Re: Spark SQL "lateral view explode" doesn't work, and unable to save array types to Parquet

[Cheng Lian]

Thanks for the detailed information!

On 3/27/15 9:16 PM, Jon Chase wrote:

Done. I also updated the name on the ticket to include both issues. "Spark SQL arrays: "explode()" fails and cannot save array type to Parquet"

https://issues.apache.org/jira/browse/SPARK-6570

On Fri, Mar 27, 2015 at 8:14 AM, Cheng Lian <lian.cs....@gmail.com <mailto:lian.cs....@gmail.com>> wrote:

    Forgot to mention that, would you mind to also provide the full
    stack trace of the exception thrown in the saveAsParquetFile call?
    Thanks!

    Cheng

    On 3/27/15 7:35 PM, Jon Chase wrote:

    https://issues.apache.org/jira/browse/SPARK-6570

    I also left in the call to saveAsParquetFile(), as it produced a
    similar exception (though there was no use of explode there).

    On Fri, Mar 27, 2015 at 7:20 AM, Cheng Lian
    <lian.cs....@gmail.com <mailto:lian.cs....@gmail.com>> wrote:

        This should be a bug in the Explode.eval(), which always
        assumes the underlying SQL array is represented by a Scala
        Seq. Would you mind to open a JIRA ticket for this? Thanks!

        Cheng

        On 3/27/15 7:00 PM, Jon Chase wrote:

        Spark 1.3.0

        Two issues:

        a) I'm unable to get a "lateral view explode" query to work
        on an array type
        b) I'm unable to save an array type to a Parquet file

        I keep running into this:

        java.lang.ClassCastException: [I cannot be cast to
        scala.collection.Seq

        Here's a stack trace from the explode issue:

        root
         |-- col1: string (nullable = false)
         |-- col2s: array (nullable = true)
         |    |-- element: integer (containsNull = true)

        ERROR org.apache.spark.executor.Executor Exception in task
        7.0 in stage 1.0 (TID 15)
        java.lang.ClassCastException: [I cannot be cast to
        scala.collection.Seq
        at
        
org.apache.spark.sql.catalyst.expressions.Explode.eval(generators.scala:125)
        ~[spark-catalyst_2.10-1.3.0.jar:1.3.0]
        at
        
org.apache.spark.sql.execution.Generate$$anonfun$2$$anonfun$apply$1.apply(Generate.scala:70)
        ~[spark-sql_2.10-1.3.0.jar:1.3.0]
        at
        
org.apache.spark.sql.execution.Generate$$anonfun$2$$anonfun$apply$1.apply(Generate.scala:69)
        ~[spark-sql_2.10-1.3.0.jar:1.3.0]
        at
        scala.collection.Iterator$$anon$13.hasNext(Iterator.scala:371)
        ~[scala-library-2.10.4.jar:na]
        at
        scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:327)
        ~[scala-library-2.10.4.jar:na]
        at
        scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:327)
        ~[scala-library-2.10.4.jar:na]
        at
        scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:327)
        ~[scala-library-2.10.4.jar:na]
        at
        scala.collection.Iterator$class.foreach(Iterator.scala:727)
        ~[scala-library-2.10.4.jar:na]
        at
        scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
        ~[scala-library-2.10.4.jar:na]
        at
        scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:48)
        ~[scala-library-2.10.4.jar:na]
        at
        
scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:103)
        ~[scala-library-2.10.4.jar:na]
        at
        scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:47)
        ~[scala-library-2.10.4.jar:na]
        at scala.collection.TraversableOnce$class.to
        <http://class.to>(TraversableOnce.scala:273)
        ~[scala-library-2.10.4.jar:na]
        at scala.collection.AbstractIterator.to
        <http://scala.collection.AbstractIterator.to>(Iterator.scala:1157)
        ~[scala-library-2.10.4.jar:na]
        at
        
scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:265)
        ~[scala-library-2.10.4.jar:na]
        at
        scala.collection.AbstractIterator.toBuffer(Iterator.scala:1157)
        ~[scala-library-2.10.4.jar:na]
        at
        
scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:252)
        ~[scala-library-2.10.4.jar:na]
        at
        scala.collection.AbstractIterator.toArray(Iterator.scala:1157)
        ~[scala-library-2.10.4.jar:na]
        at org.apache.spark.rdd.RDD$$anonfun$17.apply(RDD.scala:813)
        ~[spark-core_2.10-1.3.0.jar:1.3.0]
        at org.apache.spark.rdd.RDD$$anonfun$17.apply(RDD.scala:813)
        ~[spark-core_2.10-1.3.0.jar:1.3.0]
        at
        
org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1497)
        ~[spark-core_2.10-1.3.0.jar:1.3.0]
        at
        
org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1497)
        ~[spark-core_2.10-1.3.0.jar:1.3.0]
        at
        org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:61)
        ~[spark-core_2.10-1.3.0.jar:1.3.0]
        at org.apache.spark.scheduler.Task.run(Task.scala:64)
        ~[spark-core_2.10-1.3.0.jar:1.3.0]
        at
        org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:203)
        ~[spark-core_2.10-1.3.0.jar:1.3.0]
        at
        
