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https://issues.apache.org/jira/browse/FLINK-5386?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15830001#comment-15830001
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ASF GitHub Bot commented on FLINK-5386:
---------------------------------------
Github user fhueske commented on a diff in the pull request:
https://github.com/apache/flink/pull/3046#discussion_r96860442
--- Diff:
flink-libraries/flink-table/src/main/scala/org/apache/flink/table/api/table.scala
---
@@ -855,57 +858,45 @@ class GroupedTable(
val fieldExprs = ExpressionParser.parseExpressionList(fields)
select(fieldExprs: _*)
}
-
- /**
- * Groups the records of a table by assigning them to windows defined
by a time or row interval.
- *
- * For streaming tables of infinite size, grouping into windows is
required to define finite
- * groups on which group-based aggregates can be computed.
- *
- * For batch tables of finite size, windowing essentially provides
shortcuts for time-based
- * groupBy.
- *
- * @param groupWindow group-window that specifies how elements are
grouped.
- * @return A windowed table.
- */
- def window(groupWindow: GroupWindow): GroupWindowedTable = {
- new GroupWindowedTable(table, groupKey, groupWindow)
- }
}
-class GroupWindowedTable(
+class WindowGroupedTable(
private[flink] val table: Table,
private[flink] val groupKey: Seq[Expression],
- private[flink] val window: GroupWindow) {
+ private[flink] val window: Window) {
/**
- * Performs a selection operation on a windowed table. Similar to an
SQL SELECT statement.
+ * Performs a selection operation on a window grouped table. Similar to
an SQL SELECT statement.
* The field expressions can contain complex expressions and
aggregations.
*
* Example:
*
* {{{
- * groupWindowTable.select('key, 'window.start, 'value.avg + " The
average" as 'average)
+ * windowGroupedTable.select('key, 'window.start, 'value.avg + " The
average" as 'average)
* }}}
*/
def select(fields: Expression*): Table = {
+ // get group keys by removing window column
--- End diff --
window column -> window alias
> Refactoring Window Clause
> -------------------------
>
> Key: FLINK-5386
> URL: https://issues.apache.org/jira/browse/FLINK-5386
> Project: Flink
> Issue Type: Sub-task
> Components: Table API & SQL
> Reporter: sunjincheng
> Assignee: sunjincheng
>
> Similar to the SQL, window clause is defined "as" a symbol which is
> explicitly used in groupby/over. We are proposing to refactor the way to
> write groupby+window tableAPI as follows:
> {code}
> tab //Table('a,'b,'c)
> .window( Slide over 10.milli every 5.milli as 'w1as 'w1) // WindowedTable
> .groupBy('w1,'a,'b) // WindowGroupedTable
> .select('a,'b,c.count as 'mycount) // Table
> .window(Tumble over 5.milli on 'b as 'w2)
> .groupBy('w2)
> .select('a.count, 'w2.start, 'w2.end)
> {code}
> In this way, for row-window, we anyway need to define window clause as a
> symbol. This change will make the API of window and row-window consistent,
> example for row-window:
> {code}
> .window(RowXXXWindow as ‘x, RowYYYWindow as ‘y) // WindowedTable
> .select(‘a, ‘b.count over ‘x as ‘xcnt, ‘c.count over ‘y as ‘ycnt, ‘x.start,
> ‘x.end)
> {code}
> What do you think? [~fhueske] [~twalthr]
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