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().
