Hyukjin Kwon created SPARK-15474:
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Summary: 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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