Changing the default Java TimeZone does not work with createConnectionForPool

The problem is described as follows:

(1) I change the default Java TimeZone within MATLAB using the following command

java.util.TimeZone.setDefault(java.util.TimeZone.getTimeZone('UTC'));

(2) I initialize a parallel pool with JDBC Database Connection

c = createConnectionForPool( gcp , datasource , username , password )

(3) I run a parfor loop with fetch queries

parfor i = 1 : i_max
    allresults{i} = fetch(c.Value,sqlqueries(i));
end

(4) The problem is that the time-data that i am fetching arrive with local TimeZone and not UTC as specified in step (1).

Step (1) is necessary for my script to overcome the issue described here:

https://www.mathworks.com/matlabcentral/answers/65526-has-anyone-else-encountered-the-jdbc-daylight-savings-time-bug

Could you please assist me with the above?

Answer 1

[Andrew Janke]

Each of the workers in the Parallel Pool is a separate process with its own separate JVM. You need to run that java.util.TimeZone.setDefault(java.util.TimeZone.getTimeZone('UTC')); in each of your workers, and not just in your base Matlab session.

Answer 2

[Allan Brett]

For anyone coming here because of the issue discussed here (https://www.mathworks.com/matlabcentral/answers/1468926-why-do-i-get-the-following-jdbc-driver-error-the-server-time-zone-value-cdt-is-unrecognized-or-r), but running into an issue with parallel pool database connections (createConnectionForPool). You need to manually set the connection options.

datasource = "some_source";

opts = databaseConnectionOptions(datasource);

opts = setoptions(opts,'URL','jdbc:mysql://127.0.0.1:3306/yoursever?serverTimezone='yourtimezonehere'');

saveAsDataSource(opts)