Re: [HACKERS] Tuple-routing for certain partitioned tables notworking as expected

On 2017/08/29 20:18, Etsuro Fujita wrote:
> On 2017/08/25 22:26, Robert Haas wrote:
>> On Wed, Aug 23, 2017 at 4:55 AM, Etsuro Fujita
>> <fujita.etsuro@lab.ntt.co.jp> wrote:
>>> Agreed, but I'd vote for fixing this in v10 as proposed; I agree that just
>>> ripping the CheckValidResultRel checks out entirely is not a good idea,
>>> but
>>> that seems OK to me at least as a fix just for v10.
>>
>> I'm still not on-board with having this be the one case where we don't
>> do CheckValidResultRel.  If we want to still call it but pass down
>> some additional information that can selectively skip certain checks,
>> I could probably live with that.
> 
> Another idea would be to not do CheckValidResultRel for partitions in
> ExecSetupPartitionTupleRouting; instead, do that the first time the
> partition is chosen by ExecFindPartition, and if successfully checked,
> initialize the partition's ResultRelInfo and other stuff.  (We could skip
> this after the first time by checking whether we already have a valid
> ResultRelInfo for the chosen partition.)  That could allow us to not only
> call CheckValidResultRel the way it is, but avoid initializing useless
> partitions for which tuples aren't routed at all.

I too have thought about the idea of lazy initialization of the partition
ResultRelInfos.  I think it would be a good idea, but definitely something
for PG 11.

Thanks,
Amit