[GitHub] hequn8128 commented on a change in pull request #7188: [FLINK-10473][State TTL] TTL state incremental cleanup for heap backend

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hequn8128 commented on a change in pull request #7188: [FLINK-10473][State TTL] TTL state incremental cleanup for heap backend
URL: https://github.com/apache/flink/pull/7188#discussion_r243473440
 
 

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 File path: docs/dev/stream/state/state.md
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 @@ -394,6 +396,47 @@ val ttlConfig = StateTtlConfig
 
 This option is not applicable for the incremental checkpointing in the RocksDB state backend.
 
+##### Incremental cleanup
+
+Another option is to trigger cleanup of some state entries incrementally.
+The trigger can be a callback from each state access or/and each record processing.
+If this cleanup strategy is active for certain state,
+The storage backend keeps a lazy global iterator for this state over all its entries.
+Every time incremental cleanup is triggered, the iterator is advanced.
+The traversed state entries are checked and expired ones are cleaned up.
+
+This feature can be activated in `StateTtlConfig`:
+
+<div class="codetabs" markdown="1">
+<div data-lang="java" markdown="1">
+{% highlight java %}
+import org.apache.flink.api.common.state.StateTtlConfig;
+ StateTtlConfig ttlConfig = StateTtlConfig
+    .newBuilder(Time.seconds(1))
+    .cleanupInRocksdbCompactFilter()
+    .build();
+{% endhighlight %}
+</div>
+ <div data-lang="scala" markdown="1">
+{% highlight scala %}
+import org.apache.flink.api.common.state.StateTtlConfig
+ val ttlConfig = StateTtlCon fig
 
 Review comment:
   Remove the blank

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