Re: minor fix for acquire_inherited_sample_rows

On Mon, Apr 23, 2018 at 8:46 PM, Alvaro Herrera <alvherre(at)alvh(dot)no-ip(dot)org> wrote:
> Hello Amit
>
> Amit Langote wrote:
>
>> acquire_inherited_sample_rows() currently uses equalTupleDescs() being
>> false as the condition for going to tupconv.c to determine whether tuple
>> conversion is needed. But equalTupleDescs() will always return false if
>> it's passed TupleDesc's of two different tables, which is the most common
>> case here. So I first thought we should just unconditionally go to
>> tupconv.c, but there is still one case where we don't need to, which is
>> the case where the child table is same as the parent table. However, it
>> would be much cheaper to just check if the relation OIDs are different
>> instead of calling equalTupleDescs, which the attached patch teaches it to do.
>
> When (not if) we get around to updating equalTupleDescs to cope, we will
> need this call right where it is (and we'd have a hard time finding this
> potential callsite later, I think). If this were a hot spot I would be
> happy to change it, but it's not so I'd rather leave it alone.
>
+1

--
Best Wishes,
Ashutosh Bapat
EnterpriseDB Corporation
The Postgres Database Company