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7IndexUpdateReducer (Hadoop 0.20.1 API)
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91org.apache.hadoop.contrib.index.mapred</FONT>
92<BR>
93Class IndexUpdateReducer</H2>
94<PRE>
95<A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">java.lang.Object</A>
96  <IMG SRC="../../../../../../resources/inherit.gif" ALT="extended by "><A HREF="../../../../../../org/apache/hadoop/mapred/MapReduceBase.html" title="class in org.apache.hadoop.mapred">org.apache.hadoop.mapred.MapReduceBase</A>
97      <IMG SRC="../../../../../../resources/inherit.gif" ALT="extended by "><B>org.apache.hadoop.contrib.index.mapred.IndexUpdateReducer</B>
98</PRE>
99<DL>
100<DT><B>All Implemented Interfaces:</B> <DD><A HREF="http://java.sun.com/javase/6/docs/api/java/io/Closeable.html?is-external=true" title="class or interface in java.io">Closeable</A>, <A HREF="../../../../../../org/apache/hadoop/mapred/JobConfigurable.html" title="interface in org.apache.hadoop.mapred">JobConfigurable</A>, <A HREF="../../../../../../org/apache/hadoop/mapred/Reducer.html" title="interface in org.apache.hadoop.mapred">Reducer</A>&lt;<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/Shard.html" title="class in org.apache.hadoop.contrib.index.mapred">Shard</A>,<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IntermediateForm.html" title="class in org.apache.hadoop.contrib.index.mapred">IntermediateForm</A>,<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/Shard.html" title="class in org.apache.hadoop.contrib.index.mapred">Shard</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;</DD>
101</DL>
102<HR>
103<DL>
104<DT><PRE>public class <B>IndexUpdateReducer</B><DT>extends <A HREF="../../../../../../org/apache/hadoop/mapred/MapReduceBase.html" title="class in org.apache.hadoop.mapred">MapReduceBase</A><DT>implements <A HREF="../../../../../../org/apache/hadoop/mapred/Reducer.html" title="interface in org.apache.hadoop.mapred">Reducer</A>&lt;<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/Shard.html" title="class in org.apache.hadoop.contrib.index.mapred">Shard</A>,<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IntermediateForm.html" title="class in org.apache.hadoop.contrib.index.mapred">IntermediateForm</A>,<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/Shard.html" title="class in org.apache.hadoop.contrib.index.mapred">Shard</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;</DL>
105</PRE>
106
107<P>
108This reducer applies to a shard the changes for it. A "new version" of
109 a shard is created at the end of a reduce. It is important to note that
110 the new version of the shard is not derived from scratch. By leveraging
111 Lucene's update algorithm, the new version of each Lucene instance will
112 share as many files as possible as the previous version.
113<P>
114
115<P>
116<HR>
117
118<P>
119
120<!-- ======== CONSTRUCTOR SUMMARY ======== -->
121
122<A NAME="constructor_summary"><!-- --></A>
123<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
124<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
125<TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2">
126<B>Constructor Summary</B></FONT></TH>
127</TR>
128<TR BGCOLOR="white" CLASS="TableRowColor">
129<TD><CODE><B><A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IndexUpdateReducer.html#IndexUpdateReducer()">IndexUpdateReducer</A></B>()</CODE>
130
131<BR>
132&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</TD>
133</TR>
134</TABLE>
135&nbsp;
136<!-- ========== METHOD SUMMARY =========== -->
137
138<A NAME="method_summary"><!-- --></A>
139<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
140<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
141<TH ALIGN="left" COLSPAN="2"><FONT SIZE="+2">
142<B>Method Summary</B></FONT></TH>
143</TR>
144<TR BGCOLOR="white" CLASS="TableRowColor">
145<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
146<CODE>&nbsp;void</CODE></FONT></TD>
147<TD><CODE><B><A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IndexUpdateReducer.html#close()">close</A></B>()</CODE>
148
149<BR>
150&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Default implementation that does nothing.</TD>
151</TR>
152<TR BGCOLOR="white" CLASS="TableRowColor">
153<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
154<CODE>&nbsp;void</CODE></FONT></TD>
155<TD><CODE><B><A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IndexUpdateReducer.html#configure(org.apache.hadoop.mapred.JobConf)">configure</A></B>(<A HREF="../../../../../../org/apache/hadoop/mapred/JobConf.html" title="class in org.apache.hadoop.mapred">JobConf</A>&nbsp;job)</CODE>
156
157<BR>
158&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Default implementation that does nothing.</TD>
159</TR>
160<TR BGCOLOR="white" CLASS="TableRowColor">
161<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
162<CODE>static&nbsp;<A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Class.html?is-external=true" title="class or interface in java.lang">Class</A>&lt;? extends <A HREF="../../../../../../org/apache/hadoop/io/WritableComparable.html" title="interface in org.apache.hadoop.io">WritableComparable</A>&gt;</CODE></FONT></TD>
163<TD><CODE><B><A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IndexUpdateReducer.html#getOutputKeyClass()">getOutputKeyClass</A></B>()</CODE>
164
165<BR>
