Re: BUG #17798: Incorrect memory access occurs when using BEFORE ROW UPDATE trigger

Hello Richard,

19.04.2023 11:29, Richard Guo wrote:
> I have a second look at this issue and now I think the fix in v1 patch
> is correct.  I think the comment needs to be updated for this change,
> maybe something like
>
>   * (Typically, newslot was also generated by ExecGetUpdateNewTuple, so
>   * that epqslot_clean will be that same slot and the copy step below
> - * is not needed.)
> + * is not needed.  And we need to materialize newslot in this case,
> + * since its tuple might be dependent on oldslot's storage, which
> + * might not be a local copy and be freed before we fetch newslot's
> + * tuple.)

Thanks for looking into this!

I've updated the comment based on your suggestion. Please look at the patch
attached.

I hesitate to add the isolation test to the patch as adding a dedicated
test just for this case seems too wasteful to me. Maybe that scenario could
be added to one of the existing trigger-related tests, but I couldn't find a
test, which is generic enough for that.

Best regards,
Alexander