sjwiesman commented on a change in pull request #13384:
URL: https://github.com/apache/flink/pull/13384#discussion_r489576296
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File path: docs/dev/libs/state_processor_api.md
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@@ -345,6 +345,44 @@ Along with reading registered state values, each key has
access to a `Context` w
{% panel **Note:** When using a `KeyedStateReaderFunction`, all state
descriptors must be registered eagerly inside of open. Any attempt to call a
`RuntimeContext#get*State` will result in a `RuntimeException`. %}
+### Window State
+
+The state processor api supports reading state from a [window operator]({{
site.baseurl }}/dev/stream/operators/windows.html).
+This includes both time based windows along with other types, pre-aggregation,
non-aggregated, and windows with evictors.
+
+<div class="codetabs" markdown="1">
+<div data-lang="java" markdown="1">
+{% highlight java %}
+
+ExecutionEnvironment batchEnv = ExecutionEnvironment.getExecutionEnvironment();
+ExistingSavepoint savepoint = Savepoint.load(batchEnv,
"hdfs://checkpoint-dir", new MemoryStateBackend());
+
+int count = savepoint
+ // The timeWindow method supports reading from any type of time based
window, including but not limited to
+ // Tumbling, Sliding, and Session windows for both event time and
processing time.
+ .timeWindow()
+ .reduce(uid, new ReduceSum(), Types.INT, Types.INT)
+ .count();
Review comment:
`count` is a dataset feature. Will remove.
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