Logon Trigger setting NLS_SESSION_PARAMETERS not working

Question

Hello,
I have a problem with a logon trigger setting session parameters:
create or replace
TRIGGER standard.after_logon_trg
AFTER LOGON ON STANDARD.SCHEMA
BEGIN
  DBMS_APPLICATION_INFO.set_module(USER, 'Initialized');
  EXECUTE IMMEDIATE ('ALTER SESSION SET current_schema=standard');
  EXECUTE IMMEDIATE ('ALTER SESSION SET NLS_DATE_LANGUAGE=''AMERICAN''');
  EXECUTE IMMEDIATE ('ALTER SESSION SET NLS_TERRITORY=''AMERICA''');
  EXECUTE IMMEDIATE ('ALTER SESSION SET NLS_TIMESTAMP_FORMAT=''HH24:mi:ss''');
  EXECUTE IMMEDIATE ('ALTER SESSION SET NLS_DATE_FORMAT=''YYYY-MM-DD''');
  EXECUTE IMMEDIATE ('ALTER SESSION SET NLS_COMP=LINGUISTIC');
  EXECUTE IMMEDIATE ('ALTER SESSION SET NLS_SORT=BINARY_CI');
  insert into standard.testcc (bezeichnung, datum) values ('logontrigger', SYSDATE);
END;After I log in, the new row is added to the table, but the session parameters are completely untouched.
select * from NLS_SESSION_PARAMETERS says:
NLS_LANGUAGE     GERMAN
NLS_TERRITORY     GERMANY
NLS_CURRENCY     €
NLS_ISO_CURRENCY     GERMANY
NLS_NUMERIC_CHARACTERS     ,.
NLS_CALENDAR     GREGORIAN
NLS_DATE_FORMAT     DD.MM.RR
NLS_DATE_LANGUAGE     GERMAN
NLS_SORT     GERMAN
NLS_TIME_FORMAT     HH24:MI:SSXFF
NLS_TIMESTAMP_FORMAT     DD.MM.RR HH24:MI:SSXFF
NLS_TIME_TZ_FORMAT     HH24:MI:SSXFF TZR
NLS_TIMESTAMP_TZ_FORMAT     DD.MM.RR HH24:MI:SSXFF TZR
NLS_DUAL_CURRENCY     €
NLS_COMP     BINARY
NLS_LENGTH_SEMANTICS     BYTE
NLS_NCHAR_CONV_EXCP     FALSEIf I execute the ALTER SESSION statements in the sql console (as user standard) they work perfectly, so this seems to be no permission issue.
Whats wrong with the trigger?
Thanks and regards
Christian
Edited by: 853536 on 20.04.2011 00:31
OK, I've traced the entire database, and found out that my parameters are overwritten. So after my trigger has been executed, the NLS Session parameters are altered, for example:
=====================
PARSING IN CURSOR #4 len=386 dep=0 uid=40 oct=3 lid=40 tim=4721509708 hv=302297662 ad='ab275c28'
select parameter,value from nls_session_parameters
union all SELECT 'DB_TIMEZONE' name, DBTIMEZONE  value FROM DUAL
union all SELECT 'SESSION_TIMEZONE' name, SESSIONTIMEZONE value FROM DUAL
union all SELECT 'SESSION_TIMEZONE_OFFSET' name, TZ_OFFSET(SESSIONTIMEZONE) value from DUAL
union all SELECT parameter, value FROM nls_database_parameters WHERE parameter='NLS_CHARACTERSET'
END OF STMT
PARSE #4:c=0,e=3962,p=0,cr=4,cu=0,mis=1,r=0,dep=0,og=1,tim=4721509705
EXEC #4:c=0,e=21,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,tim=4721509816
FETCH #4:c=0,e=111,p=0,cr=0,cu=0,mis=0,r=10,dep=0,og=1,tim=4721509976
FETCH #4:c=0,e=132,p=0,cr=0,cu=0,mis=0,r=10,dep=0,og=1,tim=4721510598
FETCH #4:c=0,e=204,p=0,cr=3,cu=0,mis=0,r=1,dep=0,og=1,tim=4721511118
STAT #4 id=1 cnt=21 pid=0 pos=1 obj=0 op='UNION-ALL  (cr=3 pr=0 pw=0 time=264 us)'
STAT #4 id=2 cnt=17 pid=1 pos=1 obj=0 op='FIXED TABLE FULL X$NLS_PARAMETERS (cr=0 pr=0 pw=0 time=128 us)'
STAT #4 id=3 cnt=1 pid=1 pos=2 obj=0 op='FAST DUAL  (cr=0 pr=0 pw=0 time=1 us)'
STAT #4 id=4 cnt=1 pid=1 pos=3 obj=0 op='FAST DUAL  (cr=0 pr=0 pw=0 time=0 us)'
STAT #4 id=5 cnt=1 pid=1 pos=4 obj=0 op='FAST DUAL  (cr=0 pr=0 pw=0 time=1 us)'
STAT #4 id=6 cnt=1 pid=1 pos=5 obj=96 op='TABLE ACCESS FULL PROPS$ (cr=3 pr=0 pw=0 time=194 us)'
=====================
PARSING IN CURSOR #3 len=41 dep=0 uid=40 oct=42 lid=40 tim=4721512239 hv=2321140216 ad='ab275184'
alter session set NLS_TERRITORY='GERMANY'
END OF STMT
PARSE #3:c=0,e=329,p=0,cr=0,cu=0,mis=1,r=0,dep=0,og=1,tim=4721512236
EXEC #3:c=0,e=48,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,tim=4721512424
=====================
PARSING IN CURSOR #2 len=35 dep=0 uid=40 oct=42 lid=40 tim=4721513208 hv=2785092162 ad='ab274e88'
alter session set NLS_SORT='GERMAN'
END OF STMT
PARSE #2:c=0,e=283,p=0,cr=0,cu=0,mis=1,r=0,dep=0,og=1,tim=4721513205
EXEC #2:c=0,e=20,p=0,cr=0,cu=0,mis=0,r=0,dep=0,og=1,tim=4721513370
=====================
...This explains why they are overwritten, but I still don't know why the session parameters are altered after my trigger at all. Any idea?
Edited by: 853536 on 20.04.2011 01:24
Problem solved: I was using Oracle SQL Developer to edit my trigger and to try it - and SQL Developer seems to ovewrite the NLS_Session parameters. Duh.
Edited by: 853536 on 20.04.2011 02:04

Answer 1

Yes, SQL Developer will usually override the settings. It should not do this if you go to Tools->Preferences->Database->NLS and check "Skip NLS Settings".
But, any program using JDBC OCI will also override most of the settings. Therefore, you should not rely on the database to fix the NLS settings. It is applications' job to prepare the NLS environment correctly (if the standard initialization based on the O/S settings and/or NLS_LANG is not satisfactory).
-- Sergiusz