Toby Harradine created SPARK-32123:
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Summary: [Python] Setting `spark.sql.session.timeZone` only
partially respected
Key: SPARK-32123
URL: https://issues.apache.org/jira/browse/SPARK-32123
Project: Spark
Issue Type: Bug
Components: PySpark
Affects Versions: 2.3.1
Reporter: Toby Harradine
The setting `spark.sql.session.timeZone` is respected by PySpark when
converting from and to Pandas, as described
[here|http://spark.apache.org/docs/latest/sql-programming-guide.html#timestamp-with-time-zone-semantics].
However, when timestamps are converted directly to Pythons `datetime` objects,
its ignored and the systems timezone is used.
This can be checked by the following code snippet
{code:java}
import pyspark.sql
spark = (pyspark
.sql
.SparkSession
.builder
.master('local[1]')
.config("spark.sql.session.timeZone", "UTC")
.getOrCreate()
)
df = spark.createDataFrame([("2018-06-01 01:00:00",)], ["ts"])
df = df.withColumn("ts", df["ts"].astype("timestamp"))
print(df.toPandas().iloc[0,0])
print(df.collect()[0][0])
{code}
Which for me prints (the exact result depends on the timezone of your system,
mine is Europe/Berlin)
{code:java}
2018-06-01 01:00:00
2018-06-01 03:00:00
{code}
Hence, the method `toPandas` respected the timezone setting (UTC), but the
method `collect` ignored it and converted the timestamp to my systems timezone.
The cause for this behaviour is that the methods `toInternal` and
`fromInternal` of PySparks `TimestampType` class don't take into account the
setting `spark.sql.session.timeZone` and use the system timezone.
If the maintainers agree that this should be fixed, I would try to come up with
a patch.
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