Re: BUG #17847: Unaligned memory access in ltree_gist

Hi!

On Tue, Apr 18, 2023 at 6:25 PM Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Pavel Borisov <pashkin.elfe@gmail.com> writes:
> > On Tue, 18 Apr 2023 at 19:06, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> >> The DETAIL message's grammar seems a bit off.  Also, this is confusing the
> >> range limitation with the alignment requirement.  How about just saying
> >> ERROR:  siglen value must be a multiple of 4

This  message is changed as you proposed.

> > I definitely like this wording.
>
> >> and leaving out-of-range cases to be handled by the existing check?
>
> > But that means that if we try 2025 then we just get it is not multiple
> > of 4 (and no clue of the range). Then we try 2028 and get another
> > error that it's outside of range. I suppose giving clues one by one
> > makes this look like a step-by-step quest. But in principle it's
> > possible.
>
> Well, that's the case just about everywhere else that there are multiple
> constraints on an input.  It'd be impossibly unwieldy, and confusing,
> for every error message to include details on all the other errors
> you might have hit if you didn't hit that one.
>
> FWIW, I find it odd that the multiple-of-4 error comes out in advance
> of the range check; that seems backwards somehow.  Maybe we should
> alter the order of applying the range check and the custom validator?

I think it was intended that custom validators work after builtin
validation, but the current order of validation is caused by bug.  I
don't see why build_local_reloptions() should call custom validators
when validate == false.  Patch 0001 fixes this.  I propose to
backpatch this.

------
Regards,
Alexander Korotkov