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19<body>
20<h2>org.apache.hadoop.mapred.lib.db Package</h2>
21<p>
22This package contains a library to read records from a database as an
23input to a mapreduce job, and write the output records to the database.   
24</p>
25<p>
26The Database to access can be configured using the static methods in the
27DBConfiguration class. Jobs reading input from a database should use
28DBInputFormat#setInput() to set the configuration. And jobs writing
29its output to the database should use DBOutputFormat#setOutput().
30</p>
31<p> 
32Tuples from/to the database are converted to/from Java objects using
33DBWritable methods. Typically, for each table in the db, a class extending
34DBWritable is defined, which holds the fields of the tuple. The fields
35of a record are read from the database using DBWritable#readFields(ResultSet),
36and written to the database using DBWritable#write(PreparedStatament
37statement).
38</p>
39<p>
40An example program using both DBInputFormat and DBOutputFormat can be found
41at src/examples/org/apache/hadoop/examples/DBCountPageview.java.
42</p>
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