Glen Maisey created SPARK-16239:
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Summary: SQL issues with cast from date to string around daylight
savings time
Key: SPARK-16239
URL: https://issues.apache.org/jira/browse/SPARK-16239
Project: Spark
Issue Type: Bug
Components: SQL
Affects Versions: 1.6.1
Reporter: Glen Maisey
Priority: Critical
Hi all,
I have a dataframe with a date column. When I cast to a string using the spark
sql cast function it converts it to the wrong date on certain days. Looking
into it, it occurs once a year when summer daylight savings starts.
I've tried to show this issue the code below. The toString() function works
correctly whereas the cast does not.
Unfortunately my users are using SQL code rather than scala dataframes and
therefore this workaround does not apply. This was actually picked up where a
user was writing something like "SELECT date1 UNION ALL select date2" where
date1 was a string and date2 was a date type. It must be implicitly converting
the date to a string which gives this error.
I'm in the Australia/Sydney timezone (see the time changes here
http://www.timeanddate.com/time/zone/australia/sydney)
val dates =
Array("2014-10-03","2014-10-04","2014-10-05","2014-10-06","2015-10-02","2015-10-03",
"2015-10-04", "2015-10-05")
val df = sc.parallelize(dates)
.toDF("txn_date")
.select(col("txn_date").cast("Date"))
df.select(
col("txn_date"),
col("txn_date").cast("Timestamp").alias("txn_date_timestamp"),
col("txn_date").cast("String").alias("txn_date_str_cast"),
col("txn_date".toString()).alias("txn_date_str_toString")
)
.show()
+----------+--------------------+-----------------+---------------------+
| txn_date| txn_date_timestamp|txn_date_str_cast|txn_date_str_toString|
+----------+--------------------+-----------------+---------------------+
|2014-10-03|2014-10-02 14:00:...| 2014-10-03| 2014-10-03|
|2014-10-04|2014-10-03 14:00:...| 2014-10-04| 2014-10-04|
|2014-10-05|2014-10-04 13:00:...| 2014-10-04| 2014-10-05|
|2014-10-06|2014-10-05 13:00:...| 2014-10-06| 2014-10-06|
|2015-10-02|2015-10-01 14:00:...| 2015-10-02| 2015-10-02|
|2015-10-03|2015-10-02 14:00:...| 2015-10-03| 2015-10-03|
|2015-10-04|2015-10-03 13:00:...| 2015-10-03| 2015-10-04|
|2015-10-05|2015-10-04 13:00:...| 2015-10-05| 2015-10-05|
+----------+--------------------+-----------------+---------------------+
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