Re: [PATCH] random_normal function - Mailing list pgsql-hackers

From Paul Ramsey
Subject Re: [PATCH] random_normal function
Date
Msg-id 0FC87A09-8CAD-4FB6-B675-3432D8F6C6A3@cleverelephant.ca
Whole thread Raw
In response to Re: [PATCH] random_normal function  (Paul Ramsey <pramsey@cleverelephant.ca>)
Responses Re: [PATCH] random_normal function  (Paul Ramsey <pramsey@cleverelephant.ca>)
List pgsql-hackers

> On Dec 9, 2022, at 9:17 AM, Paul Ramsey <pramsey@cleverelephant.ca> wrote:
>
>
>> On Dec 8, 2022, at 8:29 PM, Michael Paquier <michael@paquier.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,
sothat 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.

Thanks!

P

Attachment

pgsql-hackers by date:

Previous
From: Corey Huinker
Date:
Subject: Re: Error-safe user functions
Next
From: Michael Paquier
Date:
Subject: Re: Raising the SCRAM iteration count