Re: Property graph: fix error handling when dropping non-existent label property

[Peter Eisentraut]

On 26.04.26 09:21, Chao Li wrote:

On Apr 24, 2026, at 20:38, Ashutosh Bapat <ashutosh.bapat....@gmail.com> wrote:

On Fri, Apr 24, 2026 at 1:03 PM Chao Li <li.evan.c...@gmail.com> wrote:

Hi,

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

Here is a simple repro:
```
evantest=# CREATE TABLE t1 (a int PRIMARY KEY, b int);
CREATE TABLE
evantest=#
evantest=# 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=#
evantest=# 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=# 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"
```

Thanks for the report. Agree that we need to provide a correct error
message. The code changes look good to me.

Cool! Thanks for reviewing and confirming.

This patch has been committed as part of

https://www.postgresql.org/message-id/CAExHW5teYi1Kyw2exqk8t%2BWF4wq0cUaWcWQo0oi7NpnmcctJHA%40mail.gmail.com

Thanks.