dongjoon-hyun commented on a change in pull request #26034: [SPARK-29364][SQL]
Return an interval from date subtract according to SQL standard
URL: https://github.com/apache/spark/pull/26034#discussion_r331763162
##########
File path:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/datetimeExpressions.scala
##########
@@ -1672,33 +1673,59 @@ case class TruncTimestamp(
}
/**
- * Returns the number of days from startDate to endDate.
+ * Returns the number of days from startDate to endDate or an interval between
the dates.
*/
+// scalastyle:off line.size.limit line.contains.tab
@ExpressionDescription(
- usage = "_FUNC_(endDate, startDate) - Returns the number of days from
`startDate` to `endDate`.",
+ usage = "_FUNC_(endDate, startDate) - Returns the number of days from
`startDate` to `endDate`." +
+ "When `spark.sql.ansi.enabled` is set to `true` and `spark.sql.dialect` is
`Spark`, it returns " +
+ "an interval between `startDate` (inclusive) and `endDate` (exclusive).",
examples = """
Examples:
> SELECT _FUNC_('2009-07-31', '2009-07-30');
1
-
> SELECT _FUNC_('2009-07-30', '2009-07-31');
-1
+ > SET spark.sql.ansi.enabled=true;
+ spark.sql.ansi.enabled true
+ > SET spark.sql.dialect=Spark;
+ spark.sql.dialect Spark
+ > select _FUNC_(date'tomorrow', date'yesterday');
+ interval 2 days
""",
since = "1.5.0")
+// scalastyle:on line.size.limit line.contains.tab
case class DateDiff(endDate: Expression, startDate: Expression)
extends BinaryExpression with ImplicitCastInputTypes {
override def left: Expression = endDate
override def right: Expression = startDate
override def inputTypes: Seq[AbstractDataType] = Seq(DateType, DateType)
- override def dataType: DataType = IntegerType
+ private val returnInterval: Boolean = {
+ val isSparkDialect = SQLConf.get.getConf(DIALECT) ==
Dialect.SPARK.toString()
+ SQLConf.get.ansiEnabled && isSparkDialect
Review comment:
Maybe, one-liner `SQLConf.get.ansiEnabled && SQLConf.get.getConf(DIALECT) ==
Dialect.POSTGRESQL.toString` is enough. Please note that I suggested
`Dialect.POSTGRESQL`.
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