I've faced today a weird problem: I have a function which is called by job. I want to find the difference from start of the function till the end to log it then to some table.
So, let's say I have function
procedure p is
starttime timestamp := systimestamp;
procedure writeTime
is
diff interval day to second := systimestamp - starttime;
begin
-- here insert diff to some table
end;
begin
-- doing some long stuff
writeTime();
exception
when others then
writeTime();
end;
The problem in the function is:
When I run this manually, it works well, difference is clear. E.g. I use extract to parse the interval: extract(hour from diff)*60*60 + extract(minute from diff)*60 + extract(second from diff)
When I set up the job and the job runs this function I have a big problem: it returns negative result, which as I, after some tests, understand is generated here systimestamp - starttime. Seems like systimestamp in this calculation is taken from Greenwich timezone, and mine is one hour bigger, so this calculation diff interval day to second := systimestamp - starttime; is returning the value like (-1 hour + difference).
By stupid brute-forcing I've found a solution:
procedure p is
starttime timestamp := systimestamp;
procedure writeTime
is
diff interval day to second;
endtime timestamp := systimestamp;
begin
diff := endtime - starttime;
-- here insert diff to some table
end;
begin
-- doing some long stuff
writeTime();
exception
when others then
writeTime();
end;
which simply writes systimestamp in the variable first, and only then calculates the difference.
My database parameters:
Oracle 11.2.0.2.0
Timezone +1 Berlin
So now the question: I really want to know is it a bug of my RDBMS or perhaps I do not see some obvious explanation why it is like that? The concrete question is: why during this operation
starttime timestamp := systimestamp;
it takes one timezone and during this
diff interval day to second := systimestamp - starttime;
it takes another one in the same procedure of the same session with the same settings?
Is the database timezone DBTIMEZONE the same like your session timezone SESSIONTIMEZONE?
Function SYSTIMESTAMP returns datatye TIMESTAMP WITH TIME ZONE, so you do an implicit convertion into TIMESTAMP datatype.
Datatype of LOCALTIMESTAMP is TIMESTAMP.
Try
starttime timestamp WITH TIME ZONE := systimestamp;
or
starttime timestamp := LOCALTIMESTAMP;
You can check with this query in which timezone the Schedule Jobs are running:
SELECT * FROM ALL_SCHEDULER_GLOBAL_ATTRIBUTE where attribute_name = 'DEFAULT_TIMEZONE'
I'm using this approach
declare
time_start number;
begin
time_start := dbms_utility.get_time();
-- some heavy lifting
dbms_output.put_line(dbms_utility.get_time() - time_start);
end;
/
Related
I have a procedure.It takes date parameter with type Date.What i want to know is the other users send sysdate to my procedure.Which format they send sysdate to my procedure?
For example:
01/02/2021 or 01/02/2020 00:00:00(timestamp)
Does my procedure accepts all sending formats?Maybe Date type converts sending formats this style 01/02/2020.I am not sure.
I mean that does my Date parameter accepts all date formats because I want to use date in my procedure without seconds or minutes.
My procedure is
DECLARE
var_P_DATE DATE; (for example : 01/01/2021)
BEGIN
SELECT last_day(var_P_DATE) INTO v_last_day FROM DUAL; (31/01/2021)
if v_last_day = var_P_DATE (it returns false because no second or minutes)
.....
END;
I used DBMS.OUTPUT. I think Date type converts just like this 01/02/2021 and i do not get any error but i am not sure.
Your procedure will only ever receive a date, because that is the data type of the formal parameter. When the procedure is called the caller can supply a date, or something that can be implicitly converted to a date (though they shouldn't; implicit conversions are generally a bad thing, particularly from strings).
The date data type includes time components. If you are being passed a date with a non-midnight time that you want to ignore, such as sysdate, you can use the trunc() function, with it's default 'DD' format; and you don't need to select from dual:
v_last_day := last_day(trunc(var_P_DATE));
If the caller passes in systimestamp then that will still be implcitly converted to a date by the time you see it - which means it loses any fractional seconds and time zone information, but retains hours, minutes and seconds.
Dates and timestamps do not have have any inherent human-readable format. A date can be displayed using various formats - see the documentation - either explicitly with to_char() and a format model, or implicitly using your session settings.
