Re: [PATCH] random_normal function

From: Paul Ramsey <pramsey(at)cleverelephant(dot)ca>
To: Michael Paquier <michael(at)paquier(dot)xyz>
Cc: Pgsql Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: [PATCH] random_normal function
Date: 2022-12-09 23:20:35
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> On Dec 9, 2022, at 9:17 AM, Paul Ramsey <pramsey(at)cleverelephant(dot)ca> wrote:
>> On Dec 8, 2022, at 8:29 PM, Michael Paquier <michael(at)paquier(dot)xyz> wrote:
>> On Thu, Dec 08, 2022 at 04:44:56PM -0800, Paul Ramsey wrote:
>>> Final tme, with fixes from cirrusci.
>> Well, why not. Seems like you would use that a lot with PostGIS.
>> #include <math.h> /* for ldexp() */
>> +#include <float.h> /* for DBL_EPSILON */
>> And be careful with the order here.
> Should be ... alphabetical?
>> +static void
>> +drandom_check_default_seed()
>> We always use (void) rather than empty parenthesis sets.
> OK
>> I would not leave that unchecked, so I think that you should add
>> something in ramdom.sql. Or would you prefer switching some of
>> the regression tests be switched so as they use the new normal
>> function?
> Reading through those tests... seems like they will (rarely) fail. Is that... OK?
> The tests seem to be mostly worried that random() starts returning constants, which seems like a good thing to test for (is the random number generating returning randomness).
> An obvious test for this function is that the mean and stddev converge on the supplied parameters, given enough inputs, which is actually kind of the opposite test. I use the same random number generator as the uniform distribution, so that aspect is already covered by the existing tests.
>> (Ahem. Bonus points for a random_string() returning a bytea, based on
>> pg_strong_random().)
> Would love to. Separate patch of bundled into this one?

Here's the original with suggestions applied and a random_string that applies on top of it.



Attachment Content-Type Size
random_normal_05a.patch application/octet-stream 7.4 KB
random_normal_05b.patch application/octet-stream 3.4 KB

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