Apache Hive : WebHCat Reference MapReduceStream

MapReduce Streaming Job — POST mapreduce/streaming

Description

Create and queue a Hadoop streaming MapReduce job.

Version: Hive 0.13.0 and later

As of Hive 0.13.0, GET version/hadoop displays the Hadoop version used for the MapReduce job.

URL

http://www.myserver.com/templeton/v1/mapreduce/streaming

Parameters

Name Description Required? Default
input Location of the input data in Hadoop. Required None
output Location in which to store the output data. If not specified, WebHCat will store the output in a location that can be discovered using the queue resource. Optional See description
mapper Location of the mapper program in Hadoop. Required None
reducer Location of the reducer program in Hadoop. Required None
file Add an HDFS file to the distributed cache. Optional None
define Set a Hadoop configuration variable using the syntax define=NAME=VALUE Optional None
cmdenv Set an environment variable using the syntax cmdenv=NAME=VALUE Optional None
arg Set a program argument. Optional None
statusdir A directory where WebHCat will write the status of the Map Reduce job. If provided, it is the caller’s responsibility to remove this directory when done. Optional None
enablelog If statusdir is set and enablelog is “true”, collect Hadoop job configuration and logs into a directory named $statusdir/logs after the job finishes. Both completed and failed attempts are logged. The layout of subdirectories in $statusdir/logs is: logs/$job_id (directory for $job_id) logs/$job_id/job.xml.html logs/$job_id/$attempt_id (directory for $attempt_id) logs/$job_id/$attempt_id/stderr logs/$job_id/$attempt_id/stdout logs/$job_id/$attempt_id/syslog This parameter was introduced in Hive 0.12.0. (See HIVE-4531.) Optional in Hive 0.12.0+ None
callback Define a URL to be called upon job completion. You may embed a specific job ID into this URL using $jobId. This tag will be replaced in the callback URL with this job’s job ID. Optional None

The standard parameters are also supported.

Results

Name Description
id A string containing the job ID similar to “job_201110132141_0001”.
info A JSON object containing the information returned when the job was queued. See the Hadoop documentation (Class TaskController) for more information.

Example

Code and Data Setup

% cat mydata/file01 mydata/file02
Hello World Bye World
Hello Hadoop Goodbye Hadoop

% hadoop fs -put mydata/ .

% hadoop fs -ls mydata
Found 2 items
-rw-r--r--   1 ctdean supergroup         23 2011-11-11 13:29 /user/ctdean/mydata/file01
-rw-r--r--   1 ctdean supergroup         28 2011-11-11 13:29 /user/ctdean/mydata/file02

Curl Command

% curl -s -d input=mydata \
       -d output=mycounts \
       -d mapper=/bin/cat \
       -d reducer="/usr/bin/wc -w" \
       'http://localhost:50111/templeton/v1/mapreduce/streaming?user.name=ekoifman'

Version information

Prior to Hive 0.13.0, user.name was specified in POST requests as a form parameter: curl -d user.name=*<user>*.

In Hive 0.13.0 onward, user.name should be specified in the query string (as shown above): 'http://.../templeton/v1/mapreduce/streaming?user.name=*<name>*'. Specifying user.name as a form parameter is deprecated.

JSON Output

{
 "id": "job_201111111311_0008",
 "info": {
          "stdout": "packageJobJar: [] [/Users/ctdean/var/hadoop/hadoop-0.20.205.0/share/hadoop/contrib/streaming/hadoop-streaming-0.20.205.0.jar...
                    templeton-job-id:job_201111111311_0008
                    ",
          "stderr": "11/11/11 13:26:43 WARN mapred.JobClient: Use GenericOptionsParser for parsing the arguments
                    11/11/11 13:26:43 INFO mapred.FileInputFormat: Total input paths to process : 2
                    ",
          "exitcode": 0
         }
}

Example Results

% hadoop fs -ls mycounts
Found 3 items
-rw-r--r--   1 ctdean supergroup          0 2011-11-11 13:27 /user/ctdean/mycounts/_SUCCESS
drwxr-xr-x   - ctdean supergroup          0 2011-11-11 13:26 /user/ctdean/mycounts/_logs
-rw-r--r--   1 ctdean supergroup         10 2011-11-11 13:27 /user/ctdean/mycounts/part-00000

% hadoop fs -cat mycounts/part-00000
      8

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