When you do
dbms_output.put_line(var_P_DATE);
you are doing an implicit conversion of the date value to a string, using the session's NLS_DATE_FORMAT setting. So, different users might see that in different formats. You have no control over that. If you want to see a specific format then specify that, e.g.:
dbms_output.put_line(to_char(var_P_DATE, 'YYYY-MM-DD'));
You also have no control over whether the caller sees that output - it's down to the application/client and its settings. It looks like you are probably only using it for debugging the comparison issue though, so that probably doesn't matter here.
So as a demonstration:
declare
var_P_DATE date := sysdate;
v_last_day date;
begin
v_last_day := last_day(var_P_DATE);
dbms_output.put_line(to_char(v_last_day, 'YYYY-MM-DD HH24:MI:SS'));
v_last_day := last_day(trunc(var_P_DATE));
dbms_output.put_line(to_char(v_last_day, 'YYYY-MM-DD HH24:MI:SS'));
end;
/
2021-02-28 09:59:02
2021-02-28 00:00:00
db<>fiddle demo
Date type in Oracle has hours, minutes and seconds, timestamp has fractions:
SQL> declare
2 vDate date := sysdate;
3 vTimeStamp timestamp := systimestamp;
4 begin
5 dbms_output.put_line('Date: ' || vDate);
6 dbms_output.put_line('Timestamp: ' || vTimestamp);
7 end;
8 /
Date: 2021-02-18 09:49:32
Timestamp: 18-FEB-21 09.49.32.015953 AM
If you want to use just the date part, with no time, of a date variable, use something like trunc(vDate):
SQL> declare
2 vDate date := sysdate;
3 vTimeStamp timestamp := systimestamp;
4 begin
5 dbms_output.put_line('Date: ' || vDate);
6 dbms_output.put_line('Date truncated: ' || trunc(vDate));
7 dbms_output.put_line('Timestamp: ' || vTimestamp);
8 end;
9 /
Date: 2021-02-18 09:51:51
Date truncated: 2021-02-18 00:00:00
Timestamp: 18-FEB-21 09.51.51.024384 AM
An example of how comparison works on date variables:
SQL> declare
2 vDate1 date;
3 vDate2 date;
4 begin
5 vDate1 := sysdate;
6 dbms_lock.sleep(5); /* wait 5 seconds */
7 vDate2 := sysdate;
8 --
9 if vDate1 = vDate2 then
10 dbms_output.put_line('Equal');
11 else
12 dbms_output.put_line('NOT equal');
13 end if;
14 --
15 if trunc(vDate1) = trunc(vDate2) then
16 dbms_output.put_line('Equal, truncated');
17 else
18 dbms_output.put_line('NOT equal, truncated');
19 end if;
20 end;
21 /
NOT equal
Equal, truncated
Just apply TRUNC() function and use that variable of type DATE within the procedure after defining the data type of var_P_DATE as TIMESTAMP
CREATE OR REPLACE PROCEDURE myproc( var_P_DATE TIMESTAMP) AS
dt DATE := TRUNC(var_P_DATE) ;
BEGIN
...
...
END;
/
If you mean DBMS_OUTPUT.PUT_LINE by DBMS.OUTPUT, then that's completely irrelevant with your current conversion, that's just used to display result to the console as a string.
I have the following stored procedure which calculates the time taken for a merge statement
create or replace procedure ModAuditData(
O_UpdatedCount out int
,O_EndTime out timestamp
,O_Duration out int)
as
P_StartTime timestamp(3) WITH LOCAL TIME ZONE;
-- EndTime timestamp;
begin
P_StartTime:=to_timestamp(to_char(current_timestamp,'DD/MM/YYYY HH:MI:SS'),'DD/MM/YYYY HH:MI:SS');
-- merge Statment that does UPSERT
O_UpdatedCount :=SQL%ROWCOUNT;
commit;
O_EndTime:=to_timestamp(to_char(current_timestamp,'DD/MM/YYYY HH:MI:SS'),'DD/MM/YYYY HH:MI:SS');
begin
select extract( second from (O_EndTime-P_StartTime) )
into O_Duration
from dual;
Exception When others then
O_Duration:=0;
end;
end ModAuditData;
The Issue is
O_EndTime:=to_timestamp(to_char(current_timestamp,'DD/MM/YYYY HH:MI:SS'),'DD/MM/YYYY HH:MI:SS')
gives exact opposite of
P_StartTime:=to_timestamp(to_char(current_timestamp,'DD/MM/YYYY HH:MI:SS'),'DD/MM/YYYY HH:MI:SS');
in terms of AM/PM
What is the correct way to calculate the start and end time
CURRENT_TIMESTAMP is already a TIMESTAMP WITH TIME ZONE, there is no reason to convert it first to VARCHAR2 and then back again into a TIMESTAMP.
