Constant dates gets different values when instantiated using different cale

Question

Hi,
I have a package that's like this:
CREATE OR REPLACE PACKAGE DATABASE_SYS IS
first_julian_day_ CONSTANT NUMBER := 2378211;
last_julian_day_ CONSTANT NUMBER := 2545125;
first_calendar_date_ CONSTANT DATE := to_date(first_julian_day_, 'J');
last_calendar_date_ CONSTANT DATE := to_date(last_julian_day_, 'J');
FUNCTION Get_First_Calendar_Date RETURN DATE DETERMINISTIC;
PRAGMA restrict_references(Get_First_Calendar_Date, WNDS);
FUNCTION Get_Last_Calendar_Date RETURN DATE DETERMINISTIC;
PRAGMA restrict_references(Get_Last_Calendar_Date, WNDS);
END DATABASE_SYS;
CREATE OR REPLACE PACKAGE BODY DATABASE_SYS IS
FUNCTION Get_First_Calendar_Date RETURN DATE DETERMINISTIC
IS
BEGIN
RETURN first_calendar_date_;
END Get_First_Calendar_Date;
FUNCTION Get_Last_Calendar_Date RETURN DATE DETERMINISTIC
IS
BEGIN
RETURN last_calendar_date_;
END Get_Last_Calendar_Date;
END DATABASE_SYS;
If using two different SQLPlus sessions:
First session
SQL> ALTER SESSION SET nls_calendar='PERSIAN'
2 /
Session õr õndrad.
SQL> SELECT to_char(database_sys.Get_First_Calendar_Date, 'YYYY-MM-DD') FROM dual
2 /
TO_CHAR(DA
1799-03-21
SQL>
SQL> ALTER SESSION SET nls_calendar='GREGORIAN'
2 /
Session õr õndrad.
SQL> SELECT to_char(database_sys.Get_First_Calendar_Date, 'YYYY-MM-DD') FROM dual
2 /
TO_CHAR(DA
2420-06-10
SQL>
SQL> ALTER SESSION SET nls_calendar='PERSIAN'
2 /
Session õr õndrad.
SQL> SELECT to_char(database_sys.Get_First_Calendar_Date, 'YYYY-MM-DD') FROM dual
2 /
TO_CHAR(DA
1799-03-21
SQL>
SQL> ALTER SESSION SET nls_calendar='GREGORIAN'
2 /
Session õr õndrad.
SQL> SELECT to_char(database_sys.Get_First_Calendar_Date, 'YYYY-MM-DD') FROM dual
2 /
TO_CHAR(DA
2420-06-10
SQL>
Second session:
SQL> ALTER SESSION SET nls_calendar='GREGORIAN'
2 /
Session õr õndrad.
SQL> SELECT to_char(database_sys.Get_First_Calendar_Date,'YYYY-MM-DD') FROM dual
2 /
TO_CHAR(DA
1799-03-21
SQL>
SQL> ALTER SESSION SET nls_calendar='PERSIAN'
2 /
Session õr õndrad.
SQL> SELECT to_char(database_sys.Get_First_Calendar_Date, 'YYYY-MM-DD') FROM dua
l
2 /
TO_CHAR(DA
1178-01-01
SQL>
SQL> ALTER SESSION SET nls_calendar='GREGORIAN'
2 /
Session õr õndrad.
SQL> SELECT to_char(database_sys.Get_First_Calendar_Date,'YYYY-MM-DD') FROM dual
2 /
TO_CHAR(DA
1799-03-21
SQL>
SQL> ALTER SESSION SET nls_calendar='PERSIAN'
2 /
Session õr õndrad.
SQL> SELECT to_char(database_sys.Get_First_Calendar_Date, 'YYYY-MM-DD') FROM dua
l
2 /
TO_CHAR(DA
1178-01-01
SQL>
Why does the dates differ?
Should not the dates be the same?
Should not Julian dates always be the same regardless of my session parameters?
What am I missing here?
Regards
Håkan

Answer 1

The problem seems to be with Julian date conversion code being sensitive to the user calendar, while it should not be:
SQL> alter session set nls_date_format='YYYY-MM-DD';
Session altered.
SQL> select to_date('2378211','J','NLS_CALENDAR=GREGORIAN') from dual;
TO_DATE('2
1799-03-21
SQL> select to_date('2378211','J','NLS_CALENDAR=PERSIAN') from dual;
TO_DATE('2
2420-06-10
I have logged bug #5386942. If you want to follow this bug, you have to contact Oracle Support.
As a workaround, specify explicit third parameter 'NLS_CALENDAR=GREGORIAN' in your TO_DATE() calls.
-- Sergiusz