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Posted to issues@spark.apache.org by "Apache Spark (JIRA)" <ji...@apache.org> on 2017/09/19 10:27:00 UTC
[jira] [Assigned] (SPARK-22049) Confusing behavior of
from_utc_timestamp and to_utc_timestamp
[ https://issues.apache.org/jira/browse/SPARK-22049?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Apache Spark reassigned SPARK-22049:
------------------------------------
Assignee: (was: Apache Spark)
> 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: Improvement
> Components: Documentation, 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 then expected that the function take {{02:40 UTC}} and return {{02:40 GMT+1 = 01:40 UTC}}. In fact, I think the descriptions of {{from_utc_timestamp}} and {{to_utc_timestamp}} are inverted.
> I am interpreting this right?
> Thanks in advance
> Felipe
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