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https://issues.apache.org/jira/browse/FLINK-33355?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17779352#comment-17779352
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zhang commented on FLINK-33355:
-------------------------------
[~yunta]
{code:java}
StreamExecutionEnvironment env =
StreamExecutionEnvironment.getExecutionEnvironment();
SqlServerSourceBuilder.SqlServerIncrementalSource<String> cdcSource = ...;
DataStreamSource<String> cdcStream = env.fromSource(cdcSource,
WatermarkStrategy.noWatermarks(), "cdc");
cdcStream.windowAll(TumblingProcessingTimeWindows.of(Time.seconds(10)))
.trigger(new CustomTrigger<>())
.apply(new CustomFunction()).print();
env.execute(); {code}
For the task mentioned above, if I reduce the parallelism from n to 1, will
encounter the previously mentioned error.
{code:java}
StreamExecutionEnvironment env =
StreamExecutionEnvironment.getExecutionEnvironment();
SqlServerSourceBuilder.SqlServerIncrementalSource<String> cdcSource = ...;
DataStreamSource<String> cdcStream = env.fromSource(cdcSource,
WatermarkStrategy.noWatermarks(), "cdc"); cdcStream.print();
env.execute(); {code}
But doing this doesn't result in an error, so I suspect it might be caused by
window operators.
> can't reduce the parallelism from 'n' to '1' when recovering through a
> savepoint.
> ---------------------------------------------------------------------------------
>
> Key: FLINK-33355
> URL: https://issues.apache.org/jira/browse/FLINK-33355
> Project: Flink
> Issue Type: Bug
> Components: API / Core
> Environment: flink 1.17.1
> Reporter: zhang
> Priority: Major
>
> If the program includes operators with window, it is not possible to reduce
> the parallelism of the operators from n to 1 when restarting from a
> savepoint, and it will result in an error:
> {code:java}
> //IllegalStateException: Failed to rollback to checkpoint/savepoint
> Checkpoint Metadata. Max parallelism mismatch between checkpoint/savepoint
> state and new program. Cannot map operator 0e059b9f403cf6f35592ab773c9408d4
> with max parallelism 128 to new program with max parallelism 1. This
> indicates that the program has been changed in a non-compatible way after the
> checkpoint/savepoint. {code}
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