166&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Get the reduce output key class.</TD>
167</TR>
168<TR BGCOLOR="white" CLASS="TableRowColor">
169<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
170<CODE>static&nbsp;<A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Class.html?is-external=true" title="class or interface in java.lang">Class</A>&lt;? extends <A HREF="../../../../../../org/apache/hadoop/io/Writable.html" title="interface in org.apache.hadoop.io">Writable</A>&gt;</CODE></FONT></TD>
171<TD><CODE><B><A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IndexUpdateReducer.html#getOutputValueClass()">getOutputValueClass</A></B>()</CODE>
172
173<BR>
174&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Get the reduce output value class.</TD>
175</TR>
176<TR BGCOLOR="white" CLASS="TableRowColor">
177<TD ALIGN="right" VALIGN="top" WIDTH="1%"><FONT SIZE="-1">
178<CODE>&nbsp;void</CODE></FONT></TD>
179<TD><CODE><B><A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IndexUpdateReducer.html#reduce(org.apache.hadoop.contrib.index.mapred.Shard, java.util.Iterator, org.apache.hadoop.mapred.OutputCollector, org.apache.hadoop.mapred.Reporter)">reduce</A></B>(<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/Shard.html" title="class in org.apache.hadoop.contrib.index.mapred">Shard</A>&nbsp;key,
180       <A HREF="http://java.sun.com/javase/6/docs/api/java/util/Iterator.html?is-external=true" title="class or interface in java.util">Iterator</A>&lt;<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IntermediateForm.html" title="class in org.apache.hadoop.contrib.index.mapred">IntermediateForm</A>&gt;&nbsp;values,
181       <A HREF="../../../../../../org/apache/hadoop/mapred/OutputCollector.html" title="interface in org.apache.hadoop.mapred">OutputCollector</A>&lt;<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/Shard.html" title="class in org.apache.hadoop.contrib.index.mapred">Shard</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;&nbsp;output,
182       <A HREF="../../../../../../org/apache/hadoop/mapred/Reporter.html" title="interface in org.apache.hadoop.mapred">Reporter</A>&nbsp;reporter)</CODE>
183
184<BR>
185&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;<i>Reduces</i> values for a given key.</TD>
186</TR>
187</TABLE>
188&nbsp;<A NAME="methods_inherited_from_class_java.lang.Object"><!-- --></A>
189<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
190<TR BGCOLOR="#EEEEFF" CLASS="TableSubHeadingColor">
191<TH ALIGN="left"><B>Methods inherited from class java.lang.<A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true" title="class or interface in java.lang">Object</A></B></TH>
192</TR>
193<TR BGCOLOR="white" CLASS="TableRowColor">
194<TD><CODE><A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#clone()" title="class or interface in java.lang">clone</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#equals(java.lang.Object)" title="class or interface in java.lang">equals</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#finalize()" title="class or interface in java.lang">finalize</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#getClass()" title="class or interface in java.lang">getClass</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#hashCode()" title="class or interface in java.lang">hashCode</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#notify()" title="class or interface in java.lang">notify</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#notifyAll()" title="class or interface in java.lang">notifyAll</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#toString()" title="class or interface in java.lang">toString</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait()" title="class or interface in java.lang">wait</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait(long)" title="class or interface in java.lang">wait</A>, <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Object.html?is-external=true#wait(long, int)" title="class or interface in java.lang">wait</A></CODE></TD>
195</TR>
196</TABLE>
197&nbsp;
198<P>
199
200<!-- ========= CONSTRUCTOR DETAIL ======== -->
201
202<A NAME="constructor_detail"><!-- --></A>
203<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
204<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
205<TH ALIGN="left" COLSPAN="1"><FONT SIZE="+2">
206<B>Constructor Detail</B></FONT></TH>
207</TR>
208</TABLE>
209
210<A NAME="IndexUpdateReducer()"><!-- --></A><H3>
211IndexUpdateReducer</H3>
212<PRE>
213public <B>IndexUpdateReducer</B>()</PRE>
214<DL>
215</DL>
216
217<!-- ============ METHOD DETAIL ========== -->
218
219<A NAME="method_detail"><!-- --></A>
220<TABLE BORDER="1" WIDTH="100%" CELLPADDING="3" CELLSPACING="0" SUMMARY="">
221<TR BGCOLOR="#CCCCFF" CLASS="TableHeadingColor">
222<TH ALIGN="left" COLSPAN="1"><FONT SIZE="+2">
223<B>Method Detail</B></FONT></TH>
224</TR>
225</TABLE>
226
227<A NAME="getOutputKeyClass()"><!-- --></A><H3>
228getOutputKeyClass</H3>
229<PRE>
230public static <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Class.html?is-external=true" title="class or interface in java.lang">Class</A>&lt;? extends <A HREF="../../../../../../org/apache/hadoop/io/WritableComparable.html" title="interface in org.apache.hadoop.io">WritableComparable</A>&gt; <B>getOutputKeyClass</B>()</PRE>
231<DL>
232<DD>Get the reduce output key class.
