Paginating Lucene Search Results

Paginating Lucene Search Results

As we can see in the Lucene FAQ, the Lucene developers recommended approach topagination is re-executing the search and navigating to the correct position in the ScoreDoc array.

As a result, pagination becomes a problem of finding the correct start position and end position in the ScoreDoc array.

Query query = qp.parse(searchTerm);

TopDocs hits = searcher.search(query, maxNumberOfResults);

ArrayLocation arrayLocation = paginator.calculateArrayLocation(hits.scoreDocs.length, pageNumber, pageSize);

 

for (int i = arrayLocation.getStart() - 1; i < arrayLocation.getEnd(); i++) {

    int docId = hits.scoreDocs[i].doc;

 

    Document doc = searcher.doc(docId);

    String filename = doc.get("filename");

    String contents =  doc.get(searchField);

 

}

public class Paginator {

 

    public ArrayLocation calculateArrayLocation(int totalHits, int pageNumber,

        int pageSize) {

        ArrayLocation al = new ArrayLocation();

 

        if (totalHits < 1 || pageNumber < 1 || pageSize < 1) {

            al.setStart(0);

            al.setEnd(0);

            return al;

        }

 

        int start= 1 + (pageNumber -1) * pageSize;

        int end = Math.min(pageNumber * pageSize, totalHits);

        if (start > end) {

            start = Math.max(1, end - pageSize);

        }

 

        al.setStart(start);

        al.setEnd(end);

        return al;

    }

}

Please read full article from Paginating Lucene Search Results