I could see that 'Time zone' is selected in both 'schedule' tab and 'output options' tab of JasperReports Server scheduler.
So, please clarify what is the use of selecting "Time zone" again under 'output options' tab of a Jasperserver even though we specified the Time zone under 'schedule' tab.
Also, can we remove/ignore 'Time zone' option under 'output options' tab?
This can be of use if your company or your customers are set up internationally.
Schedule time zone
This time zone is the zone which is being used to calculate correctly, at which hour the report should be generated. This is only used for the schedule of the generation. So one could set the generation time for a few countries to 8:00 in the morning just by selecting the correct time zone.
Output time zone
With this time zone you can set the report time zone. This means the calculation of time and date values can be changed separately for every reciepient. So for example the Europe office would get their share of data interpreted with Europe/Berlin and the asia office with settings for Asia/Malaysia. All times and dates will be set according to the time zone.
Related
I have a time field (LaborHed.ClockInTime) that in Epicor server (the ERP I'm using) has 1 hour difference from my local time. My local time zone is UTC (Dublin, Edinburgh, Lisbon, London). I don't know how to convert the Epicor server time zone to my local time zone.
I tried this code (but it doesn't work)
ShiftDateTime (cdate({BAQReportResult.LaborHed.ClockInTime}),"UTC,0",
"")
What I'm doing wrong?
If it's for a print field, increase the hour in the formula. Otherwise, this will use the current user time zone:
ShiftDateTime ( CurrentDateTime, PrintTimeZone, CurrentCEUserTimeZone)
To enforce a timezone, such as British summer time, use the following:
ShiftDateTime (cdate({BAQReportResult.LaborHed.ClockInTime}),"UTC,0, BST", "")
See reference to ShiftDateTime in Crystal Reports Online Help
ShiftDateTime (inputDateTime, inputTimeZone, newTimeZone)
Epicor server (the ERP I'm using) has 1 hour difference from my local time. My local time zone is UTC (Dublin, Edinburgh, Lisbon, London).
What I'm doing wrong?
You need to input the server time zone.
It looks as though ShiftDateTime (cdate({BAQReportResult.LaborHed.ClockInTime}),"UTC,0", "") inputs and outputs your local time.
how to convert the Epicor server time zone to my local time zone.
Since your local time is UTC/London, I'm assuming server time is UTC+1. Crystal Reports syntax for inputTimeZone and newTimeZone is "std,offset".
std = String name of the standard time zone.
offset = Offset, in minutes, of the standard time zone (west is positive).
Try this:
ShiftDateTime (cdate({BAQReportResult.LaborHed.ClockInTime}), "UTC,-60", "")
or write local time zone explicitly like this:
ShiftDateTime (cdate({BAQReportResult.LaborHed.ClockInTime}), "UTC,-60", "UTC,0")
I have column 'event_date_time' in my 'events' table with type 'timestamp with timezone'. My python flask application is saving date like '2014-08-30 02:17:02+00:00' but postgres automatically converts it to '2014-08-30 07:17:02+05'. It converts the timestamp to my local timezone i-e Pakistan. I want to save it without converting.
I have tried
set timezone='UTC'
and it does change timezone to 'UTC' but pgadmin3 is still saving the converted time.
I am using MAC OS and Postgresql 9.3.
The reason pgadmin is displaying hours +5 is because your system timezone is set to this.
When you save a "timestamp with time zone" value at GMT + or - any value, the system offsets whatever timezone your input was to GMT (or UTC), so that when you go to retrieve it, you can specify the timezone you want it displayed in.
For example let's establish a current time for say... New York.
select now()::timestamp with time zone at time zone 'America/New_York';
At the time of asking it returned '2014-08-23 08:50:57.136817'. 8:50 Saturday morning, or 8:51 if you're being pedantic.
Now if we take that same time and display it in GMT we will see a different result:
select '2014-08-23 08:50:57.136817 America/New_York'::timestamp with time zone at time zone 'GMT';
Now have a new time of '2014-08-23 12:50:57.136817'... 5 hours into the "future"!
