7.2.8. Time Zones

Time zones are another headache when using batch loading. For best results applications should standardize on a single time zone, preferably UTC, and use this consistently for all data. To ensure the Java VM outputs time data correctly to CSV files, you must set the JVM time zone to be the same as the standard time zone for your data. Here is the JVM setting in wrapper.conf:

# To ensure consistent handling of dates in heterogeneous and batch replication
# you should set the JVM timezone explicitly.  Otherwise the JVM will default
# to the platform time, which can result in unpredictable behavior when
# applying date values to slaves.  GMT is recommended to avoid inconsistencies.


Beware that MySQL has two very similar data types: TIMESTAMP and DATETIME. Timestamps are stored in UTC and convert back to local time on display. Datetimes by contrast do not convert back to local time. If you mix timezones and use both data types your time values will be inconsistent on loading.