Re: [HACKERS] Restrict concurrent update/delete with UPDATE of partition key

On 2018-04-04 22:10:06 -0700, David G. Johnston wrote:
> On Wednesday, April 4, 2018, Amit Kapila <amit(dot)kapila16(at)gmail(dot)com> wrote:
>
> > On Thu, Apr 5, 2018 at 7:14 AM, Andres Freund <andres(at)anarazel(dot)de> wrote:
> > >
> >
> > > Questions:
> > >
> > > - I'm not perfectly happy with
> > > "tuple to be locked was already moved to another partition due to
> > concurrent update"
> > > as the error message. If somebody has a better suggestions.
> > >
> >
> > I don't have any better suggestion, but I have noticed a small
> > inconsistency in the message. In case of delete, the message is
> > "tuple to be updated was ...". I think here it should be "tuple to be
> > deleted was ..."
> >
>
> The whole "moved to another partition" explains why and seems better placed
> in the errdetail. The error itself should indicate which attempted action
> failed. And the attempted action for the end user usually isn't the scope
> of "locked tuple" - it's the insert or update, the locking is a side effect
> (why).

Well, update/delete have their own messages, don't think you can get
this for inserts (there'd be no tuple to follow across EPQ). The case I
copied from above, was locking a tuple, hence the reference to that.

I don't agree with moving "moved to another partition" to errdetail,
that's *the* crucial detail. If there's anything in the error message,
it should be that.

Greetings,

Andres Freund