Github user tarekauel commented on a diff in the pull request:
https://github.com/apache/spark/pull/6981#discussion_r34318894
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/datetimeFunctions.scala
---
@@ -54,3 +60,313 @@ case class CurrentTimestamp() extends LeafExpression {
System.currentTimeMillis() * 1000L
}
}
+
+/**
+ * Abstract class for create time format expressions.
+ */
+abstract class TimeFormatExpression extends UnaryExpression with
ExpectsInputTypes {
+ self: Product =>
+
+ protected val factorToMilli: Int
+
+ protected val cntPerInterval: Int
+
+ override def inputTypes: Seq[AbstractDataType] = Seq(TimestampType)
+
+ override def dataType: DataType = IntegerType
+
+ override protected def nullSafeEval(timestamp: Any): Any = {
+ val time = timestamp.asInstanceOf[Long] / 1000
+ val longTime: Long = time + TimeZone.getDefault.getOffset(time)
+ ((longTime / factorToMilli) % cntPerInterval).toInt
+ }
+
+ override def genCode(ctx: CodeGenContext, ev: GeneratedExpressionCode):
String = {
+ val tz = classOf[TimeZone].getName
+ defineCodeGen(ctx, ev, (c) =>
+ s"""(${ctx.javaType(dataType)})
+ ((($c / 1000) + $tz.getDefault().getOffset($c / 1000))
+ / $factorToMilli % $cntPerInterval)"""
+ )
+ }
+}
+
+case class Hour(child: Expression) extends TimeFormatExpression {
+
+ override protected val factorToMilli: Int = 1000 * 3600
+
+ override protected val cntPerInterval: Int = 24
+}
+
+case class Minute(child: Expression) extends TimeFormatExpression {
--- End diff --
I thought that Daylight saving time is just a part of it. The given long
value depends on the local time difference, doesn't it. In order to calculate
the correct value for `Hour` and `Minute` we need the long time value as of
UTC, don't we. For seconds it doesn't matter, but there are time differences
like 4:30. So `Minutes` depends on the timezone as well. Maybe I'm wrong and I
just didn't got your idea, yet.
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