Re: Update on true serializable techniques in MVCC

On 18.12.09 16:42 , Florian Weimer wrote:
> * Florian Pflug:
>> On 16.12.09 16:40 , Kevin Grittner wrote:
>>> Nicolas Barbier<nicolas(dot)barbier(at)gmail(dot)com> wrote:
>>>
>>>> I am not sure whether the serialization failures that it may cause
>>>> are dependent on the plan used.
>>>
>>> They are.
>>
>> But so are failures due to deadlocks even today, no?
>
> They are detected. In this context, "serialization failure" means
> that PostgreSQL generates a history which lacks one-copy
> serializability, without reporting any errors.

No, the whole point of this SIREAD-lock technique is to prevent that
once and for all, and make SERIALIZABLE transaction really serializable
(or fail with a "serialization error").

> (In the general case,
> the unique constraint violation which bugs me personally is a
> different beast and does result in an error.)
I'm not sure I understand what you are referring to here.

best regards,
Florian Pflug