Re: Race and Locking? was Re: Duplicate rows with same key in DB?

Also - get_or_create doesn't always prevent a race condition if you have high traffic.. depending on your code+stack.

I already did a post about this a while back:

http://markmail.org/message/j3qr2y26i5uk7c3z 

On Sat, Jun 23, 2012 at 8:57 AM, Melvyn Sopacua <m.r.sopacua@gmail.com> wrote:

On 23-6-2012 9:52, Melvyn Sopacua wrote:
> On 23-6-2012 0:02, ydjango wrote:
>>
>> Thank you, I also believe it is Race condition. I do not want to use
>> get_or_create as I like to have control over DB writes and updates. I will
>> try Unique_together and catch the integrity error exception as Kurtis
>> suggested or check again before doing save().
>>
>> or just thinking aloud, Is there a way to acquire a lock which can
>> serialize any other requests which have same "a" and "b" values?
>
> unique_together + transaction middleware.
> https://docs.djangoproject.com/en/1.4/topics/db/transactions/

Ok, hit send too soon. No, this doesn't give you access to other
requests as far as I can tell, but operations depending upon the insert
operation succeeding are now part of a transaction and can be handled
more gracefully inside django as well, pending the result of the
transaction.

--
Melvyn Sopacua


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