Thread

Re: [Bug][patch]: After dropping the last label from a property graph element, invoking pg_get_propgraphdef() triggers an assertion failure

Ashutosh Bapat <ashutosh.bapat.oss@gmail.com> — 2026-05-12T07:01:03Z

On Tue, May 12, 2026 at 7:05 AM Ashutosh Bapat
<ashutosh.bapat.oss@gmail.com> wrote:
>
> On Mon, May 4, 2026 at 8:16 PM Peter Eisentraut <peter@eisentraut.org> wrote:
> >
> > On 28.04.26 17:02, Ashutosh Bapat wrote:
> > > We are looking up element label catalogs twice in this patch - first
> > > to find the label to be dropped and then to find the number of labels
> > > associated with the given element. I combined these two into a single
> > > while loop.
> >
> > That looks okay, but I think the names of the local variables are now a
> > bit off.  I would expect elrel and elscan to refer to
> > pg_propgraph_element, not pg_propgraph_element_label.  Maybe use
> > ellabelrel etc.
>
> Done.
>
> >
> > Also, I think this code needs to think a bit about locking to handle the
> > situation where more than one DROP LABEL operation happens concurrently.
> >
>
> AlterPropGraph already takes ShareRowExclusiveLock at the beginning so
> only one label can be dropped at a time. I have added an isolation
> test to test the scenario. We could further add some more tests to
> make sure that properties can not be added to a label being dropped,
> adding label to an element being dropped, adding label to an element
> being added etc. Would that be an overkill?

Here's the patchset without the extra tests.

-- 
Best Wishes,
Ashutosh Bapat