Mutating table (urgent)

Hi,

 

I'm having a big throuble with postgreSQL, called "mutating table"

 

This problem also happen with Oracle,
but we found a soluction creating packagers.

 

In first.
I would like to explain that this exemple is just a exemple.
Don't try to understand its utility.

 

Step to emulation the error:

 

1) Creating a principal table and a child table
   CREATE TABLE PAI(CODPAI INTEGER PRIMARY KEY, NOMPAI VARCHAR(30));
   CREATE TABLE FILHO(CODPAI INTEGER, CODFIL SERIAL, NOMFIL VARCHAR(30), PRIMARY KEY (CODPAI, CODFIL));

 

2) Creating constraint between principal and child table
   ALTER TABLE FILHO ADD CONSTRAINT FK_PAI_FILHO FOREIGN KEY (CODPAI) REFERENCES PAI (CODPAI);

 

3) Creating trigger on principal table
   CREATE OR REPLACE FUNCTION TR_AIPAI() RETURNS OPAQUE AS '
   BEGIN
    INSERT INTO FILHO (CODPAI, NOMFIL) VALUES (NEW.CODPAI, ''FILHO DO PAI''||NEW.CODPAI);
    RETURN NULL;
   END;
   ' language 'plpgsql';

 

   CREATE TRIGGER AIPAI AFTER  INSERT ON PAI FOR EACH ROW EXECUTE PROCEDURE TR_AIPAI();

 

If we taking a insert on principal table it will insert on child table,
until here, thats all right...

 

4) Create a trigger on child table that make a select on principal table
   CREATE OR REPLACE FUNCTION TR_SELECT_PAI() RETURNS OPAQUE AS'
   DECLARE I INTEGER;
   BEGIN
    SELECT COUNT(*) INTO I FROM PAI;
    RETURN NULL;
   END;
   'language 'plpgsql';

 

   CREATE TRIGGER BIFILHO BEFORE INSERT ON FILHO FOR EACH ROW EXECUTE PROCEDURE TR_SELECT_PAI();

 

In this moment when we insert a register on principal table
it don't insert the register on child table, neither send any error message.

 

If anybody can help me, I'll be thanks for ever.

 

Cristian Custodio