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From "Johann Kovacs (JIRA)" <j...@apache.org>
Subject [jira] [Created] (FLINK-2988) Cannot load DataSet[Row] from CSV file
Date Mon, 09 Nov 2015 15:06:11 GMT
Johann Kovacs created FLINK-2988:
------------------------------------

             Summary: Cannot load DataSet[Row] from CSV file
                 Key: FLINK-2988
                 URL: https://issues.apache.org/jira/browse/FLINK-2988
             Project: Flink
          Issue Type: Improvement
          Components: DataSet API, Table API
    Affects Versions: 0.10
            Reporter: Johann Kovacs
            Priority: Minor


Tuple classes (Java/Scala both) only have arity up to 25, meaning I cannot load a CSV file
with more than 25 columns directly as a DataSet\[TupleX\[...\]\].

An alternative to using Tuples is using the Table API's Row class, which allows for arbitrary-length,
arbitrary-type, runtime-supplied schemata (using RowTypeInfo) and index-based access.

However, trying to load a CSV file as a DataSet\[Row\] yields an exception:

{code}
val env = ExecutionEnvironment.createLocalEnvironment()
val filePath = "../someCsv.csv"
val typeInfo = new RowTypeInfo(Seq(BasicTypeInfo.STRING_TYPE_INFO, BasicTypeInfo.INT_TYPE_INFO),
Seq("word", "number"))
val source = env.readCsvFile(filePath)(ClassTag(classOf[Row]), typeInfo)
println(source.collect())
{code}
with someCsv.csv containing:
{code}
one,1
two,2
{code}
yields
{code}
Exception in thread "main" java.lang.ClassCastException: org.apache.flink.api.table.typeinfo.RowSerializer
cannot be cast to org.apache.flink.api.java.typeutils.runtime.TupleSerializerBase
	at org.apache.flink.api.scala.operators.ScalaCsvInputFormat.<init>(ScalaCsvInputFormat.java:46)
	at org.apache.flink.api.scala.ExecutionEnvironment.readCsvFile(ExecutionEnvironment.scala:282)
{code}

As a user I would like to be able to load a CSV file into a DataSet\[Row\], preferably having
a convenience method to specify the schema (RowTypeInfo), without having to use the "explicit
implicit parameters" syntax and specifying the ClassTag.



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