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        [na:1.8.0_31]
        at
        
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        [na:1.8.0_31]
        at java.lang.Thread.run(Thread.java:745) [na:1.8.0_31]
        WARN  o.a.spark.scheduler.TaskSetManager Lost task 7.0 in
        stage 1.0 (TID 15, localhost): java.lang.ClassCastException:
        [I cannot be cast to scala.collection.Seq
        at
        
org.apache.spark.sql.catalyst.expressions.Explode.eval(generators.scala:125)
        at
        
org.apache.spark.sql.execution.Generate$$anonfun$2$$anonfun$apply$1.apply(Generate.scala:70)
        at
        
org.apache.spark.sql.execution.Generate$$anonfun$2$$anonfun$apply$1.apply(Generate.scala:69)
        at
        scala.collection.Iterator$$anon$13.hasNext(Iterator.scala:371)
        at
        scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:327)
        at
        scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:327)
        at
        scala.collection.Iterator$$anon$11.hasNext(Iterator.scala:327)
        at scala.collection.Iterator$class.foreach(Iterator.scala:727)
        at
        scala.collection.AbstractIterator.foreach(Iterator.scala:1157)
        at
        scala.collection.generic.Growable$class.$plus$plus$eq(Growable.scala:48)
        at
        
scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:103)
        at
        scala.collection.mutable.ArrayBuffer.$plus$plus$eq(ArrayBuffer.scala:47)
        at scala.collection.TraversableOnce$class.to
        <http://class.to>(TraversableOnce.scala:273)
        at scala.collection.AbstractIterator.to
        <http://scala.collection.AbstractIterator.to>(Iterator.scala:1157)
        at
        
scala.collection.TraversableOnce$class.toBuffer(TraversableOnce.scala:265)
        at
        scala.collection.AbstractIterator.toBuffer(Iterator.scala:1157)
        at
        
scala.collection.TraversableOnce$class.toArray(TraversableOnce.scala:252)
        at
        scala.collection.AbstractIterator.toArray(Iterator.scala:1157)
        at org.apache.spark.rdd.RDD$$anonfun$17.apply(RDD.scala:813)
        at org.apache.spark.rdd.RDD$$anonfun$17.apply(RDD.scala:813)
        at
        
org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1497)
        at
        
org.apache.spark.SparkContext$$anonfun$runJob$5.apply(SparkContext.scala:1497)
        at
        org.apache.spark.scheduler.ResultTask.runTask(ResultTask.scala:61)
        at org.apache.spark.scheduler.Task.run(Task.scala:64)
        at
        org.apache.spark.executor.Executor$TaskRunner.run(Executor.scala:203)
        at
        
java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at
        
java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745)



        Maybe I'm defining the schema incorrectly?



        This test demonstrates both issues:

            @Rule
            public TemporaryFolder tmp = new TemporaryFolder();

            @Test
            public void testPercentileWithExplode() throws Exception {
                StructType schema =
        DataTypes.createStructType(Lists.newArrayList(
        DataTypes.createStructField("col1", DataTypes.StringType,
        false),
        DataTypes.createStructField("col2s",
        DataTypes.createArrayType(DataTypes.IntegerType, true), true)
                ));

                JavaRDD<Row> rowRDD = sc.parallelize(Lists.newArrayList(
        RowFactory.create("test", new int[]{1, 2, 3})
                ));

                DataFrame df = sql.createDataFrame(rowRDD, schema);
        df.registerTempTable("df");
                df.printSchema();

                List<int[]> ints = sql.sql("select col2s from
        df").javaRDD()
        .map(row -> (int[]) row.get(0)).collect();
                assertEquals(1, ints.size());
                assertArrayEquals(new int[]{1, 2, 3}, ints.get(0));


                // fails: lateral view explode does not work:
        java.lang.ClassCastException: [I cannot be cast to
        scala.collection.Seq
                List<Integer> explodedInts = sql.sql("select col2
        from df lateral view explode(col2s) splode as col2").javaRDD()
                  .map(row -> row.getInt(0)).collect();
                assertEquals(3, explodedInts.size());
        assertEquals(Lists.newArrayList(1, 2, 3), explodedInts);


                // fails: java.lang.ClassCastException: [I cannot be
        cast to scala.collection.Seq
        df.saveAsParquetFile(tmp.getRoot().getAbsolutePath() +
        "/parquet");


                DataFrame loadedDf =
        sql.load(tmp.getRoot().getAbsolutePath() + "/parquet");
        loadedDf.registerTempTable("loadedDf");
                List<int[]> moreInts = sql.sql("select col2s from
        loadedDf").javaRDD()
            .map(row -> (int[]) row.get(0)).collect();
                assertEquals(1, moreInts.size());
                assertArrayEquals(new int[]{1, 2, 3}, moreInts.get(0));
            }