v20260703-0003-Report-duplicate-property-and-label-names-.patch

From 9758fdad9c71e36e26a10350ad01102f7288d42e Mon Sep 17 00:00:00 2001
From: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Date: Thu, 2 Jul 2026 15:27:15 +0530
Subject: [PATCH v20260703 03/14] Report duplicate property and label names
 with a proper error

Adding a property with the same name multiple times to a label on an
element, either within a single PROPERTIES clause or across statements
via ALTER PROPERTY GRAPH ... ADD PROPERTIES, previously failed with a
unique-index violation on pg_propgraph_label_property. The same class
of bug existed for labels: listing the same label multiple times on one
element in CREATE PROPERTY GRAPH, or adding a label to an element that
already has it via ALTER PROPERTY GRAPH ... ADD LABEL, failed with a
unique-index violation on pg_propgraph_element_label. Detect the
duplicates up front and raise a friendlier error in both cases.

For properties, the cross-statement duplicate is caught by a syscache
probe before insertion. The in-clause duplicate could have been caught
by the same probe if we issued a CommandCounterIncrement() between
property inserts, but that forces a catalog invalidation per property
purely to detect a condition we can check for free on the in-memory
target list. The list-based check is only needed when the properties
are listed explicitly; when they are derived from the table's
attributes, names are already unique.

For labels, a single syscache probe on pg_propgraph_element_label
suffices for both the in-clause and cross-statement cases because
insert_element_record() already issues CommandCounterIncrement()
between successive label inserts.

Add regression tests exercising both bugs, and extend the existing
alter-propgraph-concurrently isolation spec with permutations that add
the same property, and the same label, from two concurrent sessions;
the second session now sees the friendly duplicate-object error rather
than a unique-index violation.

Author: Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>
Reported by: Noah Misch <noah@leadboat.com>
Discussion: https://www.postgresql.org/message-id/20260630173053.51.noahmisch@microsoft.com
---
 src/backend/commands/propgraphcmds.c          | 37 ++++++++++-
 .../expected/alter-propgraph-concurrently.out | 66 +++++++++++++++++++
 .../specs/alter-propgraph-concurrently.spec   | 14 ++++
 .../expected/create_property_graph.out        | 14 ++++
 .../regress/sql/create_property_graph.sql     | 12 ++++
 5 files changed, 140 insertions(+), 3 deletions(-)

diff --git a/src/backend/commands/propgraphcmds.c b/src/backend/commands/propgraphcmds.c
index 62f91a08410..4c0fe763b5c 100644
--- a/src/backend/commands/propgraphcmds.c
+++ b/src/backend/commands/propgraphcmds.c
@@ -784,6 +784,13 @@ insert_label_record(Oid graphid, Oid peoid, const char *label)
 	/*
 	 * Insert into pg_propgraph_element_label
 	 */
+	if (SearchSysCacheExists2(PROPGRAPHELEMENTLABELELEMENTLABEL,
+							  ObjectIdGetDatum(peoid),
+							  ObjectIdGetDatum(labeloid)))
+		ereport(ERROR,
+				errcode(ERRCODE_DUPLICATE_OBJECT),
+				errmsg("label \"%s\" already exists", label));
+	else
 	{
 		Relation	rel;
 		Datum		values[Natts_pg_propgraph_element_label] = {0};
@@ -899,12 +906,30 @@ insert_property_records(Oid graphid, Oid ellabeloid, Oid pgerelid, const PropGra
 	tp = transformTargetList(pstate, proplist, EXPR_KIND_PROPGRAPH_PROPERTY);
 	assign_expr_collations(pstate, (Node *) tp);
 
-	foreach(lc, tp)
+	/*
+	 * When properties are derived from the table's attributes, names are
+	 * already unique. Reject duplicate property names within an explicit
+	 * PROPERTIES clause. Do this after transformTargetList() so that any
+	 * names derived by transformTargetList() are considered.
+	 */
+	if (!properties->all)
 	{
-		TargetEntry *te = lfirst_node(TargetEntry, lc);
+		List	   *seen = NIL;
 
-		insert_property_record(graphid, ellabeloid, pgerelid, te->resname, te->expr);
+		foreach_node(TargetEntry, te, tp)
+		{
+			String	   *name = makeString(te->resname);
+
+			if (list_member(seen, name))
+				ereport(ERROR,
+						errcode(ERRCODE_DUPLICATE_OBJECT),
+						errmsg("property \"%s\" specified more than once", te->resname));
+			seen = lappend(seen, name);
+		}
 	}
+
+	foreach_node(TargetEntry, te, tp)
+		insert_property_record(graphid, ellabeloid, pgerelid, te->resname, te->expr);
 }
 
