package com.bigdata.search;
import org.apache.log4j.Logger;
import com.bigdata.btree.IRangeQuery;
import com.bigdata.btree.ISimpleSplitHandler;
import com.bigdata.btree.keys.IKeyBuilder;
import com.bigdata.btree.keys.SuccessorUtil;
import com.bigdata.util.BytesUtil;
/**
* Procedure reads on the terms index, aggregating data on a per-{@link Hit}
* basis.
* <p>
* The procedure uses an {@link IRangeQuery#rangeIterator(byte[], byte[])} to
* perform a key range scan for a specific term. The range iterator will
* automatically issue queries, obtaining a "chunk" of results at a time. Those
* results are aggregated on the {@link Hit} collection, which is maintained in
* a thread-safe hash map.
* <p>
* Note: An {@link ISimpleSplitHandler} imposes the constraint that index
* partitions may only fall on a term boundary, hence all tuples for any given
* term will always be found on the same index partition.
*
* @param <V>
* The generic type of the document identifier.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id: CountIndexTask.java 6018 2012-02-13 09:48:15Z mrpersonick $
*/
public class CountIndexTask<V extends Comparable<V>> extends AbstractIndexTask<V> {
final private static Logger log = Logger.getLogger(CountIndexTask.class);
private final long rangeCount;
/**
* Setup a task that will perform a range scan for entries matching the
* search term.
*
* @param termText
* The term text for the search term.
* @param termNdx
* The index of this term within the overall search.
* @param numTerms
* The overall number of search terms.
* @param prefixMatch
* When <code>true</code> any term having <i>termText</i> as a
* prefix will be matched. Otherwise the term must be an exact
* match for the <i>termText</i>.
* @param queryTermWeight
* The weight for the search term.
* @param searchEngine
* The search engine.
*/
public CountIndexTask(final String termText, final int termNdx, final int numTerms,
final boolean prefixMatch,
final double queryTermWeight, final FullTextIndex<V> searchEngine) {
super(termText, termNdx, numTerms, prefixMatch, queryTermWeight, searchEngine);
if (log.isDebugEnabled())
log.debug("termText=[" + termText + "], prefixMatch=" + prefixMatch
+ ", queryTermWeight=" + queryTermWeight + "\nfromKey="
+ BytesUtil.toString(fromKey) + "\n toKey="
+ BytesUtil.toString(toKey));
rangeCount = searchEngine.getIndex().rangeCount(fromKey, toKey);
}
/**
* Return the range count for this task.
*/
public long getRangeCount() {
return rangeCount;
}
}