Hello everyone,

JDBCInputFormat of flink 1.1-SNAPSHOT fails with an NPE in Row.productArity:

%% snip %%
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
%% snip %%

Find the example code triggering this attached to this email.

The reason, 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 not a reflection, etc. expert, I rather leave a true analysis to more 
knowledgable programmers.

Part of the attached example is a not very elegant workaround though a custom 
type and a cast (see jdbcNoIssue).

Am I doing something wrong as to the example code, or shall I open a JIRA 
ticket?


Thank you in advance,
Martin

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