Re: [COMMITTERS] pgsql: Improve concurrency of foreign key locking

On 01/23/2013 12:48 PM, Simon Riggs wrote:
> On 23 January 2013 17:15, Andres Freund <andres@2ndquadrant.com> wrote:
>> On 2013-01-23 11:58:28 -0500, Andrew Dunstan wrote:
>>> On 01/23/2013 10:12 AM, Alvaro Herrera wrote:
>>>> Improve concurrency of foreign key locking
>>> This error message change looks rather odd, and has my head spinning a bit:
>>>
>>> -                    errmsg("SELECT FOR UPDATE/SHARE cannot be applied to
>>> the nullable side of an outer join")));
>>> +                    errmsg("SELECT FOR UPDATE/SHARE/KEY UPDATE/KEY SHARE
>>> cannot be applied to the nullable side of an outer join")))
>>>
>>> Can't we do better than that?
>> I don't really see how? I don't think listing only the current locklevel
>> really is an improvement and something like "SELECT ... FOR $locktype
>> cannot .." seem uncommon enough in pg error messages to be strange.
>> Now I aggree that listing all those locklevels isn't that nice, but I
>> don't really have a better idea.
> "row level locks cannot be applied to the NULLable side of an outer join"
> Hint: there are no rows to lock
>

Yeah, this is really more informative than either, I think.

cheers

andrew