我使用Apache Spark 2.1.1（使用2.1.0，它是相同的，今天切换）。 我有一个数据集：
root
|-- muons: array (nullable = true)
| |-- element: struct (containsNull = true)
| | |-- reco::Candidate: struct (nullable = true)
| | |-- qx3_: integer (nullable = true)
| | |-- pt_: float (nullable = true)
| | |-- eta_: float (nullable = true)
| | |-- phi_: float (nullable = true)
| | |-- mass_: float (nullable = true)
| | |-- vertex_: struct (nullable = true)
| | | |-- fCoordinates: struct (nullable = true)
| | | | |-- fX: float (nullable = true)
| | | | |-- fY: float (nullable = true)
| | | | |-- fZ: float (nullable = true)
| | |-- pdgId_: integer (nullable = true)
| | |-- status_: integer (nullable = true)
| | |-- cachePolarFixed_: struct (nullable = true)
| | |-- cacheCartesianFixed_: struct (nullable = true)
如您所见，此架构中有3个空结构。我100％知道我可以阅读/操纵/做任何事情。但是，当我尝试在镶木地板中写入磁盘时，我得到以下异常：
dsReduced.write.format("parquet").save(outputPathName):
java.lang.IllegalStateException: Cannot build an empty group
at org.apache.parquet.Preconditions.checkState(Preconditions.java:91)
at org.apache.parquet.schema.Types$BaseGroupBuilder.build(Types.java:622)
at org.apache.parquet.schema.Types$BaseGroupBuilder.build(Types.java:497)
at org.apache.parquet.schema.Types$Builder.named(Types.java:286)
at org.apache.spark.sql.execution.datasources.parquet.ParquetSchemaConverter.convertField(ParquetSchemaConverter.scala:535)
at org.apache.spark.sql.execution.datasources.parquet.ParquetSchemaConverter.convertField(ParquetSchemaConverter.scala:321)
at org.apache.spark.sql.execution.datasources.parquet.ParquetSchemaConverter$$anonfun$convertField$1.apply(ParquetSchemaConverter.scala:534)
at org.apache.spark.sql.execution.datasources.parquet.ParquetSchemaConverter$$anonfun$convertField$1.apply(ParquetSchemaConverter.scala:533)
所以，基本上我想了解它是否是一个错误或预期的行为？我还假设它与空结构有关。任何帮助都会非常感激！
更新：我已经快速创建了剥离版本，并且该版本没有任何问题！任何见解都会非常有用！
VK
答案 0 :(得分：6)