Re: integer square root function proposed

On 12/17/22 19:39, Martin L. Buchanan wrote:
> Dear PostgreSQL colleagues:
>
> I have just joined this, my first PG mailing list.
>
> Reading the documentation I found no built-in function for integer
> square root, requiring a sequence of:
>
> floor(sqrt(foo))::integer
>
> to go from an integer to the integer square root as an integer.
>
> If PG leaders smile on this suggestion, could we have *isqrt*(foo)
> where foo has a numeric type and the result type is the same numeric
> type, with the result type being the integer square root for foo >= 0
> and producing an error if negative? (And with infinities and NaNs
> processed as described in 8.1 Numeric Types).
>
> I did not see an explicit enhancement request list in the PG mailing
> lists. Recommendations for a more specific list to post this to are
> welcome.
>
>

I suspect the majority are comfortable getting a non-integer result for
the square root of a number.  What environment have you which needs
(sqrt(a) * sqrt(a)) < a-epsilon?