Robert Haas <robertmh...@gmail.com> writes: > On Tue, Jul 19, 2022 at 9:53 AM Andrew Dunstan <and...@dunslane.net> wrote: >> Why not have an optional second parameter for array_shuffle that >> indicates whether or not to flatten? e.g. array_shuffle(my_array, >> flatten => true)
> IMHO, if we think that's something many people are going to want, it > would be better to add an array_flatten() function, because that could > be used for a variety of purposes, whereas an option to this function > can only be used for this function. Agreed. Whether it's really needed, I dunno --- I don't recall the issue having come up before. After taking a second look through https://www.postgresql.org/docs/current/functions-array.html it seems like the things that treat arrays as flat even when they are multi-D are just * unnest(), which is more or less forced into that position by our type system: it has to be anyarray returning anyelement, not anyarray returning anyelement-or-anyarray-depending. * array_to_string(), which maybe could have done it differently but can reasonably be considered a variant of unnest(). * The containment/overlap operators, which are kind of their own thing anyway. Arguably they got this wrong, though I suppose it's too late to rethink that. Everything else either explicitly rejects more-than-one-D arrays or does something that is compatible with thinking of them as arrays-of-arrays. So I withdraw my original position. These functions should just shuffle or select in the array's first dimension, preserving subarrays. Or else be lazy and reject more-than-one-D arrays; but it's probably not that hard to handle them. regards, tom lane
