This directory contains the hdfs extensions needed to make rocksdb store
files in HDFS.

The hdfs.h file is copied from the Apache Hadoop 1.0 source code. 
It defines the libhdfs library
(http://hadoop.apache.org/common/docs/r0.20.2/libhdfs.html) to access 
data in HDFS.  The libhdfs.a is copied from the Apache Hadoop 1.0 build. 
It implements the API defined in hdfs.h. If your hadoop cluster is running
a different hadoop release, then install these two files manually from your
hadoop distribution and then recompile rocksdb.

The env_hdfs.h file defines the rocksdb objects that are needed to talk to an
underlying filesystem. 

If you want to compile rocksdb with hdfs support, please set the following
enviroment variables appropriately:
   USE_HDFS=1
   JAVA_HOME=/usr/local/jdk-6u22-64
   LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/usr/local/jdk-6u22-64/jre/lib/amd64/server:/usr/local/jdk-6u22-64/jre/lib/amd64/:./snappy/libs
   make clean all db_bench

To run dbbench,
  set CLASSPATH to include your hadoop distribution
  db_bench --hdfs="hdfs://hbaseudbperf001.snc1.facebook.com:9000"