hequn8128 commented on a change in pull request #7209: [FLINK-10977][table] Add
UnBounded FlatAggregate operator to streaming Table API
URL: https://github.com/apache/flink/pull/7209#discussion_r246238933
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File path: docs/dev/table/tableApi.md
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@@ -550,6 +550,82 @@ val result = orders.distinct()
{% top %}
+### TableAggregations
+
+<div class="codetabs" markdown="1">
+<div data-lang="java" markdown="1">
+
+<table class="table table-bordered">
+ <thead>
+ <tr>
+ <th class="text-left" style="width: 20%">Operators</th>
+ <th class="text-center">Description</th>
+ </tr>
+ </thead>
+ <tbody>
+ <tr>
+ <td>
+ <strong>GroupBy TableAggregation</strong><br>
+ <span class="label label-primary">Streaming</span><br>
+ <span class="label label-info">Result Updating</span>
+ </td>
+ <td>
+ <p>Similar to a <b>GroupBy Aggregation</b>. Groups the rows on the
grouping keys with a following running table aggregation operator to aggregate
rows group-wise. The difference from an AggregateFunction is that
TableAggregateFunction may return 0 or more records for a group. You have to
close the "flatAggregate" with a select statement. And the select statement
does not support aggregate functions.</p>
+{% highlight java %}
+TableAggregateFunction tableAggFunc = new MyTableAggregateFunction();
+tableEnv.registerFunction("myTableAggFunc", tableAggFunc);
+Table orders = tableEnv.scan("Orders");
+Table result = orders
+ .groupBy("a")
+ .flatAggregate("myTableAggFunc(a, b, c)")
+ .select("_1 as a, _2 as b");
+{% endhighlight %}
+ <p><b>Note:</b> For streaming queries the required state to compute
the query result might grow infinitely depending on the type of aggregation and
the number of distinct grouping keys. Please provide a query configuration with
valid retention interval to prevent excessive state size. See <a
href="streaming/query_configuration.html">Query Configuration</a> for
details.</p>
+ </td>
+ </tr>
+
+ </tbody>
+</table>
+
+</div>
+<div data-lang="scala" markdown="1">
+
+<table class="table table-bordered">
+ <thead>
+ <tr>
+ <th class="text-left" style="width: 20%">Operators</th>
+ <th class="text-center">Description</th>
+ </tr>
+ </thead>
+ <tbody>
+
+ <tr>
+ <td>
+ <strong>GroupBy TableAggregation</strong><br>
+ <span class="label label-primary">Streaming</span><br>
+ <span class="label label-info">Result Updating</span>
+ </td>
+ <td>
+ <p>Similar to a <b>GroupBy Aggregation</b>. Groups the rows on the
grouping keys with a following running table aggregation operator to aggregate
rows group-wise. The difference from an AggregateFunction is that
TableAggregateFunction may return 0 or more records for a group. You have to
close the "flatAggregate" with a select statement. And the select statement
does not support aggregate functions.</p>
+{% highlight scala %}
+val tableAggFunc: TableAggregateFunction = new MyTableAggregateFunction
Review comment:
Oh, my fault. I think it should be `val tableAggFunc:
TableAggregateFunction[_, _] = new MyTableAggregateFunction`
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