org.apache.hadoop.hive.contrib.genericudf.example

Class GenericUDFDBOutput

java.lang.Object

org.apache.hadoop.hive.ql.udf.generic.GenericUDF

org.apache.hadoop.hive.contrib.genericudf.example.GenericUDFDBOutput

All Implemented Interfaces:

Closeable, AutoCloseable

public class GenericUDFDBOutput
extends GenericUDF

GenericUDFDBOutput is designed to output data directly from Hive to a JDBC datastore. This UDF is useful for exporting small to medium summaries that have a unique key. Due to the nature of hadoop, individual mappers, reducers or entire jobs can fail. If a failure occurs a mapper or reducer may be retried. This UDF has no way of detecting failures or rolling back a transaction. Consequently, you should only only use this to export to a table with a unique key. The unique key should safeguard against duplicate data. Use hive's ADD JAR feature to add your JDBC Driver to the distributed cache, otherwise GenericUDFDBoutput will fail.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.hive.ql.udf.generic.GenericUDF

GenericUDF.DeferredJavaObject, GenericUDF.DeferredObject

Constructor Summary

Constructors

Constructor and Description
GenericUDFDBOutput()

Method Summary

Modifier and Type	Method and Description
Object	evaluate(GenericUDF.DeferredObject[] arguments) Evaluate the GenericUDF with the arguments.
String	getDisplayString(String[] children) Get the String to be displayed in explain.
ObjectInspector	initialize(ObjectInspector[] arguments) Initialize this GenericUDF.

Methods inherited from class org.apache.hadoop.hive.ql.udf.generic.GenericUDF

checkArgGroups, checkArgPrimitive, checkArgsSize, close, configure, copyToNewInstance, flip, getArgOrder, getConstantBooleanValue, getConstantIntValue, getConstantStringValue, getDateValue, getDoubleValue, getFuncName, getIntValue, getLongValue, getRequiredFiles, getRequiredJars, getStandardDisplayString, getStandardDisplayString, getStringValue, getTimestampValue, getUdfName, initializeAndFoldConstants, negative, obtainDateConverter, obtainDoubleConverter, obtainIntConverter, obtainLongConverter, obtainStringConverter, obtainTimestampConverter

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

GenericUDFDBOutput

public GenericUDFDBOutput()

Method Detail

initialize

public ObjectInspector initialize(ObjectInspector[] arguments)
                           throws UDFArgumentTypeException

Description copied from class: GenericUDF

Initialize this GenericUDF. This will be called once and only once per GenericUDF instance.

Specified by:

initialize in class GenericUDF

Parameters:

arguments - argument 0 is the JDBC connection string argument 1 is the user name argument 2 is the password argument 3 is an SQL query to be used in the PreparedStatement argument (4-n) The remaining arguments must be primitive and are passed to the PreparedStatement object

Returns:

The ObjectInspector for the return value

Throws:

UDFArgumentTypeException

evaluate

public Object evaluate(GenericUDF.DeferredObject[] arguments)
                throws HiveException

Description copied from class: GenericUDF

Evaluate the GenericUDF with the arguments.

Specified by:

evaluate in class GenericUDF

Parameters:

arguments - The arguments as DeferedObject, use DeferedObject.get() to get the actual argument Object. The Objects can be inspected by the ObjectInspectors passed in the initialize call.

Returns:

0 on success -1 on failure

Throws:

HiveException

getDisplayString

public String getDisplayString(String[] children)

Description copied from class: GenericUDF

Get the String to be displayed in explain.

Specified by:

getDisplayString in class GenericUDF