Make sense, Thanks a lot, Mingliang. Another quick question: why there is a shell command that can copy a HDFS file to another HDFS file, but there is no API that can do this, the API only support copying file from local to HDFS, so that I should call multiple APIs to implement this, is that correct? Thanks.
On Fri, May 20, 2016 at 5:44 PM, Mingliang Liu <m...@hortonworks.com> wrote: > Kun, > > I think you need to be ware of the difference between client and server > side logic. Perhaps you’re more interested in the client side in this case. > The commands are generally running in the shell, and > org.apache.hadoop.fs.shell package is a good place to start. Specially, > have a look at CommandWithDestination.java. > > Ciao, > > L > > On May 20, 2016, at 12:05 PM, Kun Ren <ren.h...@gmail.com> wrote: > > Hi Genius, > > Currently I debugged the cp and mv operations, for example: > (1) ./bin/hdfs dfs -cp input/a.xml input/b.xml > (2)./bin/hdfs dfs -mv input/a.xml input/b.xml > > My understanding is that for operation cp, it will create a new file b.xml, > and will copy the content of a.xml to b.xml; For mv operations, it will > create b.xml and copy the content of a.xml to b.xml, and delete the a.xml. > > However, when I debug the code, i found that both operations will finally > go through the create() method in NameNodeRpcServer.java, but I didn't see > any calls to copy and delete function, could you please point out to me > where I can debug and see the full logic of the cp and mv operations. > Thanks a lot. > > >
