Create type ComprositionPrixod AS (
    Id bigint,
    Name character varying,
    Count bigint,
    Price double precision
);

CREATE TABLE "Prixod" (
   "id" serial NOT NULL,
   "Date" timestamp without time zone,
   "OrgPostav" character varying,
   "NameSklad" character varying,
   "Сomposition" ComprositionPrixod[],
   "Operator" character varying,
   "Total" double precision DEFAULT sum(),
   CONSTRAINT Prixod_pk PRIMARY KEY ("id")
) WITH (
   OIDS=FALSE
);

select sum(u.price) from unnest(Сomposition) u

CREATE OR REPLACE FUNCTION prixod_trigger_func() RETURNS trigger AS $TRIGGER$
BEGIN
    NEW."Total" = (select sum(u.price) from unnest(NEW."Сomposition") u);
    return NEW;
END;
$TRIGGER$
LANGUAGE  plpgsql;

CREATE TRIGGER prixod_trigger
BEFORE INSERT OR UPDATE ON "Prixod" FOR EACH ROW
EXECUTE PROCEDURE prixod_trigger_func();.