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=================================
Upgrading from PySpark 2.2 to 2.3
=================================

* In PySpark, now we need Pandas 0.19.2 or upper if you want to use Pandas related functionalities, such as ``toPandas``, ``createDataFrame`` from Pandas DataFrame, etc.

* In PySpark, the behavior of timestamp values for Pandas related functionalities was changed to respect session timezone. If you want to use the old behavior, you need to set a configuration ``spark.sql.execution.pandas.respectSessionTimeZone`` to False. See `SPARK-22395 <https://issues.apache.org/jira/browse/SPARK-22395>`_ for details.

* In PySpark, ``na.fill()`` or ``fillna`` also accepts boolean and replaces nulls with booleans. In prior Spark versions, PySpark just ignores it and returns the original Dataset/DataFrame.

* In PySpark, ``df.replace`` does not allow to omit value when ``to_replace`` is not a dictionary. Previously, value could be omitted in the other cases and had None by default, which is counterintuitive and error-prone.