Re: Using timestamp in function

On Tue, Oct 05, 2004 at 05:37:51PM +0200, Silke Trissl wrote:

> CREATE or replace FUNCTION mylog_test(integer, varchar) RETURNS 
> timestamp AS '
>     DECLARE
>         n ALIAS FOR $1;
>         logtxt ALIAS FOR $2;
>         curtime timestamp;
>     BEGIN
>         curtime := ''now'';
>         --INSERT INTO logger VALUES ( nextval(''seq_log''), curtime, 
> substr(logtxt,0,200));
>         RAISE NOTICE ''TIME: %'',curtime;
>         RETURN curtime;
>     END;
> ' LANGUAGE plpgsql;
> 
> I expected, that the variable curtime gets a new time value, each time 
> the function is called (at least that is what I understood from the 
> documentation). This works fine, if I test it with
> SELECT mylog_test(5, 'test');
> But as soon as I call the funtion from another function (which I need) 
> the variable curtime does not change anymore.

"Functions and trigger procedures are always executed within a
transaction established by an outer query...." [1]

"It is important to know that CURRENT_TIMESTAMP and related functions
return the start time of the current transaction; their values do not
change during the transaction....timeofday() returns the wall-clock
time and does advance during transactions." [2]

[1] http://www.postgresql.org/docs/7.4/static/plpgsql-structure.html
[2] http://www.postgresql.org/docs/7.4/static/functions-datetime.html#FUNCTIONS-DATETIME-CURRENT

-- 
Michael Fuhr
http://www.fuhr.org/~mfuhr/