233<P>
234<DD><DL>
235</DL>
236</DD>
237<DD><DL>
238
239<DT><B>Returns:</B><DD>the reduce output key class</DL>
240</DD>
241</DL>
242<HR>
243
244<A NAME="getOutputValueClass()"><!-- --></A><H3>
245getOutputValueClass</H3>
246<PRE>
247public static <A HREF="http://java.sun.com/javase/6/docs/api/java/lang/Class.html?is-external=true" title="class or interface in java.lang">Class</A>&lt;? extends <A HREF="../../../../../../org/apache/hadoop/io/Writable.html" title="interface in org.apache.hadoop.io">Writable</A>&gt; <B>getOutputValueClass</B>()</PRE>
248<DL>
249<DD>Get the reduce output value class.
250<P>
251<DD><DL>
252</DL>
253</DD>
254<DD><DL>
255
256<DT><B>Returns:</B><DD>the reduce output value class</DL>
257</DD>
258</DL>
259<HR>
260
261<A NAME="reduce(org.apache.hadoop.contrib.index.mapred.Shard, java.util.Iterator, org.apache.hadoop.mapred.OutputCollector, org.apache.hadoop.mapred.Reporter)"><!-- --></A><H3>
262reduce</H3>
263<PRE>
264public void <B>reduce</B>(<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/Shard.html" title="class in org.apache.hadoop.contrib.index.mapred">Shard</A>&nbsp;key,
265                   <A HREF="http://java.sun.com/javase/6/docs/api/java/util/Iterator.html?is-external=true" title="class or interface in java.util">Iterator</A>&lt;<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IntermediateForm.html" title="class in org.apache.hadoop.contrib.index.mapred">IntermediateForm</A>&gt;&nbsp;values,
266                   <A HREF="../../../../../../org/apache/hadoop/mapred/OutputCollector.html" title="interface in org.apache.hadoop.mapred">OutputCollector</A>&lt;<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/Shard.html" title="class in org.apache.hadoop.contrib.index.mapred">Shard</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;&nbsp;output,
267                   <A HREF="../../../../../../org/apache/hadoop/mapred/Reporter.html" title="interface in org.apache.hadoop.mapred">Reporter</A>&nbsp;reporter)
268            throws <A HREF="http://java.sun.com/javase/6/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</A></PRE>
269<DL>
270<DD><B>Description copied from interface: <CODE><A HREF="../../../../../../org/apache/hadoop/mapred/Reducer.html#reduce(K2, java.util.Iterator, org.apache.hadoop.mapred.OutputCollector, org.apache.hadoop.mapred.Reporter)">Reducer</A></CODE></B></DD>
271<DD><i>Reduces</i> values for a given key. 
272 
273 <p>The framework calls this method for each
274 <code>&lt;key, (list of values)></code> pair in the grouped inputs.
275 Output values must be of the same type as input values.  Input keys must
276 not be altered. The framework will <b>reuse</b> the key and value objects
277 that are passed into the reduce, therefore the application should clone
278 the objects they want to keep a copy of. In many cases, all values are
279 combined into zero or one value.
