Package org.apache.lucene.search

Class FilteredDocIdSet

java.lang.Object
org.apache.lucene.search.DocIdSet
org.apache.lucene.search.FilteredDocIdSet
Direct Known Subclasses:
BitsFilteredDocIdSet
public abstract class FilteredDocIdSet extends DocIdSet
Abstract decorator class for a DocIdSet implementation that provides on-demand filtering/validation mechanism on a given DocIdSet.

Technically, this same functionality could be achieved with ChainedFilter (under queries/), however the benefit of this class is it never materializes the full bitset for the filter. Instead, the match(int) method is invoked on-demand, per docID visited during searching. If you know few docIDs will be visited, and the logic behind match(int) is relatively costly, this may be a better way to filter than ChainedFilter.

See Also:

  • Constructor Details

    • FilteredDocIdSet

      public FilteredDocIdSet(DocIdSet innerSet)
      Constructor.
      Parameters:
      innerSet - Underlying DocIdSet

  • Method Details

    • isCacheable

      public boolean isCacheable()
      This DocIdSet implementation is cacheable if the inner set is cacheable.
      Overrides:
      isCacheable in class DocIdSet

    • bits

      public Bits bits() throws IOException
      Description copied from class: DocIdSet
      Optionally provides a Bits interface for random access to matching documents.
      Overrides:
      bits in class DocIdSet
      Returns:
      null, if this DocIdSet does not support random access. In contrast to DocIdSet.iterator(), a return value of null does not imply that no documents match the filter! The default implementation does not provide random access, so you only need to implement this method if your DocIdSet can guarantee random access to every docid in O(1) time without external disk access (as Bits interface cannot throw IOException). This is generally true for bit sets like FixedBitSet, which return itself if they are used as DocIdSet.
      Throws:
      IOException

    • iterator

      public DocIdSetIterator iterator() throws IOException
      Implementation of the contract to build a DocIdSetIterator.
      Specified by:
      iterator in class DocIdSet
      Throws:
      IOException
      See Also: