Re: SKIP LOCKED DATA (work in progress)

On 31 August 2014 01:36, Thomas Munro <munro(at)ip9(dot)org> wrote:
> On 28 August 2014 00:25, Alvaro Herrera <alvherre(at)2ndquadrant(dot)com> wrote:
>> Thomas Munro wrote:
>>> I haven't yet figured out how to get get into a situation where
>>> heap_lock_updated_tuple_rec waits.
>>
>> Well, as I think I said in the first post I mentioned this, maybe there
>> is no such situation. In any case, like the EvalPlanQualFetch issue, we
>> can fix it later if we find it.
>
> I finally came up with a NOWAIT spec that reaches
> heap_lock_updated_rec and then blocks. I can't explain why exactly...
> but please see attached. The fix seems fairly straightforward. Do
> you think I should submit an independent patch to fix this case (well
> there are really two cases, since there is a separate multixact path)
> for the existing NOWAIT support and then tackle the SKIP LOCKED
> equivalent separately?

Oops, that isolation wasn't right, please disregard. Unless you think
this obscure case needs to be addressed before the SKIP LOCKED patch
can be committed, I will investigate it separately and maybe submit
something to a future commitfest.

Best regards,
Thomas Munro