280 </p>
281   
282 <p>Output pairs are collected with calls to 
283 <A HREF="../../../../../../org/apache/hadoop/mapred/OutputCollector.html#collect(K, V)"><CODE>OutputCollector.collect(Object,Object)</CODE></A>.</p>
284
285 <p>Applications can use the <A HREF="../../../../../../org/apache/hadoop/mapred/Reporter.html" title="interface in org.apache.hadoop.mapred"><CODE>Reporter</CODE></A> provided to report progress
286 or just indicate that they are alive. In scenarios where the application
287 takes an insignificant amount of time to process individual key/value
288 pairs, this is crucial since the framework might assume that the task has
289 timed-out and kill that task. The other way of avoiding this is to set
290 <a href="../../../../../../../mapred-default.html#mapred.task.timeout">
291 mapred.task.timeout</a> to a high-enough value (or even zero for no
292 time-outs).</p>
293<P>
294<DD><DL>
295<DT><B>Specified by:</B><DD><CODE><A HREF="../../../../../../org/apache/hadoop/mapred/Reducer.html#reduce(K2, java.util.Iterator, org.apache.hadoop.mapred.OutputCollector, org.apache.hadoop.mapred.Reporter)">reduce</A></CODE> in interface <CODE><A HREF="../../../../../../org/apache/hadoop/mapred/Reducer.html" title="interface in org.apache.hadoop.mapred">Reducer</A>&lt;<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/Shard.html" title="class in org.apache.hadoop.contrib.index.mapred">Shard</A>,<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/IntermediateForm.html" title="class in org.apache.hadoop.contrib.index.mapred">IntermediateForm</A>,<A HREF="../../../../../../org/apache/hadoop/contrib/index/mapred/Shard.html" title="class in org.apache.hadoop.contrib.index.mapred">Shard</A>,<A HREF="../../../../../../org/apache/hadoop/io/Text.html" title="class in org.apache.hadoop.io">Text</A>&gt;</CODE></DL>
296</DD>
297<DD><DL>
298<DT><B>Parameters:</B><DD><CODE>key</CODE> - the key.<DD><CODE>values</CODE> - the list of values to reduce.<DD><CODE>output</CODE> - to collect keys and combined values.<DD><CODE>reporter</CODE> - facility to report progress.
299<DT><B>Throws:</B>
300<DD><CODE><A HREF="http://java.sun.com/javase/6/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</A></CODE></DL>
301</DD>
302</DL>
303<HR>
304
305<A NAME="configure(org.apache.hadoop.mapred.JobConf)"><!-- --></A><H3>
306configure</H3>
307<PRE>
308public void <B>configure</B>(<A HREF="../../../../../../org/apache/hadoop/mapred/JobConf.html" title="class in org.apache.hadoop.mapred">JobConf</A>&nbsp;job)</PRE>
309<DL>
310<DD><B>Description copied from class: <CODE><A HREF="../../../../../../org/apache/hadoop/mapred/MapReduceBase.html#configure(org.apache.hadoop.mapred.JobConf)">MapReduceBase</A></CODE></B></DD>
311<DD>Default implementation that does nothing.
312<P>
313<DD><DL>
314<DT><B>Specified by:</B><DD><CODE><A HREF="../../../../../../org/apache/hadoop/mapred/JobConfigurable.html#configure(org.apache.hadoop.mapred.JobConf)">configure</A></CODE> in interface <CODE><A HREF="../../../../../../org/apache/hadoop/mapred/JobConfigurable.html" title="interface in org.apache.hadoop.mapred">JobConfigurable</A></CODE><DT><B>Overrides:</B><DD><CODE><A HREF="../../../../../../org/apache/hadoop/mapred/MapReduceBase.html#configure(org.apache.hadoop.mapred.JobConf)">configure</A></CODE> in class <CODE><A HREF="../../../../../../org/apache/hadoop/mapred/MapReduceBase.html" title="class in org.apache.hadoop.mapred">MapReduceBase</A></CODE></DL>
315</DD>
316<DD><DL>
317<DT><B>Parameters:</B><DD><CODE>job</CODE> - the configuration</DL>
318</DD>
319</DL>
320<HR>
321
322<A NAME="close()"><!-- --></A><H3>
323close</H3>
324<PRE>
325public void <B>close</B>()
326           throws <A HREF="http://java.sun.com/javase/6/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</A></PRE>
327<DL>
328<DD><B>Description copied from class: <CODE><A HREF="../../../../../../org/apache/hadoop/mapred/MapReduceBase.html#close()">MapReduceBase</A></CODE></B></DD>
329<DD>Default implementation that does nothing.
330<P>
331<DD><DL>
332<DT><B>Specified by:</B><DD><CODE><A HREF="http://java.sun.com/javase/6/docs/api/java/io/Closeable.html?is-external=true#close()" title="class or interface in java.io">close</A></CODE> in interface <CODE><A HREF="http://java.sun.com/javase/6/docs/api/java/io/Closeable.html?is-external=true" title="class or interface in java.io">Closeable</A></CODE><DT><B>Overrides:</B><DD><CODE><A HREF="../../../../../../org/apache/hadoop/mapred/MapReduceBase.html#close()">close</A></CODE> in class <CODE><A HREF="../../../../../../org/apache/hadoop/mapred/MapReduceBase.html" title="class in org.apache.hadoop.mapred">MapReduceBase</A></CODE></DL>
333</DD>
334<DD><DL>
335
336<DT><B>Throws:</B>
337<DD><CODE><A HREF="http://java.sun.com/javase/6/docs/api/java/io/IOException.html?is-external=true" title="class or interface in java.io">IOException</A></CODE></DL>
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