Also timestamp(3) (which provides precision up to millisecond) does not make much sense when you return duration as INTEGER, i.e. full seconds.
Try it like this:
P_StartTime timestamp(3) WITH TIME ZONE;
begin
P_StartTime := current_timestamp;
-- merge Statment that does UPSERT
O_UpdatedCount :=SQL%ROWCOUNT;
commit;
O_Duration := EXTRACT(SECOND FROM (current_timestamp - P_StartTime));
end;
In case of SQL*Plus consider to use TIMING command.
I'm getting a strange error when trying to convert TIMESTAMP value to a timezone given as parameter (variable).
The code below throws ORA-00907 exception:
ORA-00907: missing right parenthesis
declare
tz timestamp := current_timestamp;
v_timezone varchar2(100) := '03:00';
tz2 timestamp;
begin
-- select (tz at time zone '03:00') into tz2 from dual;
select (tz at time zone v_timezone)
into tz2
from dual;
dbms_output.put_line(to_char(tz2,'hh24:mi:ss'));
-- dbms_output.put_line(to_char((tz at time zone v_timezone),'hh24:mi:ss'));
end;
At the same time, both SQL with string literal (first commented line) and PL/SQL with variable (second commented line) work just fine.
What could be the issue with variable in SQL? And why ORA-00907?
You need to just enclose the v_timezone variable inside braces (), see your code as below
declare
tz timestamp := current_timestamp;
v_timezone varchar2(100) := '03:00';
tz2 timestamp;
begin
-- select (tz at time zone '03:00') into tz2 from dual;
-- either use it as
-- select tz at time zone (v_timezone)
-- or
-- select (tz at time zone (v_timezone) )
select (tz at time zone (v_timezone) )
into tz2
from dual;
dbms_output.put_line(to_char(tz2,'hh24:mi:ss'));
-- dbms_output.put_line(to_char((tz at time zone v_timezone),'hh24:mi:ss'));
end;
AT TIME ZONE requires a literal or an expression:
expr AT
{ LOCAL
| TIME ZONE { ' [ + | - ] hh:mi'
| DBTIMEZONE
| 'time_zone_name'
| expr
}
}
It doesn't like a variable. It seems that the variable is being implicitly seen as an expression inside the dbms_output call, or any PL/SQL context (as Wernfried pointed out, just tz2 := tz at time zone v_timezone works too), which is a bit strange; but the same thing isn't happening in a SQL context.
You can just force your variable into an expression by enclosing that in parentheses, or call a dummy function:
declare
tz timestamp := current_timestamp;
v_timezone varchar2(100) := '03:00';
tz2 timestamp;
begin
-- select (tz at time zone '03:00') into tz2 from dual;
select tz at time zone (v_timezone)
into tz2
from dual;
dbms_output.put_line(to_char(tz2,'hh24:mi:ss'));
-- dbms_output.put_line(to_char((tz at time zone v_timezone),'hh24:mi:ss'));
end;
PL/SQL procedure successfully completed.
17:45:41
Essentially, remove the redundant parentheses you have now, and use dummy ones around the variable. You can use a function instead, like upper(v_timezone), but it isn't necessary - just the parentheses to make it be evaluated as an expression are enough. Strange but works... It's mentioned in bug 6113282 and seems to worked like this since 9i.
I have bunch of Oracle sysdate values which need to be converted to Unix epoch time in ms.
For example variable that has value
15-MAR-13
should convert to
1363351108398
in PL/SQL
How would one do that ?
