13cd97e6c8
The array <@ and @> operators do not worry about duplicates: if every member of array X matches some element of array Y, then X is contained in Y, even if several members of X get matched to the same Y member. This was not explicitly stated in the docs though, so improve matters. Discussion: https://postgr.es/m/156614120484.1310.310161642239149585@wrigleys.postgresql.org