Re: Subtract one array from another, both with non-unique elements - Mailing list pgsql-general

CREATE OR REPLACE FUNCTION arrexcept(anyarray, anyarray) RETURNS anyarray AS $arrexcept$

  SELECT array_agg(un) FROM (

    SELECT un, row_number() OVER (PARTITION BY un ORDER BY ord) id FROM unnest($1) with ordinality AS t(un, ord)

    EXCEPT

    SELECT un, row_number() OVER (PARTITION BY un ORDER BY ord) id FROM unnest($2) with ordinality AS t(un, ord)

  ) x;

$arrexcept$ LANGUAGE sql;