# Uses of Class
org.apache.lucene.index.IndexReader

Packages that use IndexReader
Package
Description
org.apache.lucene.index
Code to maintain and access indices.
org.apache.lucene.search
Code to search indices.
org.apache.lucene.util.hnsw
Navigable Small-World graph, nominally Hierarchical but currently only has a single layer.

- ## Uses of IndexReader in org.apache.lucene.index

  Classes in org.apache.lucene.index with type parameters of type IndexReader
  Modifier and Type
  Class
  Description
  `class`
  `BaseCompositeReader<R extends IndexReader>`
  Base class for implementing `CompositeReader`s based on an array of sub-readers.
  Subclasses of IndexReader in org.apache.lucene.index
  Modifier and Type
  Class
  Description
  `class`
  `BaseCompositeReader<R extends IndexReader>`
  Base class for implementing `CompositeReader`s based on an array of sub-readers.
  `class`
  `CodecReader`
  LeafReader implemented by codec APIs.
  `class`
  `CompositeReader`
  Instances of this reader type can only be used to get stored fields from the underlying LeafReaders, but it is not possible to directly retrieve postings.
  `class`
  `DirectoryReader`
  DirectoryReader is an implementation of `CompositeReader` that can read indexes in a `Directory`.
  `class`
  `ExitableDirectoryReader`
  The `ExitableDirectoryReader` wraps a real index `DirectoryReader` and allows for a `QueryTimeout` implementation object to be checked periodically to see if the thread should exit or not.
  `static class`
  `ExitableDirectoryReader.ExitableFilterAtomicReader`
  Wrapper class for another FilterAtomicReader.
  `class`
  `FilterCodecReader`
  A `FilterCodecReader` contains another CodecReader, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality.
  `class`
  `FilterDirectoryReader`
  A FilterDirectoryReader wraps another DirectoryReader, allowing implementations to transform or extend it.
  `class`
  `FilterLeafReader`
  A `FilterLeafReader` contains another LeafReader, which it uses as its basic source of data, possibly transforming the data along the way or providing additional functionality.
  `class`
  `LeafReader`
  `LeafReader` is an abstract class, providing an interface for accessing an index.
  `class`
  `MultiReader`
  A `CompositeReader` which reads multiple indexes, appending their content.
  `class`
  `ParallelCompositeReader`
  An `CompositeReader` which reads multiple, parallel indexes.
  `class`
  `ParallelLeafReader`
  An `LeafReader` which reads multiple, parallel indexes.
  `final class`
  `SegmentReader`
  IndexReader implementation over a single segment.
  `final class`
  `SoftDeletesDirectoryReaderWrapper`
  This reader filters out documents that have a doc values value in the given field and treat these documents as soft deleted.
  `final class`
  `SortingCodecReader`
  An `CodecReader` which supports sorting documents by a given `Sort`.
  `final class`
  `StandardDirectoryReader`
  Default implementation of `DirectoryReader`.
  Methods in org.apache.lucene.index that return IndexReader
  Modifier and Type
  Method
  Description
  `abstract IndexReader`
  IndexReaderContext.`reader()`
  Returns the `IndexReader`, this context represents.
  Methods in org.apache.lucene.index that return types with arguments of type IndexReader
  Modifier and Type
  Method
  Description
  `protected abstract List<? extends IndexReader>`
  CompositeReader.`getSequentialSubReaders()`
  Expert: returns the sequential sub readers that this reader is logically composed of.
  Methods in org.apache.lucene.index with parameters of type IndexReader
  Modifier and Type
  Method
  Description
  `static BinaryDocValues`
  MultiDocValues.`getBinaryValues(IndexReader r, String field)`
  Returns a BinaryDocValues for a reader's docvalues (potentially merging on-the-fly)
  `static int`
  PointValues.`getDocCount(IndexReader reader, String field)`
  Return the cumulated number of docs that have points across all leaves of the given `IndexReader`.
  `static Collection<String>`
  FieldInfos.`getIndexedFields(IndexReader reader)`
  Returns a set of names of fields that have a terms index.
  `static Bits`
  MultiBits.`getLiveDocs(IndexReader reader)`
  Returns a single `Bits` instance for this reader, merging live Documents on the fly.
  `static byte[]`
  PointValues.`getMaxPackedValue(IndexReader reader, String field)`
  Return the maximum packed values across all leaves of the given `IndexReader`.
  `static FieldInfos`
  FieldInfos.`getMergedFieldInfos(IndexReader reader)`
  Call this to get the (merged) FieldInfos for a composite reader.
  `static byte[]`
  PointValues.`getMinPackedValue(IndexReader reader, String field)`
  Return the minimum packed values across all leaves of the given `IndexReader`.
  `static NumericDocValues`
  MultiDocValues.`getNormValues(IndexReader r, String field)`
  Returns a NumericDocValues for a reader's norms (potentially merging on-the-fly).
  `static NumericDocValues`
  MultiDocValues.`getNumericValues(IndexReader r, String field)`
  Returns a NumericDocValues for a reader's docvalues (potentially merging on-the-fly)
  `static SortedNumericDocValues`
  MultiDocValues.`getSortedNumericValues(IndexReader r, String field)`
  Returns a SortedNumericDocValues for a reader's docvalues (potentially merging on-the-fly)
  `static SortedSetDocValues`
  MultiDocValues.`getSortedSetValues(IndexReader r, String field)`
  Returns a SortedSetDocValues for a reader's docvalues (potentially doing extremely slow things).
  `static SortedDocValues`
  MultiDocValues.`getSortedValues(IndexReader r, String field)`
  Returns a SortedDocValues for a reader's docvalues (potentially doing extremely slow things).
  `static PostingsEnum`
  MultiTerms.`getTermPostingsEnum(IndexReader r, String field, BytesRef term)`
  Returns `PostingsEnum` for the specified field and term.
  `static PostingsEnum`
  MultiTerms.`getTermPostingsEnum(IndexReader r, String field, BytesRef term, int flags)`
  Returns `PostingsEnum` for the specified field and term, with control over whether freqs, positions, offsets or payloads are required.
  `static Terms`
  MultiTerms.`getTerms(IndexReader r, String field)`
  This method may return null if the field does not exist or if it has no terms.
  `final void`
  IndexReader.`registerParentReader(IndexReader reader)`
  Expert: This method is called by `IndexReader`s which wrap other readers (e.g.
  `static long`
  PointValues.`size(IndexReader reader, String field)`
  Return the cumulated number of points across all leaves of the given `IndexReader`.
  `long`
  IndexWriter.`tryDeleteDocument(IndexReader readerIn, int docID)`
  Expert: attempts to delete by document ID, as long as the provided reader is a near-real-time reader (from `DirectoryReader.open(IndexWriter)`).
  `long`
  IndexWriter.`tryUpdateDocValue(IndexReader readerIn, int docID, Field... fields)`
  Expert: attempts to update doc values by document ID, as long as the provided reader is a near-real-time reader (from `DirectoryReader.open(IndexWriter)`).
  Constructors in org.apache.lucene.index with parameters of type IndexReader
  Modifier
  Constructor
  Description
  `protected`
  `BaseCompositeReader(R[] subReaders, Comparator<R> subReadersSorter)`
  Constructs a `BaseCompositeReader` on the given subReaders.
  ``
  `MultiReader(IndexReader... subReaders)`
  Construct a MultiReader aggregating the named set of (sub)readers.
  ``
  `MultiReader(IndexReader[] subReaders, boolean closeSubReaders)`
  Construct a MultiReader aggregating the named set of (sub)readers.
  ``
  `MultiReader(IndexReader[] subReaders, Comparator<IndexReader> subReadersSorter, boolean closeSubReaders)`
  Construct a MultiReader aggregating the named set of (sub)readers.
  Constructor parameters in org.apache.lucene.index with type arguments of type IndexReader
  Modifier
  Constructor
  Description
  ``
  `MultiReader(IndexReader[] subReaders, Comparator<IndexReader> subReadersSorter, boolean closeSubReaders)`
  Construct a MultiReader aggregating the named set of (sub)readers.

