Re: [PATCH] Improve geometric types - Mailing list pgsql-hackers

On 08/09/2018 11:42 AM, Kyotaro HORIGUCHI wrote:
> At Wed, 8 Aug 2018 14:39:54 +0200, Tomas Vondra <tomas.vondra@2ndquadrant.com> wrote in
<6ecb4f61-1fb1-08a1-31d6-e58e9c352374@2ndquadrant.com>
>>
>>
>> On 08/03/2018 02:39 PM, Tomas Vondra wrote:
>>> On 08/03/2018 06:40 AM, Kyotaro HORIGUCHI wrote:
>>>> ...
>>>>
>>>> I'm not confident on replacing double to float8 partially in gist
>>>> code. After the 0002 patch applied, I see most of problematic
>>>> usage of double or bare arithmetic on dimentional values in
>>>> gistproc.c.
>>>>
>>>>> static inline float
>>>>> non_negative(float val)
>>>>> {
>>>>>     if (val >= 0.0f)
>>>>>         return val;
>>>>>     else
>>>>>         return 0.0f;
>>>>> }
>>>>
>>>> It is used as "non_negative(overlap)", where overlap is float4,
>>>> which is calculated using float8_mi.  Float4 makes sense only if
>>>> we need to store a large number of it to somewhere but they are
>>>> just working varialbles. Couldn't we eliminate float4 that
>>>> doesn't have a requirement to do so?
>>>>
>>> I'm not sure I follow. The patch does not modify non_negative() at
>>> all, and we still call it like this:
>>>      if (non_negative(overlap) < non_negative(context->overlap) ||
>>>          (range > context->range &&
>>>           non_negative(overlap) <= non_negative(context->overlap)))
>>>          selectthis = true;
>>> where all the "overlap" values are still float4. The only thing that
>>> changed here is that instead of doing the arithmetic operations
>>> directly we call float8_mi/float8_div to benefit from the float8
>>> handling.
>>> So I'm not sure how does the patch beaks this? And what do you mean by
>>> 'eliminate float4'?
>>>
>>
>> Kyotaro-san, can you explain what your concerns regarding this bit
>> are? I'd like to get 0002 committed, but I'm not sure I understand
>> your point about the changes in gist code, so I can't address
>> them. And I certainly don't want to just ignore them ...
> 
> It doesn't break nothing so nothing must be done with this. Just
> I was a bit uneasy to see meaninglessly used foat4. Sorry for
> the unnecessary argument.
> 
> After all I don't object to commit it in this shape.
> 

Understood. Thanks for the explanation.

I've pushed parts 0001 and 0002, as submitted on August 1. Let's see if
that upsets some of the buildfarm animals.


regards

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