The sequence file writer definitely does it serially as you can only ever write to the end of a file in Hadoop.
Doing copyFromLocal could write multiple files in parallel (I'm not sure if it does or not), but a single file would be written serially. -Joey On Tue, May 17, 2011 at 5:44 PM, Mapred Learn <[email protected]> wrote: > Hi, > My question is when I run a command from hdfs client, for eg. hadoop fs > -copyFromLocal or create a sequence file writer in java code and append > key/values to it through Hadoop APIs, does it internally transfer/write data > to HDFS serially or in parallel ? > > Thanks in advance, > -JJ > -- Joseph Echeverria Cloudera, Inc. 443.305.9434
