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https://issues.apache.org/jira/browse/SPARK-15613?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Davies Liu reassigned SPARK-15613:
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    Assignee: Davies Liu

> Incorrect days to millis conversion 
> ------------------------------------
>
>                 Key: SPARK-15613
>                 URL: https://issues.apache.org/jira/browse/SPARK-15613
>             Project: Spark
>          Issue Type: Sub-task
>          Components: SQL
>    Affects Versions: 1.6.0, 2.0.0
>         Environment: java version "1.8.0_91"
>            Reporter: Dmitry Bushev
>            Assignee: Davies Liu
>            Priority: Critical
>
> There is an issue with {{DateTimeUtils.daysToMillis}} implementation. It  
> affects {{DateTimeUtils.toJavaDate}} and ultimately CatalystTypeConverter, 
> i.e the conversion of date stored as {{Int}} days from epoch in InternalRow 
> to {{java.sql.Date}} of Row returned to user.
>  
> The issue can be reproduced with this test (all the following tests are in my 
> defalut timezone Europe/Moscow):
> {code}
> $ sbt -Duser.timezone=Europe/Moscow catalyst/console
> scala> java.util.Calendar.getInstance().getTimeZone
> res0: java.util.TimeZone = 
> sun.util.calendar.ZoneInfo[id="Europe/Moscow",offset=10800000,dstSavings=0,useDaylight=false,transitions=79,lastRule=null]
> scala> import org.apache.spark.sql.catalyst.util.DateTimeUtils._
> import org.apache.spark.sql.catalyst.util.DateTimeUtils._
> scala> for (days <- 0 to 20000 if millisToDays(daysToMillis(days)) != days) 
> yield days
> res23: scala.collection.immutable.IndexedSeq[Int] = Vector(4108, 4473, 4838, 
> 5204, 5568, 5932, 6296, 6660, 7024, 7388, 8053, 8487, 8851, 9215, 9586, 9950, 
> 10314, 10678, 11042, 11406, 11777, 12141, 12505, 12869, 13233, 13597, 13968, 
> 14332, 14696, 15060)
> {code}
> For example, for {{4108}} day of epoch, the correct date should be 
> {{1981-04-01}}
> {code}
> scala> DateTimeUtils.toJavaDate(4107)
> res25: java.sql.Date = 1981-03-31
> scala> DateTimeUtils.toJavaDate(4108)
> res26: java.sql.Date = 1981-03-31
> scala> DateTimeUtils.toJavaDate(4109)
> res27: java.sql.Date = 1981-04-02
> {code}
> There was previous unsuccessful attempt to work around the problem in 
> SPARK-11415. It seems that issue involves flaws in java date implementation 
> and I don't see how it can be fixed without third-party libraries.
> I was not able to identify the library of choice for Spark. The following 
> implementation uses [JSR-310|http://www.threeten.org/]
> {code}
> def millisToDays(millisUtc: Long): SQLDate = {
>   val instant = Instant.ofEpochMilli(millisUtc)
>   val zonedDateTime = instant.atZone(ZoneId.systemDefault)
>   zonedDateTime.toLocalDate.toEpochDay.toInt
> }
> def daysToMillis(days: SQLDate): Long = {
>   val localDate = LocalDate.ofEpochDay(days)
>   val zonedDateTime = localDate.atStartOfDay(ZoneId.systemDefault)
>   zonedDateTime.toInstant.toEpochMilli
> }
> {code}
> that produces correct results:
> {code}
> scala> for (days <- 0 to 20000 if millisToDays(daysToMillis(days)) != days) 
> yield days
> res37: scala.collection.immutable.IndexedSeq[Int] = Vector()
> scala> new java.sql.Date(daysToMillis(4108))
> res36: java.sql.Date = 1981-04-01
> {code}



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