I know hadoop version 2.7‘s FileUtil has the copyMerge function that merges multiple files into a new one.
But the copyMerge function is no longer supported per the API in the 3.0 version.
Any ideas on how to merge all files within a directory into a new single file in the 3.0 version of hadoop?
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Answer
FileUtil#copyMerge method has been removed. See details for the major change:
https://issues.apache.org/jira/browse/HADOOP-12967
https://issues.apache.org/jira/browse/HADOOP-11392
You can use getmerge
Usage: hadoop fs -getmerge [-nl]
Takes a source directory and a destination file as input and concatenates files in src into the destination local file. Optionally -nl can be set to enable adding a newline character (LF) at the end of each file. -skip-empty-file can be used to avoid unwanted newline characters in case of empty files.
Examples:
hadoop fs -getmerge -nl /src /opt/output.txt hadoop fs -getmerge -nl /src/file1.txt /src/file2.txt /output.txt
Exit Code: Returns 0 on success and non-zero on error.