On 2015/02/11 4:06, Stephen Frost wrote:
> * Etsuro Fujita (fujita.etsuro@lab.ntt.co.jp) wrote:
>> On 2015/02/10 7:23, Dean Rasheed wrote:
>>> Sorry, I didn't have time to look at this properly. My initial thought
>>> is that expand_security_qual() needs to request a lock on rows coming
>> >from the relation it pushes down into a subquery if that relation was
>>> the result relation, because otherwise it won't have any locks, since
>>> preprocess_rowmarks() only adds PlanRowMarks to non-target relations.
>>
>> That seems close to what I had in mind; expand_security_qual() needs
>> to request a FOR UPDATE lock on rows coming from the relation it
>> pushes down into a subquery only when that relation is the result
>> relation and *foreign table*.
>
> I had been trying to work out an FDW-specific way to address this, but I
> think Dean's right that this should be addressed in
> expand_security_qual(), which means it'll apply to all cases and not
> just these FDW calls. I don't think that's actually an issue though and
> it'll match up to how SELECT FOR UPDATE is handled today.
Sorry, my explanation was not accurate, but I also agree with Dean's
idea. In the above, I just wanted to make it clear that such a lock
request done by expand_security_qual() should be limited to the case
where the relation that is a former result relation is a foreign table.
If it's OK, I'll submit a patch for that, maybe early next week.
Thank you for working on this issue!
Best regards,
Etsuro Fujita