You can use this function. It also considers the time zone, because Unix epoche is 1970-01-01 00:00:00 UTC!
CREATE OR REPLACE FUNCTION GetEpoche(theTimestamp IN TIMESTAMP, timezone IN VARCHAR2 DEFAULT SESSIONTIMEZONE) RETURN NUMBER DETERMINISTIC IS
timestampUTC TIMESTAMP;
theInterval INTERVAL DAY(9) TO SECOND;
epoche NUMBER;
BEGIN
timestampUTC := FROM_TZ(theTimestamp, timezone) AT TIME ZONE 'UTC';
theInterval := TO_DSINTERVAL(timestampUTC - TO_TIMESTAMP('1970-01-01', 'YYYY-MM-DD') );
epoche := EXTRACT(DAY FROM theInterval)*24*60*60
+ EXTRACT(HOUR FROM theInterval)*60*60
+ EXTRACT(MINUTE FROM theInterval)*60
+ EXTRACT(SECOND FROM theInterval);
RETURN ROUND(1000*epoche);
END GetEpoche;
Is there a way in Oracle to select the date on which daylight savings will switch over for my locale?
Something vaguely equivalent to this would be nice:
SELECT CHANGEOVER_DATE
FROM SOME_SYSTEM_TABLE
WHERE DATE_TYPE = 'DAYLIGHT_SAVINGS_CHANGEOVER'
AND TO_CHAR(CHANGEOVER_DATE,'YYYY') = TO_CHAR(SYSDATE,'YYYY'); -- in the current year
Edit: I was hoping for a solution that would not require changes when Congress adjusts DST laws, as they did in 2007. The posted solutions will work, though.
To improve on Leigh Riffel's answer, this is much simpler with the same logic:
Function DaylightSavingTimeStart (p_Date IN Date)
Return Date Is
Begin
Return NEXT_DAY(TO_DATE(to_char(p_Date,'YYYY') || '/03/01 02:00 AM', 'YYYY/MM/DD HH:MI AM') - 1, 'SUN') + 7;
End;
Function DaylightSavingTimeEnd (p_Date IN Date)
Return Date Is
Begin
Return NEXT_DAY(TO_DATE(to_char(p_Date,'YYYY') || '/11/01 02:00 AM', 'YYYY/MM/DD HH:MI AM') - 1, 'SUN');
End;
We use the following two functions to calculate the start and end dates for any given year (post 2007, US).
Function DaylightSavingTimeStart (p_Date IN Date)
Return Date Is
v_Date Date;
v_LoopIndex Integer;
Begin
--Set the date to the 8th day of March which will effectively skip the first Sunday.
v_Date := to_date('03/08/' || to_char(p_Date,'YYYY') || '02:00:00 AM','MM/DD/YYYY HH:MI:SS PM');
--Advance to the second Sunday.
FOR v_LoopIndex IN 0..6 LOOP
If (RTRIM(to_char(v_Date + v_LoopIndex,'DAY')) = 'SUNDAY') Then
Return v_Date + v_LoopIndex;
End If;
END LOOP;
End;
Function DaylightSavingTimeEnd (p_Date IN Date)
Return Date Is
v_Date Date;
v_LoopIndex Integer;
Begin
--Set Date to the first of November this year
v_Date := to_date('11/01/' || to_char(p_Date,'YYYY') || '02:00:00 AM','MM/DD/YYYY HH:MI:SS PM');
--Advance to the first Sunday
FOR v_LoopIndex IN 0..6 LOOP
If (RTRIM(to_char(v_Date + v_LoopIndex,'DAY')) = 'SUNDAY') Then
Return v_Date + v_LoopIndex;
End If;
END LOOP;
End;
There is probably a simpler way to do it, but these have worked for us. Of course this query doesn't know whether daylight saving time is observed for where you are. For that you will need location data.
Instead of looping to get the next sunday you can also use the next_day(date, 'SUN') function of oracle.
In the United States, Daylight Savings Time is defined as beginning on the second Sunday in March, and ending on the first Sunday in November, for the areas that observe DST, for years after 2007.
