curcur commented on a change in pull request #18431:
URL: https://github.com/apache/flink/pull/18431#discussion_r791313073
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File path: docs/content/docs/ops/state/state_backends.md
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@@ -325,6 +325,126 @@ 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 >}} The 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
+3. Snapshot upload time (asynchronous phase)
+
+The latter (upload time) can be decreased by [Incremental checkpoints]({{< ref
"#incremental-checkpoints" >}}). However,
+even with Incremental checkpoints, large deployments tend to have at least one
task in every checkpoint that uploads a
+lot of data (e.g. after compaction).
Review comment:
I am not asking to explain the entire different compaction algorithms,
but since you mentioned "at least one task in every checkpoint that uploads a
lot of data (e.g. after compaction)." You need to explain why.
That's what I mean by providing some context: what causes to upload a lot
data; that's compaction, then why compaction causes more data to upload... e.t.c
I do not think people can infer directly why compaction can cause more data
to upload until you explain at least a little bit of different level of
compaction e.t.c.
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