Re: Avoid orphaned objects dependencies, take 3

Hi Bertrand,

24.04.2024 11:38, Bertrand Drouvot wrote:
>> Please find attached v2 that should not produce the issue anymore (I launched a
>> lot of attempts without any issues). v1 was not strong enough as it was not
>> always checking for the dependent object existence. v2 now always checks if the
>> object still exists after the additional lock acquisition attempt while recording
>> the dependency.
>>
>> I still need to think about v2 but in the meantime could you please also give
>> v2 a try on you side?
> I gave more thought to v2 and the approach seems reasonable to me. Basically what
> it does is that in case the object is already dropped before we take the new lock
> (while recording the dependency) then the error message is a "generic" one (means
> it does not provide the description of the "already" dropped object). I think it
> makes sense to write the patch that way by abandoning the patch's ambition to
> tell the description of the dropped object in all the cases.
>
> Of course, I would be happy to hear others thought about it.
>
> Please find v3 attached (which is v2 with more comments).

Thank you for the improved version!

I can confirm that it fixes that case.
I've also tested other cases that fail on master (most of them also fail
with v1), please try/look at the attached script. (There could be other
broken-dependency cases, of course, but I think I've covered all the
representative ones.)

All tested cases work correctly with v3 applied — I couldn't get broken
dependencies, though concurrent create/drop operations can still produce
the "cache lookup failed" error, which is probably okay, except that it is
an INTERNAL_ERROR, which assumed to be not easily triggered by users.

Best regards,
Alexander