 /*
@@ -1001,6 +1026,12 @@ insert_property_record(Oid graphid, Oid ellabeloid, Oid pgerelid, const char *pr
 	/*
 	 * Insert into pg_propgraph_label_property
 	 */
+	if (SearchSysCacheExists2(PROPGRAPHLABELPROP, ObjectIdGetDatum(ellabeloid),
+							  ObjectIdGetDatum(propoid)))
+		ereport(ERROR,
+				errcode(ERRCODE_DUPLICATE_OBJECT),
+				errmsg("property \"%s\" already exists", propname));
+	else
 	{
 		Relation	rel;
 		Datum		values[Natts_pg_propgraph_label_property] = {0};
diff --git a/src/test/isolation/expected/alter-propgraph-concurrently.out b/src/test/isolation/expected/alter-propgraph-concurrently.out
index a75e75b3ca3..5bc8c58e298 100644
--- a/src/test/isolation/expected/alter-propgraph-concurrently.out
+++ b/src/test/isolation/expected/alter-propgraph-concurrently.out
@@ -125,3 +125,69 @@ CREATE PROPERTY GRAPH public.pgg1
     )
 (1 row)
 
+
+starting permutation: s1b s1addp s2addp s1c s2pgdef
+step s1b: BEGIN;
+step s1addp: ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 ALTER LABEL pgl1 ADD PROPERTIES (a + b AS c);
+step s2addp: ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 ALTER LABEL pgl1 ADD PROPERTIES (a + b AS c); <waiting ...>
+step s1c: COMMIT;
+step s2addp: <... completed>
+ERROR:  property "c" already exists
+step s2pgdef: SELECT pg_get_propgraphdef('pgg1'::regclass);
+pg_get_propgraphdef                                                                                                                                  
+-----------------------------------------------------------------------------------------------------------------------------------------------------
+CREATE PROPERTY GRAPH public.pgg1
+    VERTEX TABLES (
+        pgt1 KEY (a) LABEL pgl1 PROPERTIES (b, (a + b) AS c) LABEL pgl2 PROPERTIES (a, b)
+    )
+(1 row)
+
+
+starting permutation: s1b s1addp s2addp s1r s2pgdef
+step s1b: BEGIN;
+step s1addp: ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 ALTER LABEL pgl1 ADD PROPERTIES (a + b AS c);
+step s2addp: ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 ALTER LABEL pgl1 ADD PROPERTIES (a + b AS c); <waiting ...>
+step s1r: ROLLBACK;
+step s2addp: <... completed>
+step s2pgdef: SELECT pg_get_propgraphdef('pgg1'::regclass);
+pg_get_propgraphdef                                                                                                                                  
+-----------------------------------------------------------------------------------------------------------------------------------------------------
+CREATE PROPERTY GRAPH public.pgg1
+    VERTEX TABLES (
+        pgt1 KEY (a) LABEL pgl1 PROPERTIES (b, (a + b) AS c) LABEL pgl2 PROPERTIES (a, b)
+    )
+(1 row)
+
+
+starting permutation: s1b s1alabel s2alabel s1c s2pgdef
+step s1b: BEGIN;
+step s1alabel: ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 ADD LABEL pgl3 PROPERTIES ALL COLUMNS;
+step s2alabel: ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 ADD LABEL pgl3 PROPERTIES ALL COLUMNS; <waiting ...>
+step s1c: COMMIT;
+step s2alabel: <... completed>
+ERROR:  label "pgl3" already exists
+step s2pgdef: SELECT pg_get_propgraphdef('pgg1'::regclass);
+pg_get_propgraphdef                                                                                                                                                 
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------
+CREATE PROPERTY GRAPH public.pgg1
+    VERTEX TABLES (
+        pgt1 KEY (a) LABEL pgl1 PROPERTIES (b) LABEL pgl2 PROPERTIES (a, b) LABEL pgl3 PROPERTIES (a, b)
+    )
+(1 row)
+
+
+starting permutation: s1b s1alabel s2alabel s1r s2pgdef
+step s1b: BEGIN;
+step s1alabel: ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 ADD LABEL pgl3 PROPERTIES ALL COLUMNS;
+step s2alabel: ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 ADD LABEL pgl3 PROPERTIES ALL COLUMNS; <waiting ...>
+step s1r: ROLLBACK;
+step s2alabel: <... completed>
+step s2pgdef: SELECT pg_get_propgraphdef('pgg1'::regclass);
+pg_get_propgraphdef                                                                                                                                                 
+--------------------------------------------------------------------------------------------------------------------------------------------------------------------
+CREATE PROPERTY GRAPH public.pgg1
+    VERTEX TABLES (
+        pgt1 KEY (a) LABEL pgl1 PROPERTIES (b) LABEL pgl2 PROPERTIES (a, b) LABEL pgl3 PROPERTIES (a, b)
+    )
+(1 row)
+
diff --git a/src/test/isolation/specs/alter-propgraph-concurrently.spec b/src/test/isolation/specs/alter-propgraph-concurrently.spec
index 50b7e0efe05..61f7de92fed 100644
--- a/src/test/isolation/specs/alter-propgraph-concurrently.spec
+++ b/src/test/isolation/specs/alter-propgraph-concurrently.spec
@@ -24,6 +24,8 @@ session s1
 step s1b	{ BEGIN; }
 step s1dlabel	{ ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 DROP LABEL pgl1; }
 step s1delem { ALTER PROPERTY GRAPH pgg1 DROP VERTEX TABLES (pgt1); }
+step s1addp { ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 ALTER LABEL pgl1 ADD PROPERTIES (a + b AS c); }
+step s1alabel { ALTER PROPERTY GRAPH pgg1 ALTER VERTEX TABLE pgt1 ADD LABEL pgl3 PROPERTIES ALL COLUMNS; }
 step s1c	{ COMMIT; }
 step s1r	{ ROLLBACK; }
 
