Trigger on 2 tables : issue with INSERT and UPDATE

This is related to my previous question: https://dba.stackexchange.com/questions/213913/trigger-to-cascade-updates-to-a-second-table . In my Postgres 9.6 DB, I had 2 triggers on emprise (formerly table1), supposed to insert or update some fields in metadonnees (formerly table2). Merged like this now: CREATE OR REPLACE FUNCTION activite.tbl_emprise_metadonnees() RETURNS trigger AS $BODY$ begin IF (TG_OP = 'INSERT') THEN insert into activite.metadonnees (gid, date_publication, contributor, code_tranche) VALUES (new.gid, current_date, current_user, NEW.code_tranche) ; return new ; elseif (TG_OP = 'DELETE') THEN DELETE from activite.metadonnees where gid = old.gid ; return old ; elsif (TG_OP = 'UPDATE') THEN UPDATE activite.metadonnees SET (contributor, code_tranche) = (current_user, NEW.code_tranche) where metadonnees.gid = new.gid ; return new ; end if ; end; $BODY$ LANGUAGE plpgsql VOLATILE COST 100; CREATE TRIGGER trg_tbl_emprise_metadonnees AFTER INSERT OR DELETE OR UPDATE ON activite.emprise FOR EACH ROW EXECUTE PROCEDURE activite.tbl_emprise_metadonnees(); Table definitions: CREATE TABLE activite.emprise (gid integer NOT NULL DEFAULT PRIMARY KEY nextval('activite.emprise_gid_seq'::regclass), surface numeric(9,2), annee integer, ro character varying(50), numope character varying(12), typope character varying(25), geom geometry(MultiPolygon,2154), typemp character varying(30), nomope character varying(80), numoa character varying(20), numprescr character varying(25), tranche integer DEFAULT 1, code_tranche character varying(15), producteur character varying(15), notice_rapport character varying(50) CREATE TABLE activite.metadonnees (gid integer NOT NULL PRIMARY KEY, date_publication date, "date_création" date, "généalogie" character varying(250), "résolution_spatiale" character varying(5), responsable character varying(10), restrictions character varying(100), source character varying(15), creator character varying(50), publisher character varying(80), identifier character varying(50), title character varying(80), subject character varying, code_tranche character varying(15), contributor character varying, dates character varying, type_donnees character, format character varying, language character varying, coverage character varying If I use AFTER INSERT OR DELETE OR UPDATE trigger then when a record is inserted into emprise, the field contributor is overwritten by the current_user value for all records. If the trigger is limited to AFTER INSERT OR DELETE then after insertion everything goes well: the field contributor is not replaced for all records (as desired), just the record concerned in emprise. In both cases, the contributor and code_tranche are updated if, after insertion, code_tranche value is changed in table emprise. I will conclude that UPDATE is the cause of this dysfunction but I am unable to find why.