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new be5dfcd [SPARK-31402][SQL][FOLLOWUP] Refine code comments in
RebaseDateTime
be5dfcd is described below
commit be5dfcd2f2e42976db65cf2306371f0e7a74d4cc
Author: Wenchen Fan <wenc...@databricks.com>
AuthorDate: Tue Apr 14 08:06:55 2020 +0000
[SPARK-31402][SQL][FOLLOWUP] Refine code comments in RebaseDateTime
### What changes were proposed in this pull request?
Refine the code comments of days rebasing, to be consistent with the micros
rebasing. i.e. one method is the actual implementation and the other variant is
the optimized version.
### Why are the changes needed?
improve code comments
### Does this PR introduce any user-facing change?
No
### How was this patch tested?
N/A
Closes #28199 from cloud-fan/comment.
Authored-by: Wenchen Fan <wenc...@databricks.com>
Signed-off-by: Wenchen Fan <wenc...@databricks.com>
(cherry picked from commit 6b88d136deb99afd9363b208fd6fe5684fe8c3b8)
Signed-off-by: Wenchen Fan <wenc...@databricks.com>
---
.../spark/sql/catalyst/util/RebaseDateTime.scala | 62 +++++++++-------------
1 file changed, 26 insertions(+), 36 deletions(-)
diff --git
a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/RebaseDateTime.scala
b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/RebaseDateTime.scala
index f4a98cf..50b552e 100644
---
a/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/RebaseDateTime.scala
+++
b/sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/RebaseDateTime.scala
@@ -64,8 +64,7 @@ object RebaseDateTime {
// The sorted days in Julian calendar when difference in days between Julian
and
// Proleptic Gregorian calendars was changed.
// The starting point is the `0001-01-01` (-719164 days since the epoch in
- // Julian calendar). All dates before the staring point have the same
difference
- // of 2 days in Julian and Proleptic Gregorian calendars.
+ // Julian calendar). This array is not applicable for dates before the
staring point.
// Rebasing switch days and diffs `julianGregDiffSwitchDay` and
`julianGregDiffs`
// was generated by the `localRebaseJulianToGregorianDays` function.
private val julianGregDiffSwitchDay = Array(
@@ -80,6 +79,15 @@ object RebaseDateTime {
* calendar, interprets the result as a local date in Proleptic Gregorian
calendar, and takes the
* number of days since the epoch from the Gregorian 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:
+ * Julian calendar: 1582-01-01 -> -141704
+ * Proleptic Gregorian calendar: 1582-01-01 -> -141714
+ * The code below converts -141704 to -141714.
+ *
* @param days The number of days since the epoch in Julian calendar. It can
be negative.
* @return The rebased number of days in Gregorian calendar.
*/
@@ -105,22 +113,9 @@ object RebaseDateTime {
}
/**
- * For dates of Before Common Era, the function converts the given number of
days since the epoch
- * day 1970-01-01 to a local date in Julian calendar, interprets the result
as a local date in
- * Proleptic Gregorian calendar, and takes the number of days since the
epoch from the Gregorian
- * local date.
- *
- * For dates of Common Era, the function performs rebasing via the
pre-calculated array of diffs
- * between Julian and Proleptic Gregorian calendars.
- *
- * 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:
- * Julian calendar: 1582-01-01 -> -141704
- * Proleptic Gregorian calendar: 1582-01-01 -> -141714
- * The code below converts -141704 to -141714.
+ * An optimized version of [[localRebaseJulianToGregorianDays(Int)]]. This
method leverages the
+ * pre-calculated rebasing array to save calculation. For dates of Before
Common Era, the
+ * function falls back to the regular unoptimized version.
*
* @param days The number of days since the epoch in Julian calendar. It can
be negative.
* @return The rebased number of days in Gregorian calendar.
@@ -140,8 +135,7 @@ object RebaseDateTime {
// The sorted days in Proleptic Gregorian calendar when difference in days
between
// Proleptic Gregorian and Julian was changed.
// The starting point is the `0001-01-01` (-719162 days since the epoch in
- // Proleptic Gregorian calendar). All dates before the staring point have
the same
- // difference of -2 days in Proleptic Gregorian and Julian calendars.
+ // Proleptic Gregorian calendar). This array is not applicable for dates
before the staring point.
// Rebasing switch days and diffs `gregJulianDiffSwitchDay` and
`gregJulianDiffs`
// was generated by the `localRebaseGregorianToJulianDays` function.
private val gregJulianDiffSwitchDay = Array(
@@ -157,6 +151,15 @@ object RebaseDateTime {
* Gregorian calendar, interprets the result as a local date in Julian
calendar, and takes 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 in Proleptic Gregorian
calendar.
* It can be negative.
* @return The rebased number of days in Julian calendar.
@@ -174,22 +177,9 @@ object RebaseDateTime {
}
/**
- * For dates of Before Common Era, 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 takes the number of days since the epoch
from the Julian
- * local date.
- *
- * For dates of Common Era, the function performs rebasing via the
pre-calculated array of diffs
- * between Proleptic Gregorian and Julian calendars.
- *
- * 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.
+ * An optimized version of [[localRebaseGregorianToJulianDays(Int)]]. This
method leverages the
+ * pre-calculated rebasing array to save calculation. For dates of Before
Common Era, the
+ * function falls back to the regular unoptimized version.
*
* @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.
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