Finally let's get the original timestamp and display it in what I believe is the Pakistan time zone (PKT) and see what it shows
select '2014-08-23 08:50:57.136817 America/New_York'::timestamp with time zone at time zone 'PKT';
The result? '2014-08-23 17:50:57.136817' further into the future still!
Again I must stress the reason it can do this is because it is always converting the input time offset to UTC or GMT. Postgres processes all of its "timestamp with time zone" data types in this way. It is designed to avoid time zone problems such as daylight savings and so on.
Your issue appears to be that python is inserting the time at an offset of +00, and if this was supposed to be a local time then you will be 5 hours off as far as postgres is concerned. Without knowing exactly what queries python is making, I would assume you may want to look at that to make sure it is giving you the correct time, presumably set timezone='PKT' should be a fix. Either way, when you are viewing timestamp with time zone using a browser such as pgadmin, the timestamp is being converted to your local timezone and this is why you see +5.
Alternatively if you do wish to see those times at +00 then you must specify that you want this in your SELECT queries.
I'm developing an app where a user can request that an email be sent to them at a specific time every day in their timezone. For example User A lives in London and schedules an email at 2pm every day London time and User B lives in New York and schedules an email at 2pm New York time.
I'm wondering what way I should configure my database postgres such that a scheduler can fire every minute and query for all emails to be sent at that minute regardless of what timezone their in.
The one thing I want to avoid is having to run multiple queries, once per timezone.
Due to the (rather idiotic, quite frankly) rules for daylight saving times (DST) across the world, a local time can mean all kind of things in absolute (UTC time).
Save a time (not timetz!) and the time zone name (not the abbreviation) for when to send the emails. Tricky details under this related question:
Time zone names with identical properties yield different result when applied to timestamp
CREATE TABLE event (
event_id serial PRIMARY KEY
, alarm_time time -- local alarm time
, tz text -- time zone name
, ...
);
Use the following expression to "cook" the exact daily point in time, taking local DST settings into account:
SELECT current_date + alarm_time AT TIME ZONE tz;
Example:
SELECT current_date + '2:30'::time AT TIME ZONE 'Europe/London' AS alarm_ts
Returns:
alarm_ts
2014-05-19 02:30:00+02
Use timestamp with time zone (timestamptz) across your whole application. Be sure to understand how it works. This comprehensive post may be of help (also explains the AT TIME ZONE construct:
Ignoring timezones altogether in Rails and PostgreSQL
Just to be clear, once you have "cooked" the daily UTC time, you can translate it to and work with any local time just as well. But it might be less confusing to do all the rest in UTC.
We're deploying our own stream gauges (a lot like this USGS gauge: http://waterdata.usgs.gov/usa/nwis/uv?site_no=03539600) so us kayakers know whether or not there's enough water to paddle the stream and don't waste time and gas to drive out there. We hope install a few of these across the southeast whitewater region which spans the eastern and central time zones.
I'm storing the time a record is inserted using the default value of current_time for the record. I'd like to later display the data using the MM/DD/YYYY HH12:MI AM TZ format, which outputs reading like 03/12/2012 01:00 AM CDT. I'd also like for the output to be aware of changes in day light savings time, so the last part of the previous sentence would change between CST and CDT when we 'spring forward' and 'fall back'. This change occurred on 3/11/2012 this year and I've included dates on both sides of this DST line below. I'm using my Windows 7 laptop for development and we will later be deploying on a Unix box. Postgres has apparently detected that my Windows computer is set to eastern US time zone. I'm trying this with a 'timestamp without time zone' field and a 'timestamp with time zone' field but can't get it to work.
I've tried using 'at time zone' in my selects and every thing is working until it's time to display the time zone. The actual hour is part of the time stamp is correctly subtracted by an hour when I ask for the time in CDT. But EDT is displayed in the output.
