Re: Negative value of numGroups - Mailing list pgsql-bugs

From Andrey Lepikhov
Subject Re: Negative value of numGroups
Date
Msg-id 26c0c627-65a9-9e38-07f0-56861b75fc68@postgrespro.ru
Whole thread Raw
In response to Re: Negative value of numGroups  (Tom Lane <tgl@sss.pgh.pa.us>)
Responses Re: Negative value of numGroups
List pgsql-bugs
On 5/17/22 20:34, Tom Lane wrote:
> Andrey Lepikhov <a.lepikhov@postgrespro.ru> writes:
>> On 13/5/2022 11:56, Andrey Lepikhov wrote:
>>> (long) Min(numGroups, (double) LONG_MAX);
>>>
>>> can return negative value, if numGroups > LONG_MAX.
> 
> I see your point, but I don't think that repeating the same finicky
> and undocumented coding pattern in multiple places is a future-proof
> fix.  I'm inclined to think we should invent a function along the
> lines of "long clamp_double_to_long(double x)".  Given where it's
> used, maybe putting it beside clamp_row_est() would be good.
> 
>             regards, tom lane
Next version of the patch.
As I see, now we trying to use Cardinality type instead of double.
So, I named casting routine as clamp_cardinality_to_long.

-- 
Regards
Andrey Lepikhov
Postgres Professional
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