hadoop - Sqoop append命令如何在hadoop中工作

Question

我对Sqoop --append命令有一个疑问，因为我们知道append命令将为现有表或记录添加一个值，但是在hadoop或hdfs中，update选项被禁止了如何工作？

Answer 1

从文档中

By default, imports go to a new target location. If the destination directory already exists in HDFS, Sqoop will refuse to import and overwrite that directory’s contents. If you use the --append argument, Sqoop will import data to a temporary directory and then rename the files into the normal target directory in a manner that does not conflict with existing filenames in that directory.