SELECT reading_time as raw,
reading_time at time zone 'CDT',
to_char(reading_time at time zone 'CDT',
'MM/DD/YYYY HH12:MI AM TZ') as formatted_time
FROM readings2;
"2012-04-29 17:59:35.65";"2012-04-29 18:59:35.65-04";"04/29/2012 06:59 PM EDT"
"2012-04-29 17:59:40.19";"2012-04-29 18:59:40.19-04";"04/29/2012 06:59 PM EDT"
"2012-03-10 00:00:00";"2012-03-10 00:00:00-05";"03/10/2012 12:00 AM EST"
"2012-03-11 00:00:00";"2012-03-11 00:00:00-05";"03/11/2012 12:00 AM EST"
"2012-03-12 00:00:00";"2012-03-12 01:00:00-04";"03/12/2012 01:00 AM EDT"
I'm storing the time zone that each of our gauges is located in a character varying field a separate table. I considered just appending this value to the end of the time output, but I want it to change from from CST to CDT without my intervention.
Thanks for your help.
Instead of using time zone abbreviations like CDT or CST, you could consider using full Olson-style time zone names. In the case of central time, you could choose a time zone. Either one that matches your location, such as America/Chicago, or just US/Central. This ensures PostgreSQL uses the Olson tz database to automatically figure out whether daylight saving time applies at any given date.
You definitely want a TIMESTAMP WITH TIME ZONE column (which is also known as timestamptz in PostgreSQL). That will store the timestamp in UTC, so that it represents a particular moment in time. Contrary to what the name suggests, it does not save a time zone in the column -- you can view the retrieved timestamp in the time zone of your choosing with the AT TIME ZONE phrase.
The semantics of TIMESTAMP WITHOUT TIME ZONE are confusing and nearly useless. I strongly recommend you don't use that type at all for what you are describing.
I'm really confused by the part of the question which talks about storing the timestamp in a CHARACTER VARYING column. That seems as though it might be part of the problem. If you can store it in timestamptz right from the start I suspect that you will have fewer problems. Barring that, it would be safest to use the -04 notation for offset from UTC; but that seems like more work to me for no benefit.
You can create a table of known timezones in the format suggested in Guan Yang's answer, and then use a foreign key column to this table. Valid timezones can be obtained from pg_timezone_names I've gone into more detail in this related answer.
I would like to define a best practice for storing timestamps in my Postgres database in the context of a multi-timezone project.
I can
choose TIMESTAMP WITHOUT TIME ZONE and remember which timezone was used at insertion time for this field
choose TIMESTAMP WITHOUT TIME ZONE and add another field which will contain the name of the timezone that was used at insertion time
choose TIMESTAMP WITH TIME ZONE and insert the timestamps accordingly
I have a slight preference for option 3 (timestamp with time zone) but would like to have an educated opinion on the matter.
First off, PostgreSQL’s time handling and arithmetic is fantastic and Option 3 is fine in the general case. It is, however, an incomplete view of time and timezones and can be supplemented:
Store the name of a user’s time zone as a user preference (e.g. America/Los_Angeles, not -0700).
Have user events/time data submitted local to their frame of reference (most likely an offset from UTC, such as -0700).
In application, convert the time to UTC and stored using a TIMESTAMP WITH TIME ZONE column.
Return time requests local to a user's time zone (i.e. convert from UTC to America/Los_Angeles).
Set your database's timezone to UTC.
This option doesn’t always work because it can be hard to get a user’s time zone and hence the hedge advice to use TIMESTAMP WITH TIME ZONE for lightweight applications. That said, let me explain some background aspects of this this Option 4 in more detail.
Like Option 3, the reason for the WITH TIME ZONE is because the time at which something happened is an absolute moment in time. WITHOUT TIME ZONE yields a relative time zone. Don't ever, ever, ever mix absolute and relative TIMESTAMPs.
