Horton

Re: [PATCH] random_normal function

Paul Ramsey <pramsey@cleverelephant.ca>

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From: Paul Ramsey <pramsey@cleverelephant.ca>
To: Michael Paquier <michael@paquier.xyz>
Cc: Pgsql Hackers <pgsql-hackers@postgresql.org>
Date: 2022-12-09T23:20:35Z
Lists: pgsql-hackers

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Round off random_normal() test results one more decimal place.

  2. Remove pg_regress' never-documented "ignore" feature.

  3. Upgrade the random.sql regression test.

  4. Invent random_normal() to provide normally-distributed random numbers.

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> 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, 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.

Thanks!

P