Re: [PATCH] Introduce array_shuffle() and array_sample()

Am 18.07.22 um 23:48 schrieb Martin Kalcher:
>
> If we go with (1) array_shuffle() and array_sample() should shuffle each
> element individually and always return a one-dimensional array.
>
>   select array_shuffle('{{1,2},{3,4},{5,6}}');
>   -----------
>    {1,4,3,5,6,2}
>
>   select array_sample('{{1,2},{3,4},{5,6}}', 3);
>   ----------
>    {1,4,3}
>
> If we go with (2) both functions should only operate on the first
> dimension and shuffle whole subarrays and keep the dimensions intact.
>
>   select array_shuffle('{{1,2},{3,4},{5,6}}');
>   ---------------------
>    {{3,4},{1,2},{5,6}}
>
>   select array_sample('{{1,2},{3,4},{5,6}}', 2);
>   ---------------
>    {{3,4},{1,2}}
>

Having thought about it, i would go with (2). It gives the user the
ability to decide wether or not array-of-arrays behavior is desired. If
he wants the behavior of (1) he can flatten the array before applying
array_shuffle(). Unfortunately there is no array_flatten() function (at
the moment) and the user would have to work around it with unnest() and
array_agg().