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java.lang.Objectorg.apache.hadoop.mapred.lib.db.DBOutputFormat<K,V>
public class DBOutputFormat<K extends DBWritable,V>
A OutputFormat that sends the reduce output to a SQL table.
DBOutputFormat
accepts <key,value> pairs, where
key has a type extending DBWritable. Returned DBOutputFormat.DBRecordWriter
writes only the key to the database with a batch SQL query.
Nested Class Summary | |
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protected class |
DBOutputFormat.DBRecordWriter
A RecordWriter that writes the reduce output to a SQL table |
Constructor Summary | |
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DBOutputFormat()
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Method Summary | |
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void |
checkOutputSpecs(FileSystem filesystem,
JobConf job)
Check for validity of the output-specification for the job. |
protected String |
constructQuery(String table,
String[] fieldNames)
Constructs the query used as the prepared statement to insert data. |
RecordWriter<K,V> |
getRecordWriter(FileSystem filesystem,
JobConf job,
String name,
Progressable progress)
Get the RecordWriter for the given job. |
static void |
setOutput(JobConf job,
String tableName,
String... fieldNames)
Initializes the reduce-part of the job with the appropriate output settings |
Methods inherited from class java.lang.Object |
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clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Constructor Detail |
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public DBOutputFormat()
Method Detail |
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protected String constructQuery(String table, String[] fieldNames)
public void checkOutputSpecs(FileSystem filesystem, JobConf job) throws IOException
This is to validate the output specification for the job when it is a job is submitted. Typically checks that it does not already exist, throwing an exception when it already exists, so that output is not overwritten.
checkOutputSpecs
in interface OutputFormat<K extends DBWritable,V>
job
- job configuration.
IOException
- when output should not be attemptedpublic RecordWriter<K,V> getRecordWriter(FileSystem filesystem, JobConf job, String name, Progressable progress) throws IOException
RecordWriter
for the given job.
getRecordWriter
in interface OutputFormat<K extends DBWritable,V>
job
- configuration for the job whose output is being written.name
- the unique name for this part of the output.progress
- mechanism for reporting progress while writing to file.
RecordWriter
to write the output for the job.
IOException
public static void setOutput(JobConf job, String tableName, String... fieldNames)
job
- The jobtableName
- The table to insert data intofieldNames
- The field names in the table
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