The Neo4j Manual v3.1.0-SNAPSHOT34.11. Extra features for Lucene indexes

Lucene supports smart indexing of numbers, querying for ranges and sorting such results, and so does its backend for Neo4j. To mark a value so that it is indexed as a numeric value, we can make use of the ValueContext class, like this:

movies.add( theMatrix, "year-numeric", new ValueContext( 1999 ).indexNumeric() );
movies.add( theMatrixReloaded, "year-numeric", new ValueContext( 2003 ).indexNumeric() );
movies.add( malena, "year-numeric", new ValueContext( 2000 ).indexNumeric() );

int from = 1997;
int to = 1999;
hits = movies.query( QueryContext.numericRange( "year-numeric", from, to ) );

Note The same type must be used for indexing and querying. That is, you can’t index a value as a Long and then query the index using an Integer.

By giving null as from/to argument, an open ended query is created. In the following example we are doing that, and have added sorting to the query as well:

hits = movies.query(
        QueryContext.numericRange( "year-numeric", from, null )
                .sortNumeric( "year-numeric", false ) );

From/to in the ranges defaults to be inclusive, but you can change this behavior by using two extra parameters:

movies.add( theMatrix, "score", new ValueContext( 8.7 ).indexNumeric() );
movies.add( theMatrixReloaded, "score", new ValueContext( 7.1 ).indexNumeric() );
movies.add( malena, "score", new ValueContext( 7.4 ).indexNumeric() );

// include 8.0, exclude 9.0
hits = movies.query( QueryContext.numericRange( "score", 8.0, 9.0, true, false ) );

Lucene performs sorting very well, and that is also exposed in the index backend, through the QueryContext class:

hits = movies.query( "title", new QueryContext( "*" ).sort( "title" ) );
for ( Node hit : hits )
{
    // all movies with a title in the index, ordered by title
}
// or
hits = movies.query( new QueryContext( "title:*" ).sort( "year", "title" ) );
for ( Node hit : hits )
{
    // all movies with a title in the index, ordered by year, then title
}

We sort the results by relevance (score) like this:

hits = movies.query( "title", new QueryContext( "The*" ).sortByScore() );
for ( Node movie : hits )
{
    // hits sorted by relevance (score)
}

Instead of passing in Lucene query syntax queries, you can instantiate such queries programmatically and pass in as argument, for example:

// a TermQuery will give exact matches
Node actor = actors.query( new TermQuery( new Term( "name", "Keanu Reeves" ) ) ).getSingle();

Note that the TermQuery is basically the same thing as using the get method on the index.

This is how to perform wildcard searches using Lucene query objects:

hits = movies.query( new WildcardQuery( new Term( "title", "The Matrix*" ) ) );
for ( Node movie : hits )
{
    System.out.println( movie.getProperty( "title" ) );
}

Note that this allows for whitespace in the search string.

Lucene supports querying for multiple terms in the same query, like so:

hits = movies.query( "title:*Matrix* AND year:1999" );

Caution Compound queries can’t search across committed index entries and those who haven’t got committed yet at the same time.

The default operator (that is whether AND or OR is used in between different terms) in a query is OR. Changing that behavior is also done via the QueryContext class:

QueryContext query = new QueryContext( "title:*Matrix* year:1999" )
        .defaultOperator( Operator.AND );
hits = movies.query( query );