Apex 4.1 bug? Application language derived from Session changes time zone

Question

I have created an application in Apex 4.1 and in the "Initialization PL/SQL Code" for the session (what used to be called the VPD section) I have the following code:
begin
  execute immediate 'alter session set time_zone = ''+01:00''';
end;This works as expected, UNLESS the "Application Language Derived From" (under "Edit Globalization Attributes") is set to "Session", in which case the session's time zone is also affected (and not just the language, as one would expect).
This can be seen in the following simple example, which runs the above code to set the time zone, and has the language derived from "Session":
http://apex.oracle.com/pls/apex/f?p=38595
This shows
sessiontimezone = -05:00Even though the session's time_zone has been explicitly set to +01:00 with the ALTER SESSION statement.
Experimentation with the URL shows that if a p_lang parameter is passed, with a valid language identifier, for example:
http://apex.oracle.com/pls/apex/f?p=38595&p_lang=de
then the time zone is affected (showing -05:00 instead of +01:00).
However, if an INVALID time zone identifier is passed:
http://apex.oracle.com/pls/apex/f?p=38595&p_lang=xx
then the session time zone is CORRECT according to the ALTER SESSION command:
sessiontimezone = +01:00If I change the "Application Language Derived From" to something else than "Session" (for example, "Browser" or "Item Preference"), then the timezone is also correct (ie follows the ALTER SESSION command).
Running the page in debug mode confirms that the time zone is being set after my VPD/initialization code has been run:
0.01585     0.00146     ...Application session: 1671806996734123, user=nobody     4     
0.01731     0.00144     ...Execute Statement: begin begin execute immediate 'alter session set time_zone = ''+01:00'''; end; end;     4     
0.01875     0.00065     Session: Fetch session header information     4     
0.01940     0.00073     SESSION Language (nobody): wwv_flow.g_browser_language=en maplang=en     4     
0.02013     0.00059     alter session set nls_language="AMERICAN"     4     
0.02071     0.00043     alter session set nls_territory="AMERICA"     4     
0.02114     0.00094     NLS: CSV charset=WE8MSWIN1252     4     
0.02208     0.00111     ...NLS: Set Decimal separator="."     4     
0.02318     0.00062     ...NLS: Set NLS Group separator=","     4     
0.02380     0.00063     ...NLS: Set g_nls_date_format="DD-MON-RR"     4     
0.02443     0.00091     ...NLS: Set g_nls_timestamp_format="DD-MON-RR HH.MI.SSXFF AM"     4     
0.02534     0.00066     ...NLS: Set g_nls_timestamp_tz_format="DD-MON-RR HH.MI.SSXFF AM TZR"     4     
0.02600     0.00050     ...Setting session time_zone to -05:00     4     
0.02650     0.00065     Setting NLS_DATE_FORMAT to application date format: dd.mm.yyyy     4     
0.02715     0.00056     ...NLS: Set g_nls_date_format="dd.mm.yyyy"     4     
0.02771     0.00055     ...NLS: Set g_nls_timestamp_format="DD-MON-RR HH.MI.SSXFF AM"     4     
0.02827     0.00057     ...NLS: Set g_nls_timestamp_tz_format="DD-MON-RR HH.MI.SSXFF AM TZR"     4     
0.02884     0.00230     NLS: Language=en     4     
Conclusion: It seems to me that when the LANGUAGE is set to be derived from the "Session", this also, as a side effect, alters the session TIME ZONE, which must be a bug... ?
- Morten
http://ora-00001.blogspot.com
Edited by: mobra on Sep 24, 2011 7:14 PM

Answer 1

Hi Arie,
When you are setting the language to derived from session you actually declare that you are working in a dynamic environment – per session – and not in a static one. Using the Initialization PL/SQL Code is very static as the same code is executed for every database session.I was using a fixed time zone value in the ALTER SESSION to demonstrate the bug/problem... in real life, the actual time zone is derived dynamically based on a user profile stored in the database.
APEX 4.0 introduced the Automatic Time Zone under the Globalization tab. By default it’s set to No but setting it to Yes will allow you to use your local time zone (as derived from your browser) with whatever language derived setting you choose, including per session with the *&p_lang* parameter.The key point is that LANGUAGE has nothing to do with TIME ZONEs, and vice versa. People speak English (and Spanish, and French, and Chinese for that matter) all over the world. You cannot determine a user's time zone based on the chosen language.
You're telling me to enable "Automatic Time Zone" to work around an unwanted side effect from changing the language setting. Sorry, but that just sounds like bad advice to me.
If you want to use session derived language, however the local time zone settings are not good for you, you can still change them with a Before Header and After Submit PL/SQL processes and an appropriate alter session statement, on a per page base. The APEX engine will not ignore a page based session setting.Why should I have to do this for every page when the "VPD" Section (now called "Initialization PL/SQL Code") is made for this purpose?
If you look at the help text in the Apex builder for that section, it actually says that:
The code entered here need not pertain to VPD/FGAC and may not be related to security at all.
Any code that needs to be executed at the earliest point in a page request can be placed here.
For example, the following code sets the database session time zone for every page request:
BEGIN
   EXECUTE IMMEDIATE 'alter session set time_zone = ''Australia/Sydney'' ';
END;So I hope the demonstrated behavior is not intentional, but a bug, and I'm hoping Joel sees it the same way.
- Morten
http://ora-00001.blogspot.com