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https://issues.apache.org/jira/browse/SPARK-15613?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15323386#comment-15323386
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Bo Meng commented on SPARK-15613:
---------------------------------
Does this only happen to 1.6? I have tried on the latest master and it does not
have this issue.
> 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
> Environment: java version "1.8.0_91"
> Reporter: Dmitry Bushev
>
> 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}
> 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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