Changes between Initial Version and Version 1 of VNU120925/Lab7

Timestamp:

Oct 10, 2012, 11:43:24 PM (13 years ago)

Author:

jazz

Comment:

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VNU120925/Lab7

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+◢ <[wiki:VNU120925/Lab6 實作六]> | <[wiki:VNU120925 回課程大綱]> ▲ | <[wiki:VNU120925/Lab8 實作八]> ◣
+
+= 實作七 Lab 7 =
+
+[[PageOutline]]
+
+{{{
+#!html
+<div style="text-align: center;"><big style="font-weight: bold;"><big>在完全分散模式執行 MapReduce 基本運算<br/>Running MapReduce in Full Distributed Mode by Examples</big></big></div>
+}}}
+{{{
+#!text
+以下練習，請連線至 hadoop.nchc.org.tw 操作。底下的 hXXXX 等於您的用戶名稱。
+}}}
+
+== Sample 1 : WordCount ==
+ 
+ * 如名稱，WordCount會對所有的字作字數統計，並且從a-z作排列[[BR]]WordCount example will count each word shown in documents and sorting from a to z.
+{{{
+~$ hadoop fs -put /etc/hadoop/conf lab5_input
+~$ hadoop fs -rmr lab5_out2
+~$ hadoop jar hadoop-examples.jar wordcount lab5_input lab5_out2
+}}}
+ * 檢查輸出結果的方法同之前方法[[BR]]Let's check the computed result of '''wordcount''' from HDFS : 
+{{{
+$ hadoop fs -ls lab5_out2
+$ hadoop fs -cat lab5_out2/part-r-00000 
+}}}
+ * 結果如下[[BR]]You should see results like this: 
+{{{
+"".     4
+"*"     9
+"127.0.0.1"     3
+"AS     2
+"License");     2
+"_logs/history/"        1
+"alice,bob      9
+
+( ... skip ... )
+}}}
+
+== Sample 2: grep ==
+ 
+ * grep 這個命令是擷取文件裡面特定的字元，在Hadoop example中此指令可以擷取文件中有此指定文字的字串，並作計數統計[[BR]]grep is a command to extract specific characters in documents. In hadoop examples, you can use this command to extract strings match the regular expression and count for matched strings.
+{{{
+$ hadoop fs -ls lab5_input
+$ hadoop jar hadoop-examples.jar grep lab5_input lab5_out3 'dfs[a-z.]+' 
+}}}
+ * 運作的畫面如下：[[BR]]You should see procedure like this:  
+{{{
+11/04/19 10:00:20 INFO mapred.FileInputFormat: Total input paths to process : 25
+11/04/19 10:00:20 INFO mapred.JobClient: Running job: job_201104120101_0645
+11/04/19 10:00:21 INFO mapred.JobClient:  map 0% reduce 0%
+( ... skip ... )
+}}}
+ * 接著查看結果[[BR]]Let's check the computed result of '''grep''' from HDFS :
+{{{
+$ hadoop fs -ls lab5_out3
+Found 2 items
+drwx------   - hXXXX supergroup          0 2011-04-19 10:00 /user/hXXXX/lab5_out1/_logs
+-rw-r--r--   2 hXXXX supergroup       1146 2011-04-19 10:00 /user/hXXXX/lab5_out1/part-00000
+$ hadoop fs -cat lab5_out1/part-00000 
+}}}
+ * 結果如下[[BR]]You should see results like this: 
+{{{
+4       dfs.permissions
+4       dfs.replication
+4       dfs.name.dir
+3       dfs.namenode.decommission.interval.
+3       dfs.namenode.decommission.nodes.per.interval
+3       dfs.
+( ... skip ... )
+}}}
+
+== More Examples ==
+ 
+ 可執行的指令一覽表：[[BR]]Here is a list of hadoop examples :
+
+ || aggregatewordcount ||  An Aggregate based map/reduce program that counts the words in the input files. || 
+ || aggregatewordhist || An Aggregate based map/reduce program that computes the histogram of the words in the input files. || 
+ || grep ||  A map/reduce program that counts the matches of a regex in the input. || 
+ || join || A job that effects a join over sorted, equally partitioned datasets || 
+ || multifilewc ||  A job that counts words from several files. || 
+ || pentomino  || A map/reduce tile laying program to find solutions to pentomino problems. || 
+ || pi ||  A map/reduce program that estimates Pi using monte-carlo method. || 
+ || randomtextwriter ||  A map/reduce program that writes 10GB of random textual data per node. || 
+ || randomwriter || A map/reduce program that writes 10GB of random data per node. || 
+ || sleep ||  A job that sleeps at each map and reduce task. || 
+ || sort || A map/reduce program that sorts the data written by the random writer. || 
+ || sudoku ||  A sudoku solver. || 
+ || wordcount || A map/reduce program that counts the words in the input files. || 
+
+You could find more detail at [http://hadoop.apache.org/core/docs/current/api/org/apache/hadoop/examples/package-summary.html org.apache.hadoop.examples]