Trigger changes visibility - Mailing list pgsql-bugs

Hello,

I'm having an unexpected behaviour when executing an 'after delete' trigger.

In PostgreSQL 8.0.0beta5 documentation, section 33.2 "Visibility of Data
Changes", it is said that "When a row-level after trigger is fired, all
data changes made by the outer command are already complete, and are
visible to the invoked trigger function".

In my case, when executing a DELETE sql statement, the next trigger is
executed:

===============================================

CREATE OR REPLACE FUNCTION "public"."DisparadorHijoBorradoCMin1" ()
RETURNS trigger AS
$body$
DECLARE
   temporal INTEGER;

BEGIN

   SELECT INTO temporal count(*) FROM "Hijo" WHERE
"Hijo"."IDPadre"=OLD."IDPadre" AND "Hijo"."IDHijo"!=OLD."IDHijo";
   RAISE NOTICE 'number of Rows: %', temporal;

   IF temporal < 1 THEN
      RAISE EXCEPTION 'ERROR DE BORRADO';
      RETURN NULL;
   END IF;

   RETURN NULL;
END
$body$
LANGUAGE 'plpgsql' IMMUTABLE CALLED ON NULL INPUT SECURITY INVOKER;


CREATE TRIGGER "BorradoCMin1" AFTER DELETE
ON "public"."Hijo" FOR EACH ROW
EXECUTE PROCEDURE "public"."DisparadorHijoBorradoCMin1"();

===============================================

The problem is that the row's count done by the trigger is the same
number of rows that appears in the table before de delete was executed.
There was no other user trigger in the database.

I've send the database script attached to this mail.


Thanks in advance.

Antonio


CREATE TABLE "public"."Padre" (
  "IDPadre" SERIAL,
  "DatoPadre" CHAR(18) NOT NULL,
  CONSTRAINT "PKPadre" PRIMARY KEY("IDPadre")
) WITHOUT OIDS;



CREATE TABLE "public"."Hijo" (
  "IDHijo" SERIAL,
  "DatoHijo" CHAR(28) NOT NULL,
  "IDPadre" INTEGER NOT NULL,
  CONSTRAINT "PKHijo" PRIMARY KEY("IDHijo"),
  CONSTRAINT "gg" FOREIGN KEY ("IDPadre")
    REFERENCES "public"."Padre"("IDPadre")
    MATCH FULL
    ON DELETE RESTRICT
    ON UPDATE CASCADE
    DEFERRABLE
    INITIALLY DEFERRED
) WITHOUT OIDS;

CREATE INDEX "fki_FKPadre-Hijo" ON "public"."Hijo"
  USING btree ("IDPadre");

CREATE OR REPLACE FUNCTION "public"."compruebaenhijo" (identificador integer) RETURNS boolean AS
$body$
/* New function body */
DECLARE
   temporal "Hijo"%ROWTYPE;

BEGIN
   SELECT INTO temporal * FROM "Hijo" WHERE "Hijo"."IDPadre"=identificador;
   IF NOT FOUND THEN
      RETURN false;
   END IF;
   RETURN true;
END
$body$
LANGUAGE 'plpgsql' VOLATILE RETURNS NULL ON NULL INPUT SECURITY INVOKER;

ALTER TABLE "Padre" ADD  CONSTRAINT "Padre_check0" CHECK (compruebaenhijo("IDPadre"));




CREATE OR REPLACE FUNCTION "public"."DisparadorHijoBorradoCMin1" () RETURNS trigger AS
$body$
DECLARE
   temporal INTEGER;

BEGIN

   SELECT INTO temporal count(*) FROM "Hijo" WHERE "Hijo"."IDPadre"=OLD."IDPadre";
   RAISE NOTICE 'number of rows %', temporal;


   IF temporal < 1 THEN
      RAISE EXCEPTION 'ERROR DE BORRADO';
      RETURN NULL;
   END IF;

   RETURN NULL;
END
$body$
LANGUAGE 'plpgsql' IMMUTABLE CALLED ON NULL INPUT SECURITY INVOKER;


CREATE TRIGGER "BorradoCMin1" AFTER DELETE
ON "public"."Hijo" FOR EACH ROW
EXECUTE PROCEDURE "public"."DisparadorHijoBorradoCMin1"();


begin;

insert into "Hijo" values (1,'dd',1);

insert into "Hijo" values (2,'dd',1);

insert into "Hijo" values (3,'dd',1);

insert into "Padre" values (1,'pp');

commit;


-- the error comes here!!
-- for every row, the trigger gets executed,
-- but always returns that there are 3 rows,
-- the same that were before executing DELETE.

delete from "Hijo";