From a programmatic and consistency perspective, ensure all calculations are made using UTC as the time zone. This isn’t a PostgreSQL requirement, but it helps when integrating with other programming languages or environments. Setting a CHECK on the column to make sure the write to the time stamp column has a time zone offset of 0 is a defensive position that prevents a few classes of bugs (e.g. a script dumps data to a file and something else sorts the time data using a lexical sort). Again, PostgreSQL doesn’t need this to do date calculations correctly or to convert between time zones (i.e. PostgreSQL is very adept at converting times between any two arbitrary time zones). To ensure data going in to the database is stored with an offset of zero:
CREATE TABLE my_tbl (
my_timestamp TIMESTAMP WITH TIME ZONE NOT NULL DEFAULT NOW(),
CHECK(EXTRACT(TIMEZONE FROM my_timestamp) = '0')
);
test=> SET timezone = 'America/Los_Angeles';
SET
test=> INSERT INTO my_tbl (my_timestamp) VALUES (NOW());
ERROR: new row for relation "my_tbl" violates check constraint "my_tbl_my_timestamp_check"
test=> SET timezone = 'UTC';
SET
test=> INSERT INTO my_tbl (my_timestamp) VALUES (NOW());
INSERT 0 1
It's not 100% perfect, but it provides a strong enough anti-footshooting measure that makes sure the data is already converted to UTC. There are lots of opinions on how to do this, but this seems to be the best in practice from my experience.
Criticisms of database time zone handling is largely justified (there are plenty of databases that handle this with great incompetence), however PostgreSQL’s handling of timestamps and timezones is pretty awesome (despite a few "features" here and there). For example, one such feature:
-- Make sure we're all working off of the same local time zone
test=> SET timezone = 'America/Los_Angeles';
SET
test=> SELECT NOW();
now
-------------------------------
2011-05-27 15:47:58.138995-07
(1 row)
test=> SELECT NOW() AT TIME ZONE 'UTC';
timezone
----------------------------
2011-05-27 22:48:02.235541
(1 row)
Note that AT TIME ZONE 'UTC' strips time zone info and creates a relative TIMESTAMP WITHOUT TIME ZONE using your target’s frame of reference (UTC).
When converting from an incomplete TIMESTAMP WITHOUT TIME ZONE to a TIMESTAMP WITH TIME ZONE, the missing time zone is inherited from your connection:
test=> SET timezone = 'America/Los_Angeles';
SET
test=> SELECT EXTRACT(TIMEZONE_HOUR FROM NOW());
date_part
-----------
-7
(1 row)
test=> SELECT EXTRACT(TIMEZONE_HOUR FROM TIMESTAMP WITH TIME ZONE '2011-05-27 22:48:02.235541');
date_part
-----------
-7
(1 row)
-- Now change to UTC
test=> SET timezone = 'UTC';
SET
-- Create an absolute time with timezone offset:
test=> SELECT NOW();
now
-------------------------------
2011-05-27 22:48:40.540119+00
(1 row)
-- Creates a relative time in a given frame of reference (i.e. no offset)
test=> SELECT NOW() AT TIME ZONE 'UTC';
timezone
----------------------------
2011-05-27 22:48:49.444446
(1 row)
test=> SELECT EXTRACT(TIMEZONE_HOUR FROM NOW());
date_part
-----------
0
(1 row)
test=> SELECT EXTRACT(TIMEZONE_HOUR FROM TIMESTAMP WITH TIME ZONE '2011-05-27 22:48:02.235541');
date_part
-----------
0
(1 row)
The bottom line:
store a user’s time zone as a named label (e.g. America/Los_Angeles) and not an offset from UTC (e.g. -0700)
use UTC for everything unless there is a compelling reason to store a non-zero offset
treat all non-zero UTC times as an input error
never mix and match relative and absolute timestamps
also use UTC as the timezone in the database if possible
Random programming language note: Python's datetime data type is very good at maintaining the distinction between absolute vs relative times (albeit frustrating at first until you supplement it with a library like PyTZ).
EDIT
Let me explain the difference between relative vs absolute a bit more.
Absolute time is used to record an event. Examples: "User 123 logged in" or "a graduation ceremonies start at 2011-05-28 2pm PST." Regardless of your local time zone, if you could teleport to where the event occurred, you could witness the event happening. Most time data in a database is absolute (and therefore should be TIMESTAMP WITH TIME ZONE, ideally with a +0 offset and a textual label representing the rules governing the particular timezone - not an offset).
