我正试图使用sqoop将一个表作为avrodatafile从teradata导入hdfs，但遇到了一些问题。
作为文本文件导入时一切正常。但是，当我将--as avrodatafile添加到sqoop命令的末尾时，会得到一个npe，即：

ERROR sqoop.Sqoop: Got exception running Sqoop     java.lang.NullPointerException
java.lang.NullPointerException
at org.apache.sqoop.manager.SqlManager.execute(SqlManager.java:763)
at org.apache.sqoop.manager.SqlManager.execute(SqlManager.java:786)
at org.apache.sqoop.manager.SqlManager.getColumnInfoForRawQuery(SqlManager.java:289)
at org.apache.sqoop.manager.SqlManager.getColumnInfo(SqlManager.java:275)
    at org.apache.sqoop.manager.ConnManager.getColumnInfo(ConnManager.java:393)
    at org.apache.sqoop.orm.ClassWriter.getColumnInfo(ClassWriter.java:1854)
    at org.apache.sqoop.orm.AvroSchemaGenerator.generate(AvroSchemaGenerator.java:71)
    at org.apache.sqoop.orm.AvroSchemaGenerator.generate(AvroSchemaGenerator.java:65)
    at com.cloudera.connector.teradata.imports.BaseImportJob.configureInputFormat(BaseImportJob.java:165)
    at com.cloudera.connector.teradata.imports.TableImportJob.configureInputFormat(TableImportJob.java:32)
    at org.apache.sqoop.mapreduce.ImportJobBase.runImport(ImportJobBase.java:258)
    at com.cloudera.connector.teradata.TeradataManager.importTable(TeradataManager.java:273)
at org.apache.sqoop.tool.ImportTool.importTable(ImportTool.java:507)
at org.apache.sqoop.tool.ImportTool.run(ImportTool.java:615)
at org.apache.sqoop.Sqoop.run(Sqoop.java:143)
at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:179)
at org.apache.sqoop.Sqoop.runTool(Sqoop.java:218)
at org.apache.sqoop.Sqoop.runTool(Sqoop.java:227)
at org.apache.sqoop.Sqoop.main(Sqoop.java:236)"

不确定出了什么问题