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https://issues.apache.org/jira/browse/FLINK-4108?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15577612#comment-15577612
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ASF GitHub Bot commented on FLINK-4108:
---------------------------------------
Github user asfgit closed the pull request at:
https://github.com/apache/flink/pull/2619
> NPE in Row.productArity
> -----------------------
>
> Key: FLINK-4108
> URL: https://issues.apache.org/jira/browse/FLINK-4108
> Project: Flink
> Issue Type: Bug
> Components: Batch Connectors and Input/Output Formats, Type
> Serialization System
> Affects Versions: 1.1.0
> Reporter: Martin Scholl
> Assignee: Timo Walther
>
> [this is my first issue request here, please apologize if something is
> missing]
> JDBCInputFormat of flink 1.1-SNAPSHOT fails with an NPE in Row.productArity:
> {quote}
> java.io.IOException: Couldn't access resultSet
> at
> org.apache.flink.api.java.io.jdbc.JDBCInputFormat.nextRecord(JDBCInputFormat.java:288)
> at
> org.apache.flink.api.java.io.jdbc.JDBCInputFormat.nextRecord(JDBCInputFormat.java:98)
> at
> org.apache.flink.runtime.operators.DataSourceTask.invoke(DataSourceTask.java:162)
> at org.apache.flink.runtime.taskmanager.Task.run(Task.java:588)
> at java.lang.Thread.run(Thread.java:745)
> Caused by: java.lang.NullPointerException
> at org.apache.flink.api.table.Row.productArity(Row.scala:28)
> at
> org.apache.flink.api.java.io.jdbc.JDBCInputFormat.nextRecord(JDBCInputFormat.java:279)
> ... 4 more
> {quote}
> The code reproduce this can be found in this gist:
> https://gist.github.com/zeitgeist/b91a60460661618ca4585e082895c616
> The reason for the NPE, I believe, is the way through which Flink creates Row
> instances through Kryo. As Row expects the number of fields to allocate as a
> parameter, which Kryo does not provide, the ‘fields’ member of Row ends up
> being null. As I’m neither a reflection nor a Kryo expert, I rather leave a
> true analysis to more knowledgable programmers.
> Part of the aforementioned example is a not very elegant workaround though a
> custom type and a cast (function {{jdbcNoIssue}} + custom Row type {{MyRow}})
> to serve as a further hint towards my theory.
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