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https://issues.apache.org/jira/browse/FLINK-8790?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16493631#comment-16493631
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ASF GitHub Bot commented on FLINK-8790:
---------------------------------------
Github user sihuazhou commented on a diff in the pull request:
https://github.com/apache/flink/pull/5582#discussion_r191453657
--- Diff:
flink-state-backends/flink-statebackend-rocksdb/src/main/java/org/apache/flink/contrib/streaming/state/RocksDBKeySerializationUtils.java
---
@@ -138,4 +138,12 @@ private static void writeVariableIntBytes(
value >>>= 8;
} while (value != 0);
}
+
+ public static byte[] serializeKeyGroup(int keyGroup, int
keyGroupPrefixBytes) {
+ byte[] startKeyGroupPrefixBytes = new byte[keyGroupPrefixBytes];
--- End diff --
Some info about the experiment I did:
- I set `ReadOptions::ignore_range_deletions = true` to speed up the read
performance, because we won't read any records that belong to the key-group we
have deleted.
- I only call the `deleteRange()` twice, because we will at most call it
twice in the recovery of the incremental checkpoint.
> Improve performance for recovery from incremental checkpoint
> ------------------------------------------------------------
>
> Key: FLINK-8790
> URL: https://issues.apache.org/jira/browse/FLINK-8790
> Project: Flink
> Issue Type: Improvement
> Components: State Backends, Checkpointing
> Affects Versions: 1.5.0
> Reporter: Sihua Zhou
> Assignee: Sihua Zhou
> Priority: Major
> Fix For: 1.6.0
>
>
> When there are multi state handle to be restored, we can improve the
> performance as follow:
> 1. Choose the best state handle to init the target db
> 2. Use the other state handles to create temp db, and clip the db according
> to the target key group range (via rocksdb.deleteRange()), this can help use
> get rid of the `key group check` in
> `data insertion loop` and also help us get rid of traversing the useless
> record.
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