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1.问题描述

在CDH集群中我们需要将Hive表的数据导入到RDBMS数据库中，使用Sqoop工具可以方便的将Hive表数据抽取到RDBMS数据库中，在使用Sqoop抽取Hive Parquet表时作业执行异常。

Sqoop抽数脚本：

sqoop export

--connect jdbc:mysql://localhost:3306/test_db

--username root

--password 123456

--table mytest_parquet

--export-dir /user/hive/warehouse/mytest_parquet

-m 1

异常日志：

17/12/17 01:18:52 ERROR sqoop.Sqoop: Got exception running Sqoop: org.kitesdk.data.DatasetNotFoundException: Descriptor location does not exist: hdfs://nameservice1/user/hive/warehouse/mytest_parquet/.metadata
org.kitesdk.data.DatasetNotFoundException: Descriptor location does not exist: hdfs://nameservice1/user/hive/warehouse/mytest_parquet/.metadata
        at org.kitesdk.data.spi.filesystem.FileSystemMetadataProvider.checkExists(FileSystemMetadataProvider.java:562)
        at org.kitesdk.data.spi.filesystem.FileSystemMetadataProvider.find(FileSystemMetadataProvider.java:605)
        at org.kitesdk.data.spi.filesystem.FileSystemMetadataProvider.load(FileSystemMetadataProvider.java:114)
        at org.kitesdk.data.spi.filesystem.FileSystemDatasetRepository.load(FileSystemDatasetRepository.java:197)
        at org.kitesdk.data.Datasets.load(Datasets.java:108)
        at org.kitesdk.data.Datasets.load(Datasets.java:140)
        at org.kitesdk.data.mapreduce.DatasetKeyInputFormat$ConfigBuilder.readFrom(DatasetKeyInputFormat.java:92)
        at org.kitesdk.data.mapreduce.DatasetKeyInputFormat$ConfigBuilder.readFrom(DatasetKeyInputFormat.java:139)
        at org.apache.sqoop.mapreduce.JdbcExportJob.configureInputFormat(JdbcExportJob.java:84)
        at org.apache.sqoop.mapreduce.ExportJobBase.runExport(ExportJobBase.java:429)
        at org.apache.sqoop.manager.SqlManager.exportTable(SqlManager.java:931)
        at org.apache.sqoop.tool.ExportTool.exportTable(ExportTool.java:80)
        at org.apache.sqoop.tool.ExportTool.run(ExportTool.java:99)
        at org.apache.sqoop.Sqoop.run(Sqoop.java:147)
        at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
        at org.apache.sqoop.Sqoop.runSqoop(Sqoop.java:183)
        at org.apache.sqoop.Sqoop.runTool(Sqoop.java:234)
        at org.apache.sqoop.Sqoop.runTool(Sqoop.java:243)
        at org.apache.sqoop.Sqoop.main(Sqoop.java:252)
[ec2-user@ip-172-31-22-86 ~]$

2.解决方法

1.将Sqoop抽数脚本修改为如下：

sqoop export 
--connect jdbc:mysql://ip-172-31-22-86.ap-southeast-1.compute.internal:3306/test_db 
--username testuser 
--password password 
--table mytest_parquet 
--hcatalog-database default 
--hcatalog-table mytest_parquet --num-mappers 1

参数说明：

--table：MySQL库中的表名

--hcatalog-database：Hive中的库名

--hcatalog-table：Hive库中的表名，需要抽数的表

--num-mappers：执行作业的Map数

2.修改后执行抽数作业