Unnest array by one level

Question

I want to take an array of n dimensions and return set containing rows of arrays of n-1 dimensions. For example, take the array ARRAY[[1,2,3]

Answer 1

A word of caution: when using array_agg on postgres <9 order may change PostgreSQL array_agg order If you plan to use the unnested array say for finding argmax, this will corrupt your data.