Github user HyukjinKwon commented on a diff in the pull request:
https://github.com/apache/spark/pull/20787#discussion_r186277122
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/datetimeExpressions.scala
---
@@ -1194,13 +1194,21 @@ case class AddMonths(startDate: Expression,
numMonths: Expression)
}
/**
- * Returns number of months between dates date1 and date2.
+ * Returns number of months between dates `date1` and `date2`.
+ * If `date1` is later than `date2`, then the result is positive.
+ * If `date1` and `date2` are on the same day of month, or both
+ * are the last day of month, time of day will be ignored. Otherwise, the
+ * difference is calculated based on 31 days per month, and rounded to
+ * 8 digits unless roundOff=false.
*/
// scalastyle:off line.size.limit
@ExpressionDescription(
usage = """
- _FUNC_(timestamp1, timestamp2[, roundOff]) - Returns number of months
between `timestamp1` and `timestamp2`.
- The result is rounded to 8 decimal places by default. Set
roundOff=false otherwise."""",
+ _FUNC_(date1, date2) - If `date1` is later than `date2`, then the
result
--- End diff --
wait .. why did you change ` _FUNC_(timestamp1, timestamp2[, roundOff])`??
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