- ## Uses of IndexReader in org.apache.lucene.search

  Methods in org.apache.lucene.search that return IndexReader
  Modifier and Type
  Method
  Description
  `IndexReader`
  IndexSearcher.`getIndexReader()`
  Return the `IndexReader` this searches.
  Methods in org.apache.lucene.search with parameters of type IndexReader
  Modifier and Type
  Method
  Description
  `static IndexSearcher`
  SearcherManager.`getSearcher(SearcherFactory searcherFactory, IndexReader reader, IndexReader previousReader)`
  Expert: creates a searcher from the provided `IndexReader` using the provided `SearcherFactory`.
  `IndexSearcher`
  SearcherFactory.`newSearcher(IndexReader reader, IndexReader previousReader)`
  Returns a new IndexSearcher over the given reader.
  Constructors in org.apache.lucene.search with parameters of type IndexReader
  Modifier
  Constructor
  Description
  ``
  `IndexSearcher(IndexReader r)`
  Creates a searcher searching the provided index.
  ``
  `IndexSearcher(IndexReader r, Executor executor)`
  Runs searches for each segment separately, using the provided Executor.

- ## Uses of IndexReader in org.apache.lucene.util.hnsw

  Methods in org.apache.lucene.util.hnsw with parameters of type IndexReader
  Modifier and Type
  Method
  Description
  `static boolean`
  HnswUtil.`graphIsRooted(IndexReader reader, String vectorField)`
  In graph theory, "connected components" are really defined only for undirected (ie bidirectional) graphs.