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Re: [eclipselink-users] MySQL's datetime and time-zones? 
Hello Gili,

Just to clarify, what is the database type you are persisting the calendar object into, and does it keep the timezone info?

If you are using a Timestamp type in the database (one without timezone info for instance) EclipseLink will pull out the timestamp info from the calendar.  As timestamps are just wrappers on the long value underneath, this is timezone independent anyway.  Unless you have turned binding off, the timestamp passed to the driver will not have any timezone information - though if you have logging showing the SQL being used, it will display the timestamp as in the server timezone since that is a java default.

When you read back (refresh) from the database, your calendar object would not have the timezone preserved, and so the time would appear to be shifted into the default server time-zone.  ie 3pm pst would print off as 6pm est for me.  
Is this what is occuring for you?


Best Regards,
Chris

----- Original Message -----
From: "Cowwoc" <cowwoc@xxxxxxxxxxxxxxxx>
To: "Eclipselink-Users" <eclipselink-users@xxxxxxxxxxx>
Sent: Monday, December 15, 2008 12:18:05 o'clock PM (GMT-0500) America/New_York
Subject: Re: [eclipselink-users] MySQL's datetime and time-zones?


I think I found a bug. It looks like EclipseLink is persisting Calendar
wrong. My property getter returns a Calendar relative to the UTC time-zone
and it issues an SQL insert command relative to the *local* time zone.

Please verify you can reproduce this on your end.

Thank you,
Gili


James Sutherland wrote:
> 
> EclipseLink does not store the timezone in the database by default. In
> JDBC Timestamps are normally written as a java.sql.Timestamp, which has no
> concept of a timezone.  You should get back the exact timestamp you write,
> irregardless of what timezone you are in, Timestamp has no timezone.
> 
> EclipseLink does have extended support for store the timezone in the
> database on Oracle.  It has support for both TIMESTAMPTZ and TIMESTAMPLTZ
> fields.
> 
> I do not believe MySQL supports storing the timezone in the database, it
> does have a session level timezone, which will be used to convert the
> timestamp value to and from UTC.  If you are having issues with your
> timezone, you could try setting the connection timezone using, 
> 
> SET time_zone = :timezone;
> 
> You could set this server property using an EclipseLink postConnect
> SessionEvent.
> 
> If you are having timezone issues, you could also try using a Converter on
> your mapping (@Convert).
> 
> There is some info on JPA and timezones here,
> http://en.wikibooks.org/wiki/Java_Persistence/Basic_Attributes#Timezones
> 
> 
> 
> cowwoc wrote:
>> 
>> Hi,
>> 
>> What's the implication of using EclipseLink to store dates in MySQL
>> "datetime" columns? By the looks of it EclipseLink stores the date using
>> the current time-zone. Shouldn't EclipseLink converts dates to UTC before
>> passing them on to MySQL? Otherwise, what will happen if the server
>> time-zone changes?
>> 
>> Thank you,
>> Gili
>> 
> 
> 

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