Fix MATCH on brand-new label after CREATE returning 0 rows

regress/expected/cypher_match.out

@@ -3633,6 +3633,91 @@ NOTICE:  graph "issue_2308" has been dropped
 
 (1 row)
 
+--
+-- Issue 2193: CREATE ... WITH ... MATCH on brand-new label returns 0 rows
+-- on first execution because match_check_valid_label() runs before
+-- transform_prev_cypher_clause() creates the label table.
+--
+SELECT create_graph('issue_2193');
+NOTICE:  graph "issue_2193" has been created
+ create_graph 
+--------------
+
+(1 row)
+
+-- Reporter's exact case: CREATE two Person nodes, then MATCH on Person
+-- Should return 2 rows on the very first execution
+SELECT * FROM cypher('issue_2193', $$
+    CREATE (a:Person {name: 'Jane', livesIn: 'London'}),
+           (b:Person {name: 'Tom', livesIn: 'Copenhagen'})
+    WITH a, b
+    MATCH (p:Person)
+    RETURN p.name ORDER BY p.name
+$$) AS (result agtype);
+ result 
+--------
+ "Jane"
+ "Tom"
+(2 rows)
+
+-- Single CREATE + MATCH on brand-new label
+SELECT * FROM cypher('issue_2193', $$
+    CREATE (a:City {name: 'Berlin'})
+    WITH a
+    MATCH (c:City)
+    RETURN c.name
+$$) AS (result agtype);
+  result  
+----------
+ "Berlin"
+(1 row)
+
+-- MATCH on a label that now exists (second execution) still works
+SELECT * FROM cypher('issue_2193', $$
+    CREATE (a:City {name: 'Paris'})
+    WITH a
+    MATCH (c:City)
+    RETURN c.name ORDER BY c.name
+$$) AS (result agtype);
+  result  
+----------
+ "Berlin"
+ "Paris"
+(2 rows)
+
+-- MATCH on non-existent label without DML predecessor still returns 0 rows
+SELECT * FROM cypher('issue_2193', $$
+    MATCH (x:NonExistentLabel)
+    RETURN x
+$$) AS (result agtype);
+ result 
+--------
+(0 rows)
+
+-- MATCH on non-existent label after DML predecessor still returns 0 rows
+-- and MATCH-introduced variable (p) is properly registered
+SELECT * FROM cypher('issue_2193', $$
+    CREATE (a:Person {name: 'Alice'})
+    WITH a
+    MATCH (p:NonExistentLabel)
+    RETURN p
+$$) AS (result agtype);
+ result 
+--------
+(0 rows)
+
+SELECT drop_graph('issue_2193', true);
+NOTICE:  drop cascades to 4 other objects
+DETAIL:  drop cascades to table issue_2193._ag_label_vertex
+drop cascades to table issue_2193._ag_label_edge
+drop cascades to table issue_2193."Person"
+drop cascades to table issue_2193."City"
+NOTICE:  graph "issue_2193" has been dropped
+ drop_graph 
+------------
+
+(1 row)
+
 --
 -- Clean up
 --

regress/sql/cypher_match.sql

@@ -1492,6 +1492,56 @@ $$) AS (val agtype);
 
 SELECT drop_graph('issue_2308', true);
 
+--
+-- Issue 2193: CREATE ... WITH ... MATCH on brand-new label returns 0 rows
+-- on first execution because match_check_valid_label() runs before
+-- transform_prev_cypher_clause() creates the label table.
+--
+SELECT create_graph('issue_2193');
+
+-- Reporter's exact case: CREATE two Person nodes, then MATCH on Person
+-- Should return 2 rows on the very first execution
+SELECT * FROM cypher('issue_2193', $$
+    CREATE (a:Person {name: 'Jane', livesIn: 'London'}),
+           (b:Person {name: 'Tom', livesIn: 'Copenhagen'})
+    WITH a, b
+    MATCH (p:Person)
+    RETURN p.name ORDER BY p.name
+$$) AS (result agtype);
+
+-- Single CREATE + MATCH on brand-new label
+SELECT * FROM cypher('issue_2193', $$
+    CREATE (a:City {name: 'Berlin'})
+    WITH a
+    MATCH (c:City)
+    RETURN c.name
+$$) AS (result agtype);
+
+-- MATCH on a label that now exists (second execution) still works
+SELECT * FROM cypher('issue_2193', $$
+    CREATE (a:City {name: 'Paris'})
+    WITH a
+    MATCH (c:City)
+    RETURN c.name ORDER BY c.name
+$$) AS (result agtype);
+
+-- MATCH on non-existent label without DML predecessor still returns 0 rows
+SELECT * FROM cypher('issue_2193', $$
+    MATCH (x:NonExistentLabel)
+    RETURN x
+$$) AS (result agtype);
+
+-- MATCH on non-existent label after DML predecessor still returns 0 rows
+-- and MATCH-introduced variable (p) is properly registered
+SELECT * FROM cypher('issue_2193', $$
+    CREATE (a:Person {name: 'Alice'})
+    WITH a
+    MATCH (p:NonExistentLabel)
+    RETURN p
+$$) AS (result agtype);
+
+SELECT drop_graph('issue_2193', true);
+
 --
 -- Clean up
 --

src/backend/parser/cypher_clause.c

@@ -2639,7 +2639,15 @@ static Query *transform_cypher_match(cypher_parsestate *cpstate,
     cypher_match *match_self = (cypher_match*) clause->self;
     Node *where = match_self->where;
 
-    if(!match_check_valid_label(match_self, cpstate))
+    /*
+     * Check label validity early unless the predecessor clause chain
+     * contains a data-modifying operation (CREATE, SET, DELETE, MERGE).
+     * DML predecessors may create new labels that are not yet in the
+     * cache, so the check is deferred to after transform_prev_cypher_clause()
+     * for those cases.
+     */
+    if (!clause_chain_has_dml(clause->prev) &&
+        !match_check_valid_label(match_self, cpstate))
     {
         cypher_bool_const *l = make_ag_node(cypher_bool_const);
         cypher_bool_const *r = make_ag_node(cypher_bool_const);
@@ -2949,6 +2957,30 @@ static Query *transform_cypher_match_pattern(cypher_parsestate *cpstate,
              */
             pnsi = get_namespace_item(pstate, rte);
             query->targetList = expandNSItemAttrs(pstate, pnsi, 0, true, -1);
+
+            /*
+             * Now that the predecessor chain is fully transformed and
+             * any CREATE-generated labels exist in the cache, check
+             * whether the MATCH pattern references valid labels. This
+             * deferred check is only needed when the chain has DML,
+             * since labels created by CREATE are not in the cache at
+             * the time of the early check in transform_cypher_match().
+             */
+            if (clause_chain_has_dml(clause->prev) &&
+                !match_check_valid_label(self, cpstate))
+            {
+                cypher_bool_const *l = make_ag_node(cypher_bool_const);
+                cypher_bool_const *r = make_ag_node(cypher_bool_const);
+
+                l->boolean = true;
+                l->location = -1;
+                r->boolean = false;
+                r->location = -1;
+
+                where = (Node *)makeSimpleA_Expr(AEXPR_OP, "=",
+                                                 (Node *)l,
+                                                 (Node *)r, -1);
+            }
         }
 
         transform_match_pattern(cpstate, query, self->pattern, where);