Обсуждение: Re: [COMMITTERS] pgsql: Improve concurrency of foreign key locking
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?
(It's also broken my FDW check, but I'll fix that when this is sorted out)
cheers
andrew
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.
Andres
-- Andres Freund http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training &
Services
Andres Freund <andres@2ndquadrant.com> writes:
> On 2013-01-23 11:58:28 -0500, Andrew Dunstan wrote:
>> 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.
I don't really see what's wrong with the original spelling of the
message. The fact that you can now insert KEY in there doesn't really
affect anything for the purposes of this error.
regards, tom lane
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
-- Simon Riggs http://www.2ndQuadrant.com/PostgreSQL Development, 24x7 Support, Training & Services
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?
Basically this message says "a SELECT with a locking clause attached
cannot be blah blah". There are many messages that had the original
code saying "SELECT FOR UPDATE cannot be blah blah", which was later
(8.1) updated to say "SELECT FOR UPDATE/SHARE cannot be blah blah". I
expanded them using the same logic, but maybe there's a better
suggestion? Note that the SELECT reference page now has a subsection
called "The locking clause", so maybe it's okay to use that term now.
--
Álvaro Herrera http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services
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
Simon Riggs <simon@2ndQuadrant.com> writes:
> On 23 January 2013 17:15, Andres Freund <andres@2ndquadrant.com> wrote:
>> On 2013-01-23 11:58:28 -0500, Andrew Dunstan wrote:
>>> Can't we do better than that?
> "row level locks cannot be applied to the NULLable side of an outer join"
I think it should read "row-level locks cannot ...", but otherwise this
is a fine idea.
> Hint: there are no rows to lock
This bit doesn't seem to be either accurate or helpful, though.
regards, tom lane
Tom Lane wrote: > Simon Riggs <simon@2ndQuadrant.com> writes: > > On 23 January 2013 17:15, Andres Freund <andres@2ndquadrant.com> wrote: > >> On 2013-01-23 11:58:28 -0500, Andrew Dunstan wrote: > >>> Can't we do better than that? > > > "row level locks cannot be applied to the NULLable side of an outer join" > > I think it should read "row-level locks cannot ...", but otherwise this > is a fine idea. Thanks for the suggestion, I have changed all these messages. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services