[GitHub] [flink] alpinegizmo commented on a change in pull request #13510: [FLINK-13095][state-processor-api] Introduce window bootstrap writer for writing window operator state

[GitBox <gi...@apache.org>]

alpinegizmo commented on a change in pull request #13510:
URL: https://github.com/apache/flink/pull/13510#discussion_r498222828



##########
File path: docs/dev/libs/state_processor_api.md
##########
@@ -742,6 +740,56 @@ If a processing time timer is set but the state is not restored until after that
 
 <span class="label label-danger">Attention</span> If your bootstrap function creates timers, the state can only be restored using one of the [process]({{ site.baseurl }}/dev/stream/operators/process_function.html) type functions.
 
+### Window State
+
+The state processor api supports writing state for the [window operator]({{ site.baseurl }}/dev/stream/operators/windows.html).
+When writing window state, users specify the operator id, window assigner, evictor, optional trigger, and aggregation type.
+It is important the configurations on the bootstrap transformation match the configurations on the DataStream window.
+
+<div class="codetabs" markdown="1">
+<div data-lang="java" markdown="1">
+{% highlight java %}
+public class Account {
+    public int id;
+
+    public double amount;	
+
+    public long timestamp;
+}
+ 
+ExecutionEnvironment bEnv = ExecutionEnvironment.getExecutionEnvironment();
+
+DataSet<Account> accountDataSet = bEnv.fromCollection(accounts);
+
+BootstrapTransformation<Account> transformation = OperatorTransformation
+    .bootstrapWith(accountDataSet)
+    // When using event time windows, its important

Review comment:
       ```suggestion
       // When using event time windows, it is important
   ```

##########
File path: docs/dev/libs/state_processor_api.md
##########
@@ -742,6 +740,56 @@ If a processing time timer is set but the state is not restored until after that
 
 <span class="label label-danger">Attention</span> If your bootstrap function creates timers, the state can only be restored using one of the [process]({{ site.baseurl }}/dev/stream/operators/process_function.html) type functions.
 
+### Window State
+
+The state processor api supports writing state for the [window operator]({{ site.baseurl }}/dev/stream/operators/windows.html).
+When writing window state, users specify the operator id, window assigner, evictor, optional trigger, and aggregation type.
+It is important the configurations on the bootstrap transformation match the configurations on the DataStream window.
+
+<div class="codetabs" markdown="1">
+<div data-lang="java" markdown="1">
+{% highlight java %}
+public class Account {
+    public int id;
+
+    public double amount;	
+
+    public long timestamp;
+}
+ 
+ExecutionEnvironment bEnv = ExecutionEnvironment.getExecutionEnvironment();
+
+DataSet<Account> accountDataSet = bEnv.fromCollection(accounts);
+
+BootstrapTransformation<Account> transformation = OperatorTransformation
+    .bootstrapWith(accountDataSet)
+    // When using event time windows, its important
+    // to assign timestamps to each record.
+    .assignTimestamps(account -> account.timestamp)
+    .keyBy(acc -> acc.id)
+    .window(TumblingEventTimeWindows.of)
+    .reduce((left, right) -> left + right);
+{% endhighlight %}
+</div>
+<div data-lang="java" markdown="1">
+{% highlight scala %}
+case class Account(id: Int, amount: Double, timestamp: Long)
+ 
+val bEnv = ExecutionEnvironment.getExecutionEnvironment();
+val accountDataSet = bEnv.fromCollection(accounts);
+
+val transformation = OperatorTransformation
+    .bootstrapWith(accountDataSet)
+    // When using event time windows, its important
+    // to assign timestamps to each record.
+    .assignTimestamps(account -> account.timestamp)
+    .keyBy(acc -> acc.id)
+    .window(TumblingEventTimeWindows.of)
+    .reduce((left, right) -> left + right)

Review comment:
       This doesn't look like code that would actually compile.




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