Re: [PATCH] Fix division by zero (explain.c)

On Sat, May 09, 2020 at 02:51:50PM -0300, Ranier Vilela wrote:
>Em sáb., 9 de mai. de 2020 às 14:44, Tomas Vondra <
>tomas(dot)vondra(at)2ndquadrant(dot)com> escreveu:
>
>> On Sat, May 09, 2020 at 06:48:59AM -0300, Ranier Vilela wrote:
>> >Em sáb., 9 de mai. de 2020 às 01:45, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
>> escreveu:
>> >
>> >> James Coleman <jtc331(at)gmail(dot)com> writes:
>> >> > There are always full sort groups before any prefix groups can happen,
>> >> > so we know (even though the tooling doesn't) that the 2nd test can
>> >> > never contradict the first.
>> >>
>> >> So maybe an assertion enforcing that would be appropriate?
>> >> Untested, but:
>> >>
>> >> - if (fullsortGroupInfo->groupCount == 0 &&
>> >> - prefixsortGroupInfo->groupCount == 0)
>> >> + if (fullsortGroupInfo->groupCount == 0)
>> >> + {
>> >> + Assert(prefixsortGroupInfo->groupCount
>> ==
>> >> 0);
>> >> continue;
>> >> + }
>> >>
>> >I agree, asserts always help.
>> >
>>
>> That doesn't work, because the prefixSortGroupInfo is used before
>> assignment, producing compile-time warnings.
>>
>> I've pushed a simpler fix without the assert. If we want to make this
>> check, perhaps doing it in incremental sort itself would be better than
>> doing it in explain.
>>
>Thanks anyway for the commit.
>But if you used the first version of my patch, would the author be me and
>am I as reported?
>What does it take to be considered the author?
>

Apologies. I should have listed you as an author, not just in the
reported-by field.

regards

--
Tomas Vondra http://www.2ndQuadrant.com
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