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https://issues.apache.org/jira/browse/SPARK-15474?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15890639#comment-15890639
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Nicholas Chammas commented on SPARK-15474:
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There is a related discussion on ORC-152 which suggests that this is an issue
with Spark's DataFrame writer for ORC. If there is evidence that this is not
the case, it would be good to post it directly on ORC-152 so we can get input
from people on that project.
> ORC data source fails to write and read back empty dataframe
> -------------------------------------------------------------
>
> Key: SPARK-15474
> URL: https://issues.apache.org/jira/browse/SPARK-15474
> Project: Spark
> Issue Type: Bug
> Components: SQL
> Affects Versions: 2.0.0
> Reporter: Hyukjin Kwon
>
> Currently ORC data source fails to write and read empty data.
> The code below:
> {code}
> val emptyDf = spark.range(10).limit(0)
> emptyDf.write
> .format("orc")
> .save(path.getCanonicalPath)
> val copyEmptyDf = spark.read
> .format("orc")
> .load(path.getCanonicalPath)
> copyEmptyDf.show()
> {code}
> throws an exception below:
> {code}
> Unable to infer schema for ORC at
> /private/var/folders/9j/gf_c342d7d150mwrxvkqnc180000gn/T/spark-5b7aa45b-a37d-43e9-975e-a15b36b370da.
> It must be specified manually;
> org.apache.spark.sql.AnalysisException: Unable to infer schema for ORC at
> /private/var/folders/9j/gf_c342d7d150mwrxvkqnc180000gn/T/spark-5b7aa45b-a37d-43e9-975e-a15b36b370da.
> It must be specified manually;
> at
> org.apache.spark.sql.execution.datasources.DataSource$$anonfun$16.apply(DataSource.scala:352)
> at
> org.apache.spark.sql.execution.datasources.DataSource$$anonfun$16.apply(DataSource.scala:352)
> at scala.Option.getOrElse(Option.scala:121)
> at
> org.apache.spark.sql.execution.datasources.DataSource.resolveRelation(DataSource.scala:351)
> at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:130)
> at org.apache.spark.sql.DataFrameReader.load(DataFrameReader.scala:140)
> at
> org.apache.spark.sql.sources.HadoopFsRelationTest$$anonfun$32$$anonfun$apply$mcV$sp$47.apply(HadoopFsRelationTest.scala:892)
> at
> org.apache.spark.sql.sources.HadoopFsRelationTest$$anonfun$32$$anonfun$apply$mcV$sp$47.apply(HadoopFsRelationTest.scala:884)
> at
> org.apache.spark.sql.test.SQLTestUtils$class.withTempPath(SQLTestUtils.scala:114)
> {code}
> Note that this is a different case with the data below
> {code}
> val emptyDf = spark.createDataFrame(spark.sparkContext.emptyRDD[Row], schema)
> {code}
> In this case, any writer is not initialised and created. (no calls of
> {{WriterContainer.writeRows()}}.
> For Parquet and JSON, it works but ORC does not.
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