From: Chao Li <li.evan.chao@gmail.com>
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Subject: Property graph: fix error handling when dropping non-existent label
 property
Message-Id: <1DA5D52A-4AFA-426E-83F7-42ED974D682B@gmail.com>
Date: Fri, 24 Apr 2026 15:32:38 +0800
To: PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Archived-At: 
 <https://www.postgresql.org/message-id/1DA5D52A-4AFA-426E-83F7-42ED974D682B%40gmail.com>
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Hi,

I am testing graph tables today and noticed an improper error message =
when dropping a property.

Here is a simple repro:
```
evantest=3D# CREATE TABLE t1 (a int PRIMARY KEY, b int);
CREATE TABLE
evantest=3D#
evantest=3D# CREATE PROPERTY GRAPH g
evantest-#     VERTEX TABLES (
evantest(#         t1
evantest(#             LABEL l1 PROPERTIES (a AS p1)
evantest(#             LABEL l2 PROPERTIES (b AS p2)
evantest(#     );
CREATE PROPERTY GRAPH
evantest=3D#
evantest=3D# ALTER PROPERTY GRAPH g
evantest-#     ALTER VERTEX TABLE t1
evantest-#     ALTER LABEL l1 DROP PROPERTIES (p2);
ERROR:  could not find tuple for label property 0
```

This does not look like a normal user-facing SQL error message.

Looking into the code, AlterPropGraph() checks whether the property =
exists in the graph, but does not check if label property exists. As a =
result, InvalidOid can be passed to ObjectAddressSet() and then to =
performDeletion().

The fix is simple, just check the label-property OID before trying to =
delete it. I also added a regress test.

With the patch, the error becomes:
```
evantest=3D# ALTER PROPERTY GRAPH g
evantest-#     ALTER VERTEX TABLE t1
evantest-#     ALTER LABEL l1 DROP PROPERTIES (p2);
ERROR:  property graph "g" element "t1" label "l1" has no property "p2"
```

Best regards,
--
Chao Li (Evan)
HighGo Software Co., Ltd.
https://www.highgo.com/


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	filename=v1-0001-Fix-DROP-PROPERTIES-check-for-property-graph-labe.patch
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