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https://issues.apache.org/jira/browse/DERBY-7091?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17234993#comment-17234993
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Richard N. Hillegas commented on DERBY-7091:
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The SQL Standard TIMESTAMP type does not include timezone information. The
Standard does define a TIMESTAMP WITH TIME ZONE type, but Derby does not
support that. Derby TIMESTAMPs carry no timezone information.
I can see that it would be useful to have more documentation about how Derby
TIMESTAMPs behave with respect to reading/writing across timezones and shifts
between winter and summer time. The issues which are frustrating you are
probably similar to the ones which caused the SQL committee to introduce a
TIMESTAMP WITH TIME ZONE type and which caused Java to introduce the java.time
package in Java 8.
The gory details of Derby TIMESTAMP handling are coded in the class
org.apache.derby.iapi.types.SQLTimestamp.
> Times Inserted Incorrectly Around Daylight Savings Time Change in Spring
> ------------------------------------------------------------------------
>
> Key: DERBY-7091
> URL: https://issues.apache.org/jira/browse/DERBY-7091
> Project: Derby
> Issue Type: Bug
> Affects Versions: 10.14.2.0
> Environment: Java 14.0.1
> Reporter: Larry Melvin Lemons
> Priority: Critical
> Attachments: Test.java, Timezone_Data_Inconsistencies.odt
>
>
> When inserting date/times into the timestamp field around the daylight
> savings time change in the Spring, the times are inconsistent. I am in/use
> the New York EST/EDT timezone, but the data I am inserting is Standard time
> and not Daylight Savings Time
> All the times are correct up to 1:48AM, then when it inserts 2:00 AM the data
> in the database is 3:00AM. That could be alright if it kept switching the
> time to Daylight Savings Time, however going from inserting 2:48AM and
> getting 3:48AM in the database, when it inserts 3:00AM it shows 3:00AM in the
> database, not the expected 4:00AM. Then in the fall whatever is inserted in
> the database is what shows in the database around the daylight savings time
> switch to standard time. See the attached Open Document Text file for
> examples of what is actually inserted and what is showing in the database.
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