Re: SKIP LOCKED DATA (work in progress)
| От | David Rowley |
|---|---|
| Тема | Re: SKIP LOCKED DATA (work in progress) |
| Дата | |
| Msg-id | CAApHDvp=9ZcnKp1BnBoFQsaJf7_0N3M1J9WY=+n-n97HwOeXOA@mail.gmail.com обсуждение исходный текст |
| Ответ на | Re: SKIP LOCKED DATA (work in progress) (Thomas Munro <munro@ip9.org>) |
| Ответы |
Re: SKIP LOCKED DATA (work in progress)
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| Список | pgsql-hackers |
On Sat, Aug 2, 2014 at 3:55 AM, Thomas Munro <munro@ip9.org> wrote:
On 1 August 2014 10:37, David Rowley <dgrowleyml@gmail.com> wrote:> Apart from this I can't see any other problems with the patch and I'd beThanks for all the guidance, I appreciate it! My review karma account
> very inclined, once the above are fixed up to mark the patch ready for
> commiter.
>
> Good work
is now well overdrawn.
Ok, then I have nothing more so it's time to pass this one along.
The only notes I can think to leave for the commiter would be around the precedence order of the lock policy, especially around a query such as:
SELECT * FROM (SELECT * FROM a FOR UPDATE SKIP LOCKED) a FOR UPDATE; -- skip locked wins
Of course the current behaviour is that NOWAIT wins over the standard FOR UPDATE, but with NOWAIT, there's only a chance of an error, there's no chance of giving incorrect results.
I checked what Oracle did in this situation and I see that they completely disallow FOR UPDATE inside of views and subqueries.
I could see an argument here that the outer most FOR UPDATE clause should be used, but I guess that ship has sailed when NOWAIT was added.
Marking as ready for commiter.
Regards
David Rowley
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