Github user hvanhovell commented on a diff in the pull request:
https://github.com/apache/spark/pull/12147#discussion_r58429851
--- Diff:
sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/windowExpressions.scala
---
@@ -262,19 +270,82 @@ object SpecifiedWindowFrame {
*/
def defaultWindowFrame(
hasOrderSpecification: Boolean,
- acceptWindowFrame: Boolean): SpecifiedWindowFrame = {
+ acceptWindowFrame: Boolean,
+ excludeSpec: ExcludeClause = ExcludeClause.defaultExclude):
SpecifiedWindowFrame = {
if (hasOrderSpecification && acceptWindowFrame) {
// If order spec is defined and the window function supports user
specified window frames,
// the default frame is RANGE BETWEEN UNBOUNDED PRECEDING AND
CURRENT ROW.
- SpecifiedWindowFrame(RangeFrame, UnboundedPreceding, CurrentRow)
+ SpecifiedWindowFrame(RangeFrame, UnboundedPreceding, CurrentRow,
excludeSpec)
} else {
// Otherwise, the default frame is
// ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING.
- SpecifiedWindowFrame(RowFrame, UnboundedPreceding,
UnboundedFollowing)
+ SpecifiedWindowFrame(RowFrame, UnboundedPreceding,
UnboundedFollowing, excludeSpec)
}
}
}
+/**
+ * The trait used to represent an Exclude type .
+ */
+sealed trait ExcludeType
+
+/**
+ * Represents the type of Excluding Current Row
+ */
+case object ExcludeCurrentRow extends ExcludeType
+
+/**
+ * Specifies excluding the current row and all rows that are tied with it.
+ * Ties occur when there is a match on the order-by column or columns
+ */
+case object ExcludeGroup extends ExcludeType
+
+/**
+ * Specifies excluding all rows that are tied with the current row (peer
rows),
+ * but retaining the current row.
+ */
+case object ExcludeTies extends ExcludeType
+
+/**
+ * Specifies not excluding any rows. This value is the default if you
specify no exclusion.
+ */
+case object ExcludeNoOthers extends ExcludeType
+
+/**
+ * Exclude clause within window framing clause.
+ *
+ * 'EXCLUDE CURRENT ROW' means the current row for which the window
function is calculated
+ * is excluded from the current fame.
+ * 'EXCLUDE GROUP' means that the nearby rows that match the current row
with respect to
+ * the orderby expression together with the current row will be excluded
from the calculation
+ * 'EXCLUDE TIES' means that the nearby rows that match the current row
with respect to
+ * the orderby expression except the current row will be excluded from the
calculation
+ * 'EXCLUDE NO OTHERS' means not excluding any rows from the calculation.
This is the
+ * default behavior. Exclude types, GROUP and TIES, requires ORDER BY
clause in the window
+ * specification clause.
+ * For example, users want to exclude current row from a sliding range
framing:
+ * RANGE BETWEEN 2 PRECEDING AND 2 FOLLOWING EXCLUDE CURRENT ROW
+ * @param excludeType The type of exclusion as defined above
+ * @param valueOrdering The ordering operator that does the value
comparison between 2 rows
+ * @param toBeCompared The projection of the orderby expression from a row
+ *
+ */
+case class ExcludeClause (
--- End diff --
Do we need this class in this location? It seems like this is bound to its
implementation? Just passing ExcludeTypes should be fine for now.
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