@@ -56,3 +58,15 @@ permutation s1b s1delem s2addp s1c s2pgdef
 
 # s2addp succeeds since rollback leaves pgt1 in the graph
 permutation s1b s1delem s2addp s1r s2pgdef
+
+# s2addp fails since by then s1 has added the same property
+permutation s1b s1addp s2addp s1c s2pgdef
+
+# s2addp succeeds since rollback leaves pgl1 without the added property
+permutation s1b s1addp s2addp s1r s2pgdef
+
+# s2alabel fails since by then s1 has added the same label
+permutation s1b s1alabel s2alabel s1c s2pgdef
+
+# s2alabel succeeds since rollback leaves pgt1 without the added label
+permutation s1b s1alabel s2alabel s1r s2pgdef
diff --git a/src/test/regress/expected/create_property_graph.out b/src/test/regress/expected/create_property_graph.out
index f9960e5e0ae..5930d844319 100644
--- a/src/test/regress/expected/create_property_graph.out
+++ b/src/test/regress/expected/create_property_graph.out
@@ -200,6 +200,20 @@ CREATE PROPERTY GRAPH gx
     );
 DROP PROPERTY GRAPH gx;
 DROP TABLE t1x, t2x;
+CREATE PROPERTY GRAPH gx
+    VERTEX TABLES (
+        t1 KEY (a) LABEL l1 PROPERTIES (a AS p, a AS p)  -- duplicate property on label
+    );
+ERROR:  property "p" specified more than once
+ALTER PROPERTY GRAPH g4 ALTER VERTEX TABLE t2 ALTER LABEL t2 ADD PROPERTIES (k * 2 AS i_j);  -- duplicate property on label
+ERROR:  property "i_j" already exists
+CREATE PROPERTY GRAPH gx
+    VERTEX TABLES (
+        t1 KEY (a) LABEL l1 LABEL l1  -- duplicate label on element
+    );
+ERROR:  label "l1" already exists
+ALTER PROPERTY GRAPH g4 ALTER VERTEX TABLE t3 ADD LABEL t3l1 NO PROPERTIES;  -- duplicate label on element
+ERROR:  label "t3l1" already exists
 CREATE PROPERTY GRAPH gx
     VERTEX TABLES (
         t1 KEY (a) LABEL l1 PROPERTIES (a, a AS aa),
diff --git a/src/test/regress/sql/create_property_graph.sql b/src/test/regress/sql/create_property_graph.sql
index b10d7191506..a4285ef8846 100644
--- a/src/test/regress/sql/create_property_graph.sql
+++ b/src/test/regress/sql/create_property_graph.sql
@@ -155,6 +155,18 @@ CREATE PROPERTY GRAPH gx
 DROP PROPERTY GRAPH gx;
 DROP TABLE t1x, t2x;
 
+CREATE PROPERTY GRAPH gx
+    VERTEX TABLES (
+        t1 KEY (a) LABEL l1 PROPERTIES (a AS p, a AS p)  -- duplicate property on label
+    );
+ALTER PROPERTY GRAPH g4 ALTER VERTEX TABLE t2 ALTER LABEL t2 ADD PROPERTIES (k * 2 AS i_j);  -- duplicate property on label
+
+CREATE PROPERTY GRAPH gx
+    VERTEX TABLES (
+        t1 KEY (a) LABEL l1 LABEL l1  -- duplicate label on element
+    );
+ALTER PROPERTY GRAPH g4 ALTER VERTEX TABLE t3 ADD LABEL t3l1 NO PROPERTIES;  -- duplicate label on element
+
 CREATE PROPERTY GRAPH gx
     VERTEX TABLES (
         t1 KEY (a) LABEL l1 PROPERTIES (a, a AS aa),
-- 
2.34.1