There is another feature missing for CalendarInterval, which is related
to comparability: measure the length of an interval.
Would be nice if you could access the length of an interval, than you
could compute something like this:
|Seq((Timestamp.valueOf("2020-02-01 12:00:00"),
Timestamp.valueOf("2020-02-01 13:30:25"))) .toDF("start", "end")
.withColumn("interval", $"end" - $"start") .withColumn("interval [h]",
*INTERVAL LENGTH IN HOURS*) .withColumn("rate [€/h]", lit(1.45))
.withColumn("price [€]", $"interval [h]" * $"rate [€/h]") .show(false)
+-------------------+-------------------+-----------------------------+------------------+----------+------------------+
|start |end |interval |interval [h] |rate [€/h]|price [€] |
+-------------------+-------------------+-----------------------------+------------------+----------+------------------+
|2020-02-01 12:00:00|2020-02-01 13:30:25|1 hours 30 minutes 25
seconds|1.5069444444444444|1.45 |2.1850694444444443|
+-------------------+-------------------+-----------------------------+------------------+----------+------------------+
|
The length of an interval can be measured by dividing it with the length
of your measuring unit, e.g. "1 hour":
||$"interval" / lit("1 hour").cast(CalendarIntervalType)| |
Which brings us to CalendarInterval division:
https://github.com/apache/spark/pull/27805
Enrico
Am 11.02.20 um 21:09 schrieb Enrico Minack:
I compute the difference of two timestamps and compare them with a
constant interval:
Seq(("2019-01-02 12:00:00", "2019-01-02 13:30:00"))
.toDF("start", "end")
.select($"start".cast(TimestampType), $"end".cast(TimestampType))
.select($"start", $"end", ($"end" - $"start").as("diff"))
.where($"diff" < lit("INTERVAL 2 HOUR").cast(CalendarIntervalType))
.show
Coming from timestamps, the interval should have correct hours
(millisecond component), so comparing it with the "right kinds of
intervals" should always be correct.
Enrico
Am 11.02.20 um 17:06 schrieb Wenchen Fan:
What's your use case to compare intervals? It's tricky in Spark as
there is only one interval type and you can't really compare one
month with 30 days.
On Wed, Feb 12, 2020 at 12:01 AM Enrico Minack
<m...@enrico.minack.dev <mailto:m...@enrico.minack.dev>> wrote:
Hi Devs,
I would like to know what is the current roadmap of making
CalendarInterval comparable and orderable again (SPARK-29679,
SPARK-29385, #26337).
With #27262, this got reverted but SPARK-30551 does not mention
how to
go forward in this matter. I have found SPARK-28494, but this
seems to
be stale.
While I find it useful to compare such intervals, I cannot find a
way to
work around the missing comparability. Is there a way to get,
e.g. the
seconds that an interval represents to be able to compare
intervals? In
org.apache.spark.sql.catalyst.util.IntervalUtils there are
methods like
getEpoch or getDuration, which I cannot see are exposed to SQL or
in the
org.apache.spark.sql.functions package.
Thanks for the insights,
Enrico
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