Re: Possible copy and past error? (\usr\backend\commands\analyze.c)

On Sat, Mar 28, 2020 at 11:49 AM Ranier Vilela <ranier.vf@gmail.com> wrote:
>
> Em sex., 27 de mar. de 2020 às 20:49, Tom Lane <tgl@sss.pgh.pa.us> escreveu:
>>
>> Ranier Vilela <ranier.vf@gmail.com> writes:
>> > Can someone check if there is a copy and paste error, at file:
>> > \usr\backend\commands\analyze.c, at lines 2225 and 2226?
>> > int num_mcv = stats->attr->attstattarget;
>> > int num_bins = stats->attr->attstattarget;
>>
>> No, that's intentional I believe.  Those are independent variables
>> that just happen to start out with the same value.
>
> Neither you nor I can say with 100% certainty that the original author's intention.

Given that Tom is the original author, I think it's a lot more likely
that he knows what the original authors intention was. It's certainly
been a few years, so it probably isn't 100%, but the likelihood is
pretty good.


>> > To silence this alert.
>>
>> If you have a tool that complains about that coding, I think the
>> tool needs a solid whack upside the head.  There's nothing wrong
>> with the code, and it clearly expresses the intent, which the other
>> way doesn't.  (Or in other words: it's the compiler's job to
>> optimize away the duplicate fetch.  Not the programmer's.)
>
> I completely disagree. My tools have proven their worth, including finding serious errors in the code, which
fortunatelyhave been fixed by other committers. 
> When issuing this alert, the tool does not value judgment regarding performance or optimization, but it does an
excellentjob of finding similar patterns in adjacent lines, and the only thing it asked for was to be asked if this was
reallythe case. original author's intention. 

All tools will give false positives. This simply seems one of those --
it certainly could have been indicating a problem, but in this case it
didn't.

--
 Magnus Hagander
 Me: https://www.hagander.net/
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