I don't think there's an easy way to get this information from Oracle, but based on the standard definition, you should be able to write a stored procedure that calculates the beginning and ending date using the Doomsday Algorithm.
Here is a way to use Oracles internal knowledge of whether a timezone observes daylight saving time or not to determine the start and end of it. Aside from the complexity and general strangeness of it, it requires two timezones to be know have identical times when daylight saving time is not in effect and different times when it is. As such it is resilient to congressional changes in when daylight saving time occurs (assuming your database is up to date with the patches), but is not resilient to regional changes effecting the timezones keyed off of. With those warnings, here is what I have.
ALTER SESSION SET time_zone='America/Phoenix';
DROP TABLE TimeDifferences;
CREATE TABLE TimeDifferences(LocalTimeZone TIMESTAMP(0) WITH LOCAL TIME ZONE);
INSERT INTO TimeDifferences
(
SELECT to_date('01/01/' || to_char(sysdate-365,'YYYY') || '12:00:00','MM/DD/YYYYHH24:MI:SS')+rownum-1
FROM dual CONNECT BY rownum<=365
);
COMMIT;
ALTER SESSION SET time_zone='America/Edmonton';
SELECT LocalTimeZone-1 DaylightSavingTimeStartAndEnd
FROM
(
SELECT LocalTimeZone,
to_char(LocalTimeZone,'HH24') Hour1,
LEAD(to_char(LocalTimeZone,'HH24')) OVER (ORDER BY LocalTimeZone) Hour2
FROM TimeDifferences
)
WHERE Hour1 <> Hour2;
I told you it was strange. The code only figures out the day of the change, but could be enhanced to show the hour. Currently it returns 09-MAR-08 and 02-NOV-08. It is also sensitive to the time of year it is run, which is why I had to do the -365...+365. All in all I don't recommend this solution, but it was fun to investigate. Maybe someone else has something better.
Here's my version of the above. It's advantage is that it does not need a second 'alter session set time zone', and can be used more easily from an application.
You create the stored function, and then you simply use:
ALTER SESSION SET time_zone='Asia/Jerusalem';
select GetDSTDates(2012,1) DSTStart,GetDSTDates(2012,2) DSTEnd,SessionTimeZone TZ from dual;
which will return the dst start date,dst end date, timezone for the specified year.
create or replace function GetDSTDates
(
year integer,
GetFrom integer
)
return Date
as
cursor c is
select 12-to_number(to_char(LocalTimeZone at time zone '+00:00','HH24')) offset,
min(to_char(LocalTimeZone at time zone '+00:00','DD/MM/YYYY')) fromdate,
max(to_char(LocalTimeZone at time zone '+00:00','DD/MM/YYYY')) todate
from (
SELECT cast((to_date('01/01/'||to_char(year)||'12:00:00','MM/DD/YYYYHH24:MI:SS')+rownum-1) as timestamp with local time zone) LocalTimeZone
FROM dual CONNECT BY rownum<=365
)
group by 12-to_number(to_char(LocalTimeZone at time zone '+00:00','HH24'));
dstoffset integer;
offset integer;
dstfrom date;
dstto date;
begin
offset := 999;
dstoffset := -999;
for rec in c
loop
if rec.offset<offset
then
offset := rec.offset;
end if;
if rec.offset>dstoffset
then
dstoffset := rec.offset;
dstfrom := to_date(rec.fromdate,'DD/MM/YYYY');
dstto :=to_date(rec.todate,'DD/MM/YYYY');
end if;
end loop;
if (offset<999 and dstoffset>-999 and offset<>dstoffset)
then
if GetFrom=1
then
return dstfrom;
else
return dstto;
end if;
else
return null;
end if;
end;
/
ALTER SESSION SET time_zone='Asia/Jerusalem';
select GetDSTDates(2012,1) DSTStart,
GetDSTDates(2012,2) DSTEnd,
SessionTimeZone TZ from dual;
Old question but here's a new answer. Use 08-MAR for the first date since that skips the first week
--Start of DST
select next_day(to_date('08-MAR-' || to_char(sysdate, 'YYYY')), 'SUN') from dual
--End of DST
select next_day(to_date('01-NOV-' || to_char(sysdate, 'YYYY')), 'SUN') from dual