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https://issues.apache.org/jira/browse/FLINK-6228?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15977653#comment-15977653
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ASF GitHub Bot commented on FLINK-6228:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3743#discussion_r112482490
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/windows.scala
---
@@ -22,6 +22,126 @@ import org.apache.flink.table.expressions.{Expression,
ExpressionParser}
import org.apache.flink.table.plan.logical._
/**
+ * An over window specification.
+ *
+ * Over window is similar to the traditional OVER SQL.
+ */
+class OverWindow {
+
+ private[flink] var alias: Expression = _
+ private[flink] var partitionBy: Seq[Expression] = Seq[Expression]()
+ private[flink] var orderBy: Expression = _
+ private[flink] var preceding: Expression = _
+ private[flink] var following: Expression = null
+
+ /**
+ * Assigns an alias for this window that the following `select()`
clause can refer to.
+ *
+ * @param alias alias for this over window
+ * @return this 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 this over window
+ */
+ def as(alias: Expression): OverWindow = {
--- End diff --
I think it would be good if we could enforce the alias.
This could be done by first build a window which is not of type
`OverWindow` and letting `as()` return the complete `OverWindow`
> Integrating the OVER windows in the Table API
> ---------------------------------------------
>
> Key: FLINK-6228
> URL: https://issues.apache.org/jira/browse/FLINK-6228
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Reporter: sunjincheng
> Assignee: sunjincheng
>
> Syntax:
> {code}
> table
> .overWindows(
> (Rows|Range [ partitionBy value_expression , ... [ n ]] [ orderBy
> order_by_expression]
> (preceding
> UNBOUNDED|value_specification.(rows|milli|second|minute|hour|day|month|year)|CURRENTROW)
> [following
> UNBOUNDED|value_specification.(rows|milli|second|minute|hour|day|month|year)|CURRENTROW]
> as alias,...[n])
> )
> .select( [col1,...[n]], (agg(col1) OVER overWindowAlias, … [n])
> {code}
> Implement restrictions:
> * All OVER clauses in the same SELECT clause must be exactly the same.
> * The PARTITION BY clause is optional (no partitioning results in single
> threaded execution).
> * The ORDER BY Before the
> [FLINK-5884|https://issues.apache.org/jira/browse/FLINK-5884] implementation
> orderBy may only have ‘rowtime/’proctime(for stream)/‘specific-time-field(for
> batch).
> * FOLLOWING is not supported.
> User interface design document [See |
> https://docs.google.com/document/d/13Z-Ovx3jwtmzkSweJyGkMy751BouhuJ29Y1CTNZt2DI/edit#]
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