Package org.apache.lucene.search

Class IndexSearcher

java.lang.Object
org.apache.lucene.search.IndexSearcher
Direct Known Subclasses:
SuggestIndexSearcher
public class IndexSearcher extends Object
Implements search over a single IndexReader.

Applications usually need only call the inherited search(Query,int) method. For performance reasons, if your index is unchanging, you should share a single IndexSearcher instance across multiple searches instead of creating a new one per-search. If your index has changed and you wish to see the changes reflected in searching, you should use DirectoryReader.openIfChanged(DirectoryReader) to obtain a new reader and then create a new IndexSearcher from that. Also, for low-latency turnaround it's best to use a near-real-time reader (DirectoryReader.open(IndexWriter)). Once you have a new IndexReader, it's relatively cheap to create a new IndexSearcher from it.

NOTE: The search(org.apache.lucene.search.Query, int) and searchAfter(org.apache.lucene.search.ScoreDoc, org.apache.lucene.search.Query, int) methods are configured to only count top hits accurately up to 1,000 and may return a lower bound of the hit count if the hit count is greater than or equal to 1,000. On queries that match lots of documents, counting the number of hits may take much longer than computing the top hits so this trade-off allows to get some minimal information about the hit count without slowing down search too much. The TopDocs.scoreDocs array is always accurate however. If this behavior doesn't suit your needs, you should create collectors manually with either TopScoreDocCollector.create(int, int) or TopFieldCollector.create(org.apache.lucene.search.Sort, int, int) and call search(Query, Collector).

NOTE: IndexSearcher instances are completely thread safe, meaning multiple threads can call any of its methods, concurrently. If your application requires external synchronization, you should not synchronize on the IndexSearcher instance; use your own (non-Lucene) objects instead.