Re: fix possible optimizations in ATExecAttachPartition()

On 2017/06/13 18:08, Jeevan Ladhe wrote:
> Hi,
>
> I was doing some testing for my default partitioning work, and I realized
> that
> there seem to be a some optimization possible (and I think we should really
> have
> this optimization) for logic around handling the "key IS NOT NULL"
> constraints
> followed by predicate_implied_by() call.
>
> 1. Consider, if predicate_implied_by() returns false, in that case
> skip_validate
> is left set to false, and we really do not want to do lots of stuff followed
> this decision just to prove that the scan cannot be avoided(which is already
> decided in this case) if there is no NOT NULL constraint on the partition
> key
> column.
>
> 2. Further, if we have already decided not to skip the scan, we should
> really have
> a break in following if block:
>
> if (!partition_accepts_null &&
> (partattno == 0 ||
> !bms_is_member(partattno, not_null_attrs)))
> skip_validate = false;
>
>
> I have made above changes in the attached patch.
> PFA, and let me know if I am missing something here.

Yeah, I was thinking the same while writing the patch posted on the thread
"A bug in mapping attributes in ATExecAttachPartition()" [1]. That patch
adds the break you mention in 2, but didn't do anything about point 1.

In any case, +1 to your patch. I'll rebase if someone decides to commit
it first.

Thanks,
Amit

[1]
https://www.postgresql.org/message-id/a5df1cf6-dc51-1720-2abe-7957502b2cf9%40lab.ntt.co.jp