> On 29 Sep 2022, at 21:33, Tom Lane <t...@sss.pgh.pa.us> wrote: > > Martin Kalcher <martin.kalc...@aboutsource.net> writes: >> New patch: array_shuffle() and array_sample() use pg_global_prng_state now. > > I took a closer look at the patch today.
Since this seems pretty close to going in, and seems like quite useful
functions, I took a look to see if I could get it across the line (although I
noticed that CFM beat me to the clock in sending this =)).
> I find this behavior a bit surprising:
>
> +SELECT
> array_dims(array_sample('[-1:2][2:3]={{1,2},{3,NULL},{5,6},{7,8}}'::int[],
> 3));
> + array_dims
> +-------------
> + [-1:1][2:3]
> +(1 row)
>
> I can buy preserving the lower bound in array_shuffle(), but
> array_sample() is not preserving the first-dimension indexes of
> the array, so ISTM it ought to reset the first lower bound to 1.
I might be daft but I'm not sure I follow why not preserving here, can you
explain?
The rest of your comments have been addressed in the attached v6 I think
(although I'm pretty sure the docs part is just as bad now, explaining these in
concise words is hard, will take another look with fresh eyes tomorrow).
--
Daniel Gustafsson
v6-0001-Introduce-array_shuffle-and-array_sample.patch
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