curcur commented on a change in pull request #18431:
URL: https://github.com/apache/flink/pull/18431#discussion_r794202114



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File path: docs/content/docs/ops/state/state_backends.md
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@@ -325,6 +325,129 @@ public class MyOptionsFactory implements 
ConfigurableRocksDBOptionsFactory {
 
 {{< top >}}
 
+## Enabling Changelog
+
+// todo: Chinese version of all changed docs
+
+// todo: mention in [large state tuning]({{< ref 
"docs/ops/state/large_state_tuning" >}})? or 1.16?
+
+{{< hint warning >}} This feature is in experimental status. {{< /hint >}}
+
+{{< hint warning >}} Enabling Changelog may have a negative performance impact 
on your application (see below). {{< /hint >}}
+
+### Introduction
+
+Changelog is a feature that aims to decrease checkpointing time and, 
therefore, end-to-end latency in exactly-once mode.
+
+Most commonly, checkpoint duration is affected by:
+
+1. Barrier travel time and alignment, addressed by
+   [Unaligned checkpoints]({{< ref 
"docs/ops/state/checkpointing_under_backpressure#unaligned-checkpoints" >}})
+   and [Buffer debloating]({{< ref 
"docs/ops/state/checkpointing_under_backpressure#buffer-debloating" >}})
+2. Snapshot creation time (so-called synchronous phase), addressed by 
asynchronous snapshots

Review comment:
       **Without Changelog:**
   Sync phase: flush in-mem data -> disk, prepare what-ssts to upload
   
   **With Changelog:**
   Sync phase: prepare state-changes to upload
   
   From the differences above, I can not infer what async snapshots refer to 
and can not see what problem the "async snapshots are addressed"? Or if I 
misunderstand the above process?
   
   




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