Re: [PATCH] random_normal function

> On Dec 14, 2022, at 9:17 PM, Michael Paquier <michael@paquier.xyz> wrote:
> 
> On Tue, Dec 13, 2022 at 03:51:11PM -0800, Paul Ramsey wrote:
>> Clearing up one CI failure.
> 
> +-- normal values converge on stddev == 2.0
> +SELECT round(stddev(random_normal(2, 2)))
> +  FROM generate_series(1, 10000);
> 
> I am not sure that it is a good idea to make a test based on a random
> behavior that should tend to a normalized value.  This is costly in
> cycles, requiring a lot of work just for generate_series().  You could
> do the same kind of thing as random() a few lines above?
> 
> +SELECT bool_and(random_string(16) != random_string(16)) AS same
> +  FROM generate_series(1,8);
> That should be fine in terms of impossible chances :)
> 
> +       ereport(ERROR,
> +           (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
> +            errmsg("return size must be non-negative")))
> This could have a test, same for 0.
> 
> +#ifndef M_PI
> +#define M_PI 3.14159265358979323846
> +#endif
> Postgres' float.h includes one version of that.

Thanks again!

P