[jira] [Commented] (FLINK-4108) NPE in Row.productArity

["Timo Walther (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/FLINK-4108?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15561763#comment-15561763 ] 

Timo Walther commented on FLINK-4108:
-------------------------------------

Actually, RowTypeInfo was intended for the Table API only. If it is used outside of the Table API there should be additional tests.

> 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
>
> [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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