org.apache.flink.table.api

Interface WindowGroupedTable

@PublicEvolving
public interface WindowGroupedTable

A table that has been windowed and grouped for GroupWindows.

Method Summary

Modifier and Type	Method and Description
AggregatedTable	aggregate(Expression aggregateFunction) Performs an aggregate operation on a window grouped table.
FlatAggregateTable	flatAggregate(Expression tableAggregateFunction) Performs a flatAggregate operation on a window grouped table.
Table	select(Expression... fields) Performs a selection operation on a window grouped table.

Method Detail

select

Table select(Expression... fields)

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:

 windowGroupedTable.select($("key"), $("window").start(), $("value").avg().as("valavg"));
 

Scala Example:

 windowGroupedTable.select('key, 'window.start, 'value.avg as 'valavg)
 

aggregate

AggregatedTable aggregate(Expression aggregateFunction)

Performs an aggregate operation on a window grouped table. You have to close the aggregate(Expression) with a select statement. The output will be flattened if the output type is a composite type.

Example:

 windowGroupedTable.aggregate(call(MyAggregateFunction.class, $("a"), $("b")).as("x", "y", "z"))
   .select($("key"), $("window").start(), $("x"), $("y"), $("z"));
 

Scala Example:

 val aggFunc = new MyAggregateFunction
 windowGroupedTable
   .aggregate(aggFunc('a, 'b) as ('x, 'y, 'z))
   .select('key, 'window.start, 'x, 'y, 'z)
 

flatAggregate

FlatAggregateTable flatAggregate(Expression tableAggregateFunction)

Performs a flatAggregate operation on a window grouped table. FlatAggregate takes a TableAggregateFunction which returns multiple rows. Use a selection after flatAggregate.

Example:

 windowGroupedTable.flatAggregate(call(MyTableAggregateFunction.class, $("a"), $("b")).as("x", "y", "z"))
   .select($("key"), $("window").start(), $("x"), $("y"), $("z"));
 

Scala Example:

 val tableAggFunc = new MyTableAggregateFunction
 windowGroupedTable
   .flatAggregate(tableAggFunc('a, 'b) as ('x, 'y, 'z))
   .select('key, 'window.start, 'x, 'y, 'z)