Thanks Harsh. However, if I compress the MapFile using the MapFile.Writer Constructor option and then put it in a DistributedCache, how do I uncompress it in the Map/Reduce? There isn't any API method to do that apparently. Regards,Abhijit
> From: ha...@cloudera.com > Date: Sun, 11 Aug 2013 12:56:43 +0530 > Subject: Re: How to compress MapFile programmatically > To: user@hadoop.apache.org > > A MapFile isn't a directory. It is a directory _containing_ two files. > You cannot "open" a directory for reading. > > The MapFile API is documented at > http://hadoop.apache.org/docs/stable/api/org/apache/hadoop/io/MapFile.html > and thats what you're to be using for reading/writing them. > > Compression is a simple option you need to provide when invoking the > writer: > http://hadoop.apache.org/docs/stable/api/org/apache/hadoop/io/MapFile.Writer.html#MapFile.Writer(org.apache.hadoop.conf.Configuration,%20org.apache.hadoop.fs.FileSystem,%20java.lang.String,%20org.apache.hadoop.io.WritableComparator,%20java.lang.Class,%20org.apache.hadoop.io.SequenceFile.CompressionType,%20org.apache.hadoop.io.compress.CompressionCodec,%20org.apache.hadoop.util.Progressable) > > On Sun, Aug 11, 2013 at 1:46 AM, Abhijit Sarkar > <abhijit.sar...@gmail.com> wrote: > > Hi, > > I'm a Hadoop newbie. This is my first question to this mailing list, hoping > > for a good start :) > > > > MapFile is a directory so when I try to open an InputStream to it, it fails > > with FileNotFoundException. How do I compress MapFile programmatically? > > > > Code snippet: > > final FileSystem fs = FileSystem.get(conf); > > final InputStream inputStream = fs.open(new Path(uncompressedStr)); > > > > Exception: > > java.io.FileNotFoundException: /some/directory (No such file or directory) > > at java.io.FileInputStream.open(Native Method) > > at java.io.FileInputStream.<init>(FileInputStream.java:120) > > at > > org.apache.hadoop.fs.RawLocalFileSystem$TrackingFileInputStream.<init>(RawLocalFileSystem.java:71) > > at > > org.apache.hadoop.fs.RawLocalFileSystem$LocalFSFileInputStream.<init>(RawLocalFileSystem.java:107) > > at org.apache.hadoop.fs.RawLocalFileSystem.open(RawLocalFileSystem.java:177) > > at > > org.apache.hadoop.fs.ChecksumFileSystem$ChecksumFSInputChecker.<init>(ChecksumFileSystem.java:126) > > at org.apache.hadoop.fs.ChecksumFileSystem.open(ChecksumFileSystem.java:283) > > at org.apache.hadoop.fs.FileSystem.open(FileSystem.java:427) > > at name.abhijitsarkar.learning.hadoop.io.IOUtils.compress(IOUtils.java:104) > > > > Regards, > > Abhijit > > > > -- > Harsh J
