Package org.apache.lucene.search

Class IndexOrDocValuesQuery

  • public final class IndexOrDocValuesQuery
extends Query
    A query that uses either an index structure (points or terms) or doc values in order to run a query, depending which one is more efficient. This is typically useful for range queries, whose Weight.scorer(org.apache.lucene.index.LeafReaderContext) is costly to create since it usually needs to sort large lists of doc ids. For instance, for a field that both indexed LongPoints and SortedNumericDocValuesFields with the same values, an efficient range query could be created by doing: 
       String field;
   long minValue, maxValue;
   Query pointQuery = LongPoint.newRangeQuery(field, minValue, maxValue);
   Query dvQuery = SortedNumericDocValuesField.newSlowRangeQuery(field, minValue, maxValue);
   Query query = new IndexOrDocValuesQuery(pointQuery, dvQuery);
    The above query will be efficient as it will use points in the case that they perform better, ie. when we need a good lead iterator that will be almost entirely consumed; and doc values otherwise, ie. in the case that another part of the query is already leading iteration but we still need the ability to verify that some documents match.

    NOTEThis query currently only works well with point range/exact queries and their equivalent doc values queries.

    WARNING: This API is experimental and might change in incompatible ways in the next release.

    • Constructor Detail

      • IndexOrDocValuesQuery

        public IndexOrDocValuesQuery​(Query indexQuery,
                             Query dvQuery)
        Create an IndexOrDocValuesQuery. Both provided queries must match the same documents and give the same scores.
        Parameters:
        indexQuery - a query that has a good iterator but whose scorer may be costly to create
        dvQuery - a query whose scorer is cheap to create that can quickly check whether a given document matches

    • Method Detail

      • getIndexQuery

        public Query getIndexQuery()
        Return the wrapped query that may be costly to initialize but has a good iterator.

      • getRandomAccessQuery

        public Query getRandomAccessQuery()
        Return the wrapped query that may be slow at identifying all matching documents, but which is cheap to initialize and can efficiently verify that some documents match.

      • toString

        public String toString​(String field)
        Description copied from class: Query
        Prints a query to a string, with field assumed to be the default field and omitted.
        Specified by:
        toString in class Query

      • equals

        public boolean equals​(Object obj)
        Description copied from class: Query
        Override and implement query instance equivalence properly in a subclass. This is required so that QueryCache works properly. Typically a query will be equal to another only if it's an instance of the same class and its document-filtering properties are identical that other instance. Utility methods are provided for certain repetitive code.
        Specified by:
        equals in class Query
        See Also:
        Query.sameClassAs(Object), Query.classHash()

      • hashCode

        public int hashCode()
        Description copied from class: Query
        Override and implement query hash code properly in a subclass. This is required so that QueryCache works properly.
        Specified by:
        hashCode in class Query
        See Also:
        Query.equals(Object)

      • rewrite

        public Query rewrite​(IndexReader reader)
              throws IOException
        Description copied from class: Query
        Expert: called to re-write queries into primitive queries. For example, a PrefixQuery will be rewritten into a BooleanQuery that consists of TermQuerys.
        Overrides:
        rewrite in class Query
        Throws:
        IOException

      • createWeight

        public Weight createWeight​(IndexSearcher searcher,
                           boolean needsScores,
                           float boost)
                    throws IOException
        Description copied from class: Query
        Expert: Constructs an appropriate Weight implementation for this query.

        Only implemented by primitive queries, which re-write to themselves.

        Overrides:
        createWeight in class Query
        needsScores - True if document scores (Scorer.score()) are needed.
        boost - The boost that is propagated by the parent queries.
        Throws:
        IOException