先看问题：

18/09/30 10:52:44 INFO mapreduce.ExportJobBase: Exported 0 records.
18/09/30 10:52:44 ERROR mapreduce.ExportJobBase: Export job failed!
18/09/30 10:52:44 DEBUG util.ClassLoaderStack: Restoring classloader: sun.misc.Launcher$AppClassLoader@6e1567f1
18/09/30 10:52:44 ERROR tool.ExportTool: Error during export:
Export job failed!
at org.apache.sqoop.mapreduce.ExportJobBase.runExport(ExportJobBase.java:445)
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)

sqoop导出任务不间断出问题 ，后来发现hive中的null值在文件按\N存储，所以导致导出字符异常，参考：
https://stackoverflow.com/questions/30736049/sqoop-export-is-failing-when-i-have-n-as-data

增加选项：
--input-null-string "\\\\N" --input-null-non-string "\\\\N"


-------
感觉在不断探坑。。。

从sqoop导出mysql，涉及hdfs、hive、cos（腾讯云对象存储）等数据源，sqoop 1.4.6导出 hive表到 mysql，如果需要用到update-key功能（根据主key更新或插入），1.4.6版本实现上有bug，1.4.7版本已经解决。

只能通过hdfs、cos方式导出，注意默认hive数据分隔符是 ctrl+a，所以需要制定分隔符"\0001"

问题：
18/09/29 16:25:42 WARN hcat.SqoopHCatUtilities: No files under /usr/local/service/hive/hcatalog/lib to add to distributed cache for hcatalog job
18/09/29 16:25:42 WARN hcat.SqoopHCatUtilities: No files under /usr/local/service/hive/hcatalog/share/hcatalog/storage-handlers to add to distributed cache for hcatalog job
18/09/29 16:25:42 ERROR sqoop.Sqoop: Got exception running Sqoop: java.lang.NullPointerException
java.lang.NullPointerException
at org.apache.sqoop.mapreduce.ExportJobBase.getFileType(ExportJobBase.java:127)
at org.apache.sqoop.mapreduce.ExportJobBase.isSequenceFiles(ExportJobBase.java:118)
at org.apache.sqoop.mapreduce.ExportJobBase.inputIsSequenceFiles(ExportJobBase.java:492)
at org.apache.sqoop.mapreduce.JdbcUpdateExportJob.getMapperClass(JdbcUpdateExportJob.java:69)
at org.apache.sqoop.mapreduce.ExportJobBase.configureMapper(ExportJobBase.java:268)
at org.apache.sqoop.mapreduce.ExportJobBase.runExport(ExportJobBase.java:426)
at org.apache.sqoop.manager.MySQLManager.upsertTable(MySQLManager.java:136)
at org.apache.sqoop.tool.ExportTool.exportTable(ExportTool.java:74)
at org.apache.sqoop.tool.ExportTool.run(ExportTool.java:100)
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)

解决方案：

sqoop export --connect jdbc:mysql://ip:port/db --table table_name
--username xxx --password xxx
--export-dir hdfs路径or cos路径
--update-key mysql-table-primary-key --update-mode allowinsert
--input-fields-terminated-by "\0001"