Felipe Olmos created SPARK-22049:
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Summary: Confusing behavior of from_utc_timestamp and
to_utc_timestamp
Key: SPARK-22049
URL: https://issues.apache.org/jira/browse/SPARK-22049
Project: Spark
Issue Type: Question
Components: SQL
Affects Versions: 2.1.0
Reporter: Felipe Olmos
Priority: Minor
Hello everyone,
I am confused about the behavior of the functions {{from_utc_timestamp}} and
{{to_utc_timestamp}}. As an example, take the following code to a spark shell
{code:java}
import java.sql.Timestamp
import org.apache.spark.sql.Row
import org.apache.spark.sql.types._
// 2017-07-14 02:40 UTC
val rdd = sc.parallelize(Row(new Timestamp(1500000000000L)) :: Nil)
val df = spark.createDataFrame(rdd, StructType(StructField("date",
TimestampType) :: Nil))
df.select(df("date"), from_utc_timestamp(df("date"), "GMT+01:00") as
"from_utc", to_utc_timestamp(df("date"), "GMT+01:00") as "to_utc").show(1,
false)
// Date format printing is dependent on the timezone of the machine.
// The following is in UTC
// +---------------------+---------------------+---------------------+
// |date |from_utc |to_utc |
// +---------------------+---------------------+---------------------+
// |2017-07-14 02:40:00.0|2017-07-14 03:40:00.0|2017-07-14 01:40:00.0|
// +---------------------+---------------------+---------------------+
df.select(unix_timestamp(df("date")) as "date",
unix_timestamp(from_utc_timestamp(df("date"), "GMT+01:00")) as "from_utc",
unix_timestamp(to_utc_timestamp(df("date"), "GMT+01:00")) as "to_utc").show(1,
false)
// +----------+----------+----------+
// |date |from_utc |to_utc |
// +----------+----------+----------+
// |1500000000|1500003600|1499996400|
// +----------+----------+----------+
{code}
So if interpret correctly {{from_utc_timestamp}}, took {{02:40 UTC}}
interpreted it as {{03:40 GMT+1}} (same timestamp) and transformed it to
{{03:40 UTC}}. However the description of {{from_utc_timestamp}} says
bq. Given a timestamp, which corresponds to a certain time of day in UTC,
returns another timestamp that corresponds to the same time of day in the given
timezone.
I would have expected then that the function takes {{02:40 UTC}} and return
{{02:40 GMT+1 = 01:40 UTC}}. In fact the descriptions of {{from_utc_timestamp}}
and {{to_utc_timestamp}} seem inverted.
I am interpreting this right?
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