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See:
Description
Interface Summary | |
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DBWritable | Deprecated. Use DBWritable instead |
Class Summary | |
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DBConfiguration | Deprecated. Use
DBConfiguration instead |
DBInputFormat<T extends DBWritable> | Deprecated. Use DBInputFormat instead. |
DBInputFormat.DBInputSplit | A InputSplit that spans a set of rows |
DBInputFormat.NullDBWritable | A Class that does nothing, implementing DBWritable |
DBOutputFormat<K extends DBWritable,V> | Deprecated. Use org.apache.hadoop.mapreduce.lib.db.DBOutputFormat instead |
This package contains a library to read records from a database as an input to a mapreduce job, and write the output records to the database.
The Database to access can be configured using the static methods in the DBConfiguration class. Jobs reading input from a database should use DBInputFormat#setInput() to set the configuration. And jobs writing its output to the database should use DBOutputFormat#setOutput().
Tuples from/to the database are converted to/from Java objects using DBWritable methods. Typically, for each table in the db, a class extending DBWritable is defined, which holds the fields of the tuple. The fields of a record are read from the database using DBWritable#readFields(ResultSet), and written to the database using DBWritable#write(PreparedStatament statement).
An example program using both DBInputFormat and DBOutputFormat can be found at src/examples/org/apache/hadoop/examples/DBCountPageview.java.
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