[SQL] multiple insert

[van Elsacker Frans]

We developed a program to follow up the time one is working on a 
particular job. They start and stop the time counter different times a 
day, now for already tree years.  Everything works fine but for a short 
while (august?) there are very few actions  from which the beginning 
time is inserted twice, even three times, without special reason. Now 
this occurs a mean of once/two days. We disabled the possibility of 
double clicking on the insert button to avoid double inserting but it 
did not help. The table has appr 40.000 records now.
Employes have same working times and lunch times.( more ticks can have 
same second for start)
vacuum runed.
Can the problem be caused by a heavy loaded server??

The structure of the table is :
CREATE TABLE tikbezig (
   ordernr character(6) NOT NULL,
   lijnnr character(2),
   afdeling character(2),
   werknr character(5),
   begintijd timestamp with time zone,               --startime
   eindtijd timestamp with time zone,               --endtime
   begincomp character varying(20),                  -- computername 
startjob
   eindcomp character varying(20),                  --computername endjob
   oo integer,
time zone
);

ordernr is not unique but has a index
CREATE INDEX tikbezig_idx ON tikbezig USING btree (ordernr, lijnnr, 
afdeling);

CREATE INDEX tikwerkn_idx ON tikbezig USING btree (werknr);
CREATE CONSTRAINT TRIGGER "<unnamed>"
   AFTER INSERT OR UPDATE ON tikbezig
   FROM werkn
   NOT DEFERRABLE INITIALLY IMMEDIATE
   FOR EACH ROW
   EXECUTE PROCEDURE "RI_FKey_check_ins"('<unnamed>', 'tikbezig', 
'werkn', 'UNSPECIFIED', 'werknr', 'nr');

example
13474     01    NA        3    2004-09-24 11:02:50    2004-09-24 
11:09:43    NAAIAFDELING    NAAIAFDELING        2004-09-24 11:09:28
13474     01    NA        3    2004-09-24 11:02:50    2004-09-24 
11:09:35    NAAIAFDELING    NAAIAFDELING        2004-09-24 11:09:31
13474     01    NA        3    2004-09-24 11:02:50    2004-09-24 
11:10:12    NAAIAFDELING    NAAIAFDELING        2004-09-24 11:09:26
which means same computer, same person, same order on same second.

Any help is welcome
Frans
---------------------------(end of broadcast)---------------------------
TIP 8: explain analyze is your friend