gaoyunhaii commented on a change in pull request #18797:
URL: https://github.com/apache/flink/pull/18797#discussion_r808637597
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File path: docs/content/docs/connectors/datastream/filesystem.md
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@@ -958,6 +958,73 @@ val sink = FileSink
{{< /tab >}}
{{< /tabs >}}
+### Compaction
+
+Since version 1.15 `FileSink` supports compaction of the `pending` files,
+which allows the application to have smaller checkpoint interval without
generating a lot of small files,
+especially when using the [bulk encoded formats]({{< ref
"docs/connectors/datastream/filesystem#bulk-encoded-formats" >}})
+that have to rolling on taking checkpoints.
+
+Compaction could be enabled with
+
+{{< tabs "enablecompaction" >}}
+{{< tab "Java" >}}
+```java
+
+FileSink<Integer> fileSink=
+ FileSink.forRowFormat(new Path(path),new SimpleStringEncoder<Integer>())
+ .enableCompact(
+ FileCompactStrategy.Builder.newBuilder()
+ .setSizeThreshold(1024)
+ .enableCompactionOnCheckpoint(5)
+ .build(),
+ new RecordWiseFileCompactor<>(
+ new DecoderBasedReader.Factory<>(SimpleStringDecoder::new)))
+ .build();
+
+```
+{{< /tab >}}
+{{< tab "Scala" >}}
+```scala
+
+val fileSink: FileSink[Integer] =
+ FileSink.forRowFormat(new Path(path), new SimpleStringEncoder[Integer]())
+ .enableCompact(
+ FileCompactStrategy.Builder.newBuilder()
+ .setSizeThreshold(1024)
+ .enableCompactionOnCheckpoint(5)
+ .build(),
+ new RecordWiseFileCompactor(
+ new DecoderBasedReader.Factory(() => new SimpleStringDecoder)))
+ .build()
+
+```
+{{< /tab >}}
+{{< /tabs >}}
+
+Once enabled, the compaction happens between the files become `pending` and
get committed. The pending files will
+be first committed to temporary files whose path starts with `.`. Then these
files will be compacted according to
+the strategy by the compactor specified by the users, and the new compacted
pending files will be generated.
+Then these pending files will be emitted to the committer to be committed to
the formal files. After that, the source files will be removed.
+
+When enabling compaction, you need to specify the {{< javadoc
file="org/apache/flink/connector/file/sink/compactor/FileCompactStrategy.html"
name="FileCompactStrategy">}}
+and the {{< javadoc
file="org/apache/flink/connector/file/sink/compactor/FileCompactor.html"
name="FileCompactor">}}.
+
+The {{< javadoc
file="org/apache/flink/connector/file/sink/compactor/FileCompactStrategy.html"
name="FileCompactStrategy">}} specifies
+when and which files get compacted. Currently, there are two parallel
conditions: the target file size and the number of checkpoints get passed.
+Once the total size of the cached files has reached the size threshold or the
number of checkpoints since the last compaction has reached the specified
number,
+the cached files will be scheduled to compact.
+
+The {{< javadoc
file="org/apache/flink/connector/file/sink/compactor/FileCompactor.html"
name="FileCompactor">}} specifies how to compact
+the give list of `Path` and write the result to {{< javadoc
file="org/apache/flink/connector/file/sink/filesystem/CompactingFileWriter.html"
name="CompactingFileWriter">}}. It could be classified into two types
according to the type of the give `CompactingFileWriter`:
Review comment:
The link to CompactingFileWriter seems not right. Also the same with the
Chinese version
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