Postgresql trigger run non stop?

Question

I try to work with trigger here. I have a relation like this :

salary(salaryid, userid, netsalary, reward, totalsalary)

So I want to update totalsalary everytime I insert and update (netsalary or reward), it will recount : totalsalary = netsalary + reward.

To do that, I made a function and a trigger :

CREATE FUNCTION reCount()
  RETURNS TRIGGER AS $function$
BEGIN 
  UPDATE salary SET totalsalary = netsalary + reward;
  RETURN NEW;
END;

CREATE TRIGGER updateTotalsalary
  AFTER INSERT OR UPDATE
  ON salary
  FOR EACH ROW
  EXECUTE PROCEDURE reCount();

Finally, I try to test by a query insert like this :

INSERT INTO salary(salaryid,userid,netsalary,reward,totalsalary) 
    VALUES (1234,123, 30,2,30);

but it run for a long time and it seem never stop. So when a try to stop it with, I got many rows of :

SQL statement "UPDATE salary SET totalsalary = netsalary + reward"
PL/pgSQL function "reCount()" line 3 at SQL statement

So what is the problem. Hope you guys can give me some suggestion?

Answer 1

Try:

CREATE TRIGGER updateTotalsalary 
AFTER INSERT OR UPDATE 
ON salary 
FOR EACH ROW
WHEN (pg_trigger_depth() = 0)
EXECUTE PROCEDURE reCount();

Answer 2

this might be better than the pg_trigger_depth() = 0 hack:

CREATE TRIGGER updateTotalsalary 
AFTER INSERT OR UPDATE OF netsalary, reward
ON salary 
FOR EACH ROW
EXECUTE PROCEDURE reCount();

For UPDATE events, it is possible to specify a list of columns using this syntax:

UPDATE OF column_name1 [, column_name2 ... ]

The trigger will only fire if at least one of the listed columns is mentioned as a target of the UPDATE command.

though personally i'd probably go for a table without the totalsalary column and a view with it (CREATE TABLE salary_ ..., CREATE VIEW salary AS SELECT ..., (salary + reward) AS totalsalary FROM salary_).