twalthr commented on a change in pull request #7920: [FLINK-11844][table-api]
Simplify over window API classes and improve documentation
URL: https://github.com/apache/flink/pull/7920#discussion_r264118237
##########
File path:
flink-table/flink-table-planner/src/main/scala/org/apache/flink/table/api/windows.scala
##########
@@ -20,90 +20,180 @@ package org.apache.flink.table.api
import org.apache.flink.table.expressions._
import org.apache.flink.table.plan.logical._
-import org.apache.flink.table.typeutils.{RowIntervalTypeInfo,
TimeIntervalTypeInfo}
-import org.apache.flink.table.api.scala.{CURRENT_RANGE, CURRENT_ROW}
/**
- * Over window is similar to the traditional OVER SQL.
+ * A over-window specification.
+ *
+ * Similar to SQL, over window aggregates compute an aggregate for each input
row over a range
+ * of its neighboring rows.
+ */
+class OverWindow(
+ alias: Expression,
+ partitionBy: Seq[Expression],
+ orderBy: Expression,
+ preceding: Expression,
+ following: Option[Expression]) {
+
+ def getAlias: Expression = alias
+
+ def getPartitioning: Seq[Expression] = partitionBy
+
+ def getOrder: Expression = orderBy
+
+ def getPreceding: Expression = preceding
+
+ def getFollowing: Option[Expression] = following
+}
+
+//
------------------------------------------------------------------------------------------------
+// Over windows
+//
------------------------------------------------------------------------------------------------
+
+/**
+ * Partially defined over window with partitioning.
+ */
+class OverWindowPartitioned(partitionBy: Seq[Expression]) {
+
+ /**
+ * Specifies the time attribute on which rows are ordered.
+ *
+ * For streaming tables, reference a rowtime or proctime time attribute here
+ * to specify the time mode.
+ *
+ * For batch tables, refer to a timestamp or long attribute.
+ *
+ * @param orderByExpr field reference
+ * @return an over window with defined order
+ */
+ def orderBy(orderByExpr: String): OverWindowPartitionedOrdered = {
+ orderBy(ExpressionParser.parseExpression(orderByExpr))
+ }
+
+ /**
+ * Specifies the time attribute on which rows are ordered.
+ *
+ * For streaming tables, reference a rowtime or proctime time attribute here
+ * to specify the time mode.
+ *
+ * For batch tables, refer to a timestamp or long attribute.
+ *
+ * @param orderBy field reference
+ * @return an over window with defined order
+ */
+ def orderBy(orderBy: Expression): OverWindowPartitionedOrdered = {
+ new OverWindowPartitionedOrdered(partitionBy, orderBy)
+ }
+}
+
+/**
+ * Partially defined over window with (optional) partitioning and order.
*/
-case class OverWindow(
- private[flink] val alias: Expression,
- private[flink] val partitionBy: Seq[Expression],
- private[flink] val orderBy: Expression,
- private[flink] val preceding: Expression,
- private[flink] val following: Expression)
+class OverWindowPartitionedOrdered(partitionBy: Seq[Expression], orderBy:
Expression) {
+
+ /**
+ * Set the preceding offset (based on time or row-count intervals) for over
window.
+ *
+ * @param precedingExpr preceding offset relative to the current row.
+ * @return an over window with defined preceding
+ */
+ def preceding(precedingExpr: String): OverWindowPartitionedOrderedPreceding
= {
+ preceding(ExpressionParser.parseExpression(precedingExpr))
+ }
+
+ /**
+ * Set the preceding offset (based on time or row-count intervals) for over
window.
+ *
+ * @param preceding preceding offset relative to the current row.
+ * @return an over window with defined preceding
+ */
+ def preceding(preceding: Expression): OverWindowPartitionedOrderedPreceding
= {
+ new OverWindowPartitionedOrderedPreceding(partitionBy, orderBy, preceding)
+ }
+
+ /**
+ * Assigns an alias for this window that the following `select()` clause
can refer to.
+ *
+ * @param alias alias for this over window
+ * @return the fully defined over window
+ */
+ def as(alias: String): OverWindow =
as(ExpressionParser.parseExpression(alias))
+
+ /**
+ * Assigns an alias for this window that the following `select()` clause
can refer to.
+ *
+ * @param alias alias for this over window
+ * @return the fully defined over window
+ */
+ def as(alias: Expression): OverWindow = {
+ new OverWindow(alias, partitionBy, orderBy, UnboundedRange(), None)
+ }
+}
/**
- * A partially defined over window.
+ * Partially defined over window with (optional) partitioning, order, and
preceding.
*/
-class OverWindowWithPreceding(
+class OverWindowPartitionedOrderedPreceding(
private val partitionBy: Seq[Expression],
private val orderBy: Expression,
private val preceding: Expression) {
- private[flink] var following: Expression = _
+ private var optionalFollowing: Option[Expression] = None
/**
* Assigns an alias for this window that the following `select()` clause
can refer to.
*
* @param alias alias for this over window
- * @return over window
+ * @return the fully defined over window
*/
def as(alias: String): OverWindow =
as(ExpressionParser.parseExpression(alias))
/**
* Assigns an alias for this window that the following `select()` clause
can refer to.
*
* @param alias alias for this over window
- * @return over window
+ * @return the fully defined over window
*/
def as(alias: Expression): OverWindow = {
-
- // set following to CURRENT_ROW / CURRENT_RANGE if not defined
- if (null == following) {
- if (preceding.resultType.isInstanceOf[RowIntervalTypeInfo]) {
- following = CURRENT_ROW
- } else {
- following = CURRENT_RANGE
- }
- }
- OverWindow(alias, partitionBy, orderBy, preceding, following)
+ new OverWindow(alias, partitionBy, orderBy, preceding, optionalFollowing)
}
/**
* Set the following offset (based on time or row-count intervals) for over
window.
*
- * @param following following offset that relative to the current row.
- * @return this over window
+ * @param followingExpr following offset that relative to the current row.
+ * @return an over window with defined following
*/
- def following(following: String): OverWindowWithPreceding = {
- this.following(ExpressionParser.parseExpression(following))
+ def following(followingExpr: String): OverWindowPartitionedOrderedPreceding
= {
Review comment:
+1, my IDE was just complaining about the name duplicate but I solved this
issue by using `this.` again.
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