----- Original Message -----
From: "Lew" <noone@xxxxxxxxxxxxxxxxxxxxxxx>
To: <pgsql-general@xxxxxxxxxxxxxx>
Sent: Saturday, May 23, 2009 2:18 PM
Subject: Re: Daylight saving time question
Bayless Kirtley wrote:
Thanks Tom and Scott. You got me looking in the right direction. In this
case
the client and server are on the same machine (testing/development) and
psql
does return the right result. I tried all the possibilities from the java
program,
"show timezone", "select current_time" and "select current_timestamp".
These
were all JDBC queries. When I used result.getString(), the values looked
right. When I used result.getTime(), they were off by one hour as if
daylight saving were not in effect.
If 'result' is a Java 'java.util.Date' type (or one of its java.sql
subtypes), then it only holds milliseconds since epoch as if in GMT;
'Date' holds no timezone information as such. In that situation,
'result.getTime()' returns a 'long' value.
How exactly are you displaying 'result.getTime()'? How exactly are you
determining that its value is "off" by one hour? Can you show us Java
code?
Is this a flaw in the JDBC driver or is that the expected behavior? In
either case I do now have a workaround but would like to know.
It is not a flaw in the JDBC driver.
--
Lew
--
Here is a simplified and tested version of the exact Java code.
private void run() {
try {
Statement stmt = connection.createStatement();
ResultSet result = stmt.executeQuery("Select CURRENT_TIME");
result.next();
String timeStr = result.getString(1);
System.out.println("String: " + timeStr);
java.sql.Time time = result.getTime(1);
System.out.println("Time: " + time);
java.sql.Time sysTime = new java.sql.Time(new
java.util.Date().getTime());
System.out.println("Run at:" + sysTime);
}
catch (SQLException e) {
System.out.println(e.getMessage());
}
}
The output from running this code is:
String: 09:17:46.427-05
Time: 08:17:46
Run at: 09:17:46
As you can see it was run at 09:17:46 local daylight saving time today.
Retrieving Postgres time as a String also gives that same value.
Retrieving it as a Time gives a value of one hour earlier. Presumably
it is not recognizing daylight saving time. Since it produces two quite
different values for the same query, I would suggest that this is in fact
a flaw in the JDBC driver, unless, of course, it is actually intended to
behave in that manner for some reason I am not aware of.
As stated earlier, the driver in use is "org.postgresql.Driver" and I
am using PostgreSQL 8.3.1-1, installed about a year ago.
Bayless
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