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https://issues.apache.org/jira/browse/FLINK-9377?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16643413#comment-16643413
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ASF GitHub Bot commented on FLINK-9377:
---------------------------------------
dawidwys commented on a change in pull request #6711: [FLINK-9377] [core, state
backends] Remove serializers from checkpoints
URL: https://github.com/apache/flink/pull/6711#discussion_r223689536
##########
File path:
flink-runtime/src/main/java/org/apache/flink/runtime/state/KeyedBackendSerializationProxy.java
##########
@@ -44,7 +47,17 @@
*/
public class KeyedBackendSerializationProxy<K> extends
VersionedIOReadableWritable {
- public static final int VERSION = 5;
+ public static final int VERSION = 6;
+
+ private static final Map<Integer, Integer>
META_INFO_SNAPSHOT_FORMAT_VERSION_MAPPER = new HashMap<>();
+ static {
Review comment:
Agree we should keep track of the mapping. I just felt we could improve the
clarity of the tracking even a bit more, but I could not think of a better
solution right now. But as I said I think we could try make it a bit more
straightforward in some follow-up.
Just to sum it up. I think it is absolutely ok for this PR, but I have a
feeling we could improve readability of this mapping **even more** in the
future.
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> Remove writing serializers as part of the checkpoint meta information
> ---------------------------------------------------------------------
>
> Key: FLINK-9377
> URL: https://issues.apache.org/jira/browse/FLINK-9377
> Project: Flink
> Issue Type: Sub-task
> Components: State Backends, Checkpointing
> Reporter: Tzu-Li (Gordon) Tai
> Assignee: Tzu-Li (Gordon) Tai
> Priority: Critical
> Labels: pull-request-available
> Fix For: 1.7.0
>
>
> When writing meta information of a state in savepoints, we currently write
> both the state serializer as well as the state serializer's configuration
> snapshot.
> Writing both is actually redundant, as most of the time they have identical
> information.
> Moreover, the fact that we use Java serialization to write the serializer
> and rely on it to be re-readable on the restore run, already poses problems
> for serializers such as the {{AvroSerializer}} (see discussion in FLINK-9202)
> to perform even a compatible upgrade.
> The proposal here is to leave only the config snapshot as meta information,
> and use that as the single source of truth of information about the schema of
> serialized state.
> The config snapshot should be treated as a factory (or provided to a
> factory) to re-create serializers capable of reading old, serialized state.
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