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

On 23 January 2013 17:15, Andres Freund <andres(at)2ndquadrant(dot)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

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Simon Riggs http://www.2ndQuadrant.com/
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