A relative event would be to record or schedule the time of something from the perspective of a yet-to-be-determined time zone. Examples: "our business's doors open at 8am and close at 9pm", "let's meet every Monday at 7am for a weekly breakfast meeting," or "every Halloween at 8pm." In general, relative time is used in a template or factory for events, and absolute time is used for almost everything else. There is one rare exception that’s worth pointing out which should illustrate the value of relative times. For future events that are far enough in the future where there could be uncertainty about the absolute time at which something could occur, use a relative timestamp. Here’s a real world example:
Suppose it’s the year 2004 and you need to schedule a delivery on October 31st in 2008 at 1pm on the West Coast of the US (i.e. America/Los_Angeles/PST8PDT). If you stored that using absolute time using ’2008-10-31 21:00:00.000000+00’::TIMESTAMP WITH TIME ZONE , the delivery would have shown up at 2pm because the US Government passed the Energy Policy Act of 2005 that changed the rules governing daylight savings time. In 2004 when the delivery was scheduled, the date 10-31-2008 would have been Pacific Standard Time (+8000), but starting in year 2005+ timezone databases recognized that 10-31-2008 would have been Pacific Daylight Savings time (+0700). Storing a relative timestamp with the time zone would have resulted in a correct delivery schedule because a relative timestamp is immune to Congress’ ill-informed tampering. Where the cutoff between using relative vs absolute times for scheduling things is, is a fuzzy line, but my rule of thumb is that scheduling for anything in the future further than 3-6mo should make use of relative timestamps (scheduled = absolute vs planned = relative ???).
The other/last type of relative time is the INTERVAL. Example: "the session will time out 20 minutes after a user logs in". An INTERVAL can be used correctly with either absolute timestamps (TIMESTAMP WITH TIME ZONE) or relative timestamps (TIMESTAMP WITHOUT TIME ZONE). It is equally correct to say, "a user session expires 20min after a successful login (login_utc + session_duration)" or "our morning breakfast meeting can only last 60 minutes (recurring_start_time + meeting_length)".
Last bits of confusion: DATE, TIME, TIME WITHOUT TIME ZONE and TIME WITH TIME ZONE are all relative data types. For example: '2011-05-28'::DATE represents a relative date since you have no time zone information which could be used to identify midnight. Similarly, '23:23:59'::TIME is relative because you don't know either the time zone or the DATE represented by the time. Even with '23:59:59-07'::TIME WITH TIME ZONE, you don't know what the DATE would be. And lastly, DATE with a time zone is not in fact a DATE, it is a TIMESTAMP WITH TIME ZONE:
test=> SET timezone = 'America/Los_Angeles';
SET
test=> SELECT '2011-05-11'::DATE AT TIME ZONE 'UTC';
timezone
---------------------
2011-05-11 07:00:00
(1 row)
test=> SET timezone = 'UTC';
SET
test=> SELECT '2011-05-11'::DATE AT TIME ZONE 'UTC';
timezone
---------------------
2011-05-11 00:00:00
(1 row)
Putting dates and time zones in databases is a good thing, but it is easy to get subtly incorrect results. Minimal additional effort is required to store time information correctly and completely, however that doesn’t mean the extra effort is always required.
Sean's answer is overly complex and misleading.
The fact is that both "WITH TIME ZONE" and "WITHOUT TIME ZONE" store the value as a unix-like absolute UTC timestamp. The difference is all in how the timestamp is displayed. When "WITH time zone" then the displayed value is the UTC stored value translated to the user's zone. When "WITHOUT time zone" the UTC stored value is twisted so as to show the same clock face no matter what zone the user has set".
The only situation where a "WITHOUT time zone" is usable is when a clock face value is applicable regardless of actual zone. For example, when a timestamp indicates when voting booths might close (ie. they close at 20:00 regardless of a person's timezone).
Use choice 3. Always use "WITH time zone" unless there is a very specific reason not to.
My preference is towards option 3, as Postgres can then do al ot of the work recalculating timestamps relative to timezone for you, whereas with the other two you'll have to do that yourself. The extra storage overhead of storing the timestamp with a timezone is really negligible unless you're talking millions of records, in which case you probably already have pretty meaty storage requirements anyway.