cloud-fan commented on a change in pull request #28166:
[SPARK-31359][DOC][followup] improve code comments in RebaseDateTime
URL: https://github.com/apache/spark/pull/28166#discussion_r406108658
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/RebaseDateTime.scala
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@@ -97,51 +105,26 @@ object RebaseDateTime {
-390750, -354226, -317702, -244653, -208129, -171605, -141427)
/**
- * Rebasing days since the epoch to store the same number of days
- * as by Spark 2.4 and earlier versions. Spark 3.0 switched to
- * Proleptic Gregorian calendar (see SPARK-26651), and as a consequence of
that,
- * this affects dates before 1582-10-15. Spark 2.4 and earlier versions use
- * Julian calendar for dates before 1582-10-15. So, the same local date may
- * be mapped to different number of days since the epoch in different
calendars.
+ * Converts the given number of days since the epoch day 1970-01-01 to a
local date in Proleptic
+ * Gregorian calendar, interprets the result as a local date in Julian
calendar, and take the
+ * number of days since the epoch from the Julian local date.
+ *
+ * This is used to guarantee backward compatibility, as Spark 2.4 and
earlier versions use
+ * Julian calendar for dates before 1582-10-15, while Spark 3.0 and later
use Proleptic Gregorian
+ * calendar. See SPARK-26651.
*
* For example:
* Proleptic Gregorian calendar: 1582-01-01 -> -141714
* Julian calendar: 1582-01-01 -> -141704
* The code below converts -141714 to -141704.
*
- * @param days The number of days since the epoch 1970-01-01. It can be
negative.
+ * @param days The number of days since the epoch in Gregorian calendar. It
can be negative.
* @return The rebased number of days since the epoch in Julian calendar.
*/
def rebaseGregorianToJulianDays(days: Int): Int = {
rebaseDays(gregJulianDiffSwitchDay, gregJulianDiffs, days)
}
- /**
- * Converts the given microseconds to a local date-time in UTC time zone in
Proleptic Gregorian
- * calendar, interprets the result as a local date-time in Julian calendar
in UTC time zone.
- * And takes microseconds since the epoch from the Julian timestamp.
- *
- * @param zoneId The time zone ID at which the rebasing should be performed.
- * @param micros The number of microseconds since the epoch
'1970-01-01T00:00:00Z'
- * in Proleptic Gregorian calendar. It can be negative.
- * @return The rebased microseconds since the epoch in Julian calendar.
- */
- private[sql] def rebaseGregorianToJulianMicros(zoneId: ZoneId, micros:
Long): Long = {
Review comment:
move it closer to its optimized version.
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