				if (read)
-					ereport(ERROR,
-							(errcode(ERRCODE_SYNTAX_ERROR),
-							 errmsg("Cypher read clauses cannot follow update clauses")));
-				break;
-			case T_CypherLoadClause:
-				read = true;
-				break;
-			case T_CypherUnwindClause:
-				read = true;
 				break;
 			default:
 				elog(ERROR, "unrecognized Cypher clause type: %d", type);

src/test/regress/expected/cypher_dml.out

@@ -2839,7 +2839,10 @@ MATCH (a) DETACH DELETE a;
 -- wrong case
 MERGE (a:v1) MERGE (b:v2 {name: a.notexistent});
 MERGE (a:v1) MATCH (b:v2 {name: a.name}) RETURN a, b;
-ERROR:  Cypher read clauses cannot follow update clauses
+ a | b 
+---+---
+(0 rows)
+
 MERGE (a:v1) MERGE (b:v2 {name: a.name}) MERGE (a);
 ERROR:  duplicate variable "a"
 LINE 1: MERGE (a:v1) MERGE (b:v2 {name: a.name}) MERGE (a);

src/test/regress/expected/cypher_dml2.out

@@ -183,6 +183,51 @@ drop cascades to vlabel v_type
 drop cascades to vlabel v_sub
 drop cascades to elabel e_user_title
 drop cascades to elabel e_title_type
+-- #589 ( Cypher read clauses cannot follow update clauses )
+CREATE GRAPH cypher_dml2;
+SET GRAPH_PATH to cypher_dml2;
+CREATE VLABEL main;
+CREATE ELABEL main2;
+CREATE (n:another {id: 593}) RETURN n.id;
+ id  
+-----
+ 593
+(1 row)
+
+MERGE (n:main {id: 593})
+ON CREATE SET n.id = 593
+WITH n
+MATCH (g: another)
+WHERE g.id = 593
+MERGE (g)-[:main2]->(n);
+MATCH ()-[e:main2]-() RETURN e;
+           e           
+-----------------------
+ main2[4.1][5.1,3.1]{}
+ main2[4.1][5.1,3.1]{}
+(2 rows)
+
+MATCH (g: another) RETURN g;
+            g            
+-------------------------
+ another[5.1]{"id": 593}
+(1 row)
+
+MATCH (g: main) RETURN g;
+          g           
+----------------------
+ main[3.1]{"id": 593}
+(1 row)
+
+DROP GRAPH cypher_dml2 CASCADE;
+NOTICE:  drop cascades to 6 other objects
+DETAIL:  drop cascades to sequence cypher_dml2.ag_label_seq
+drop cascades to vlabel ag_vertex
+drop cascades to elabel ag_edge
+drop cascades to vlabel main
+drop cascades to elabel main2
+drop cascades to vlabel another
+-- fix: Includes necessary JOINs of vertices (#599)
 CREATE GRAPH cypher_dml2;
 SET GRAPH_PATH to cypher_dml2;
 CREATE ({id: 1})-[:e1]->({id: 2})-[:e1]->({id: 3})-[:e1]->({id: 4})

src/test/regress/expected/cypher_eager.out

@@ -520,7 +520,10 @@ MATCH (a) RETURN properties(a);
 -- wrong case
 MERGE (a:v1) MERGE (b:v2 {name: a.notexistent});
 MERGE (a:v1) MATCH (b:v2 {name: a.name}) RETURN a, b;
-ERROR:  Cypher read clauses cannot follow update clauses
+ a | b 
+---+---
+(0 rows)
+
 MERGE (a:v1) MERGE (b:v2 {name: a.name}) MERGE (a);
 ERROR:  duplicate variable "a"
 LINE 1: MERGE (a:v1) MERGE (b:v2 {name: a.name}) MERGE (a);

src/test/regress/sql/cypher_dml2.sql

@@ -110,6 +110,29 @@ SELECT * FROM _trigger_history;
 
 DROP GRAPH cypher_dml2 CASCADE;
 
+-- #589 ( Cypher read clauses cannot follow update clauses )
+CREATE GRAPH cypher_dml2;
+SET GRAPH_PATH to cypher_dml2;
+
+CREATE VLABEL main;
+CREATE ELABEL main2;
+
+CREATE (n:another {id: 593}) RETURN n.id;
+
+MERGE (n:main {id: 593})
+ON CREATE SET n.id = 593
+WITH n
+MATCH (g: another)
+WHERE g.id = 593
+MERGE (g)-[:main2]->(n);
+
+MATCH ()-[e:main2]-() RETURN e;
+MATCH (g: another) RETURN g;
+MATCH (g: main) RETURN g;
+
+DROP GRAPH cypher_dml2 CASCADE;
+
+-- fix: Includes necessary JOINs of vertices (#599)
 CREATE GRAPH cypher_dml2;
 SET GRAPH_PATH to cypher_dml2;