Class AtomicReader

  • All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable
    Direct Known Subclasses:
    FilterAtomicReader, ParallelAtomicReader, SegmentReader, SlowCompositeReaderWrapper

    public abstract class AtomicReader
    extends IndexReader
    AtomicReader is an abstract class, providing an interface for accessing an index. Search of an index is done entirely through this abstract interface, so that any subclass which implements it is searchable. IndexReaders implemented by this subclass do not consist of several sub-readers, they are atomic. They support retrieval of stored fields, doc values, terms, and postings.

    For efficiency, in this API documents are often referred to via document numbers, non-negative integers which each name a unique document in the index. These document numbers are ephemeral -- they may change as documents are added to and deleted from an index. Clients should thus not rely on a given document having the same number between sessions.

    NOTE: IndexReader instances are completely thread safe, meaning multiple threads can call any of its methods, concurrently. If your application requires external synchronization, you should not synchronize on the IndexReader instance; use your own (non-Lucene) objects instead.

    • Method Detail

      • getContext

        public final AtomicReaderContext getContext()
        Description copied from class: IndexReader
        Expert: Returns the root IndexReaderContext for this IndexReader's sub-reader tree.

        Iff this reader is composed of sub readers, i.e. this reader being a composite reader, this method returns a CompositeReaderContext holding the reader's direct children as well as a view of the reader tree's atomic leaf contexts. All sub- IndexReaderContext instances referenced from this readers top-level context are private to this reader and are not shared with another context tree. For example, IndexSearcher uses this API to drive searching by one atomic leaf reader at a time. If this reader is not composed of child readers, this method returns an AtomicReaderContext.

        Note: Any of the sub-CompositeReaderContext instances referenced from this top-level context do not support CompositeReaderContext.leaves(). Only the top-level context maintains the convenience leaf-view for performance reasons.

        Specified by:
        getContext in class IndexReader
      • hasNorms

        @Deprecated
        public final boolean hasNorms​(java.lang.String field)
                               throws java.io.IOException
        Deprecated.
        (4.0) use getFieldInfos() and check FieldInfo.hasNorms() for the field instead.
        Returns true if there are norms stored for this field.
        Throws:
        java.io.IOException
      • fields

        public abstract Fields fields()
                               throws java.io.IOException
        Returns Fields for this reader. This method may return null if the reader has no postings.
        Throws:
        java.io.IOException
      • docFreq

        public final int docFreq​(Term term)
                          throws java.io.IOException
        Description copied from class: IndexReader
        Returns the number of documents containing the term. This method returns 0 if the term or field does not exists. This method does not take into account deleted documents that have not yet been merged away.
        Specified by:
        docFreq in class IndexReader
        Throws:
        java.io.IOException
        See Also:
        TermsEnum.docFreq()
      • totalTermFreq

        public final long totalTermFreq​(Term term)
                                 throws java.io.IOException
        Returns the number of documents containing the term t. This method returns 0 if the term or field does not exists. This method does not take into account deleted documents that have not yet been merged away.
        Specified by:
        totalTermFreq in class IndexReader
        Throws:
        java.io.IOException
      • getSumDocFreq

        public final long getSumDocFreq​(java.lang.String field)
                                 throws java.io.IOException
        Description copied from class: IndexReader
        Returns the sum of TermsEnum.docFreq() for all terms in this field, or -1 if this measure isn't stored by the codec. Note that, just like other term measures, this measure does not take deleted documents into account.
        Specified by:
        getSumDocFreq in class IndexReader
        Throws:
        java.io.IOException
        See Also:
        Terms.getSumDocFreq()
      • getDocCount

        public final int getDocCount​(java.lang.String field)
                              throws java.io.IOException
        Description copied from class: IndexReader
        Returns the number of documents that have at least one term for this field, or -1 if this measure isn't stored by the codec. Note that, just like other term measures, this measure does not take deleted documents into account.
        Specified by:
        getDocCount in class IndexReader
        Throws:
        java.io.IOException
        See Also:
        Terms.getDocCount()
      • getSumTotalTermFreq

        public final long getSumTotalTermFreq​(java.lang.String field)
                                       throws java.io.IOException
        Description copied from class: IndexReader
        Returns the sum of TermsEnum.totalTermFreq() for all terms in this field, or -1 if this measure isn't stored by the codec (or if this fields omits term freq and positions). Note that, just like other term measures, this measure does not take deleted documents into account.
        Specified by:
        getSumTotalTermFreq in class IndexReader
        Throws:
        java.io.IOException
        See Also:
        Terms.getSumTotalTermFreq()
      • terms

        public final Terms terms​(java.lang.String field)
                          throws java.io.IOException
        This may return null if the field does not exist.
        Throws:
        java.io.IOException
      • termDocsEnum

        public final DocsEnum termDocsEnum​(Term term)
                                    throws java.io.IOException
        Returns DocsEnum for the specified term. This will return null if either the field or term does not exist.
        Throws:
        java.io.IOException
        See Also:
        TermsEnum.docs(Bits, DocsEnum)
      • getNumericDocValues

        public abstract NumericDocValues getNumericDocValues​(java.lang.String field)
                                                      throws java.io.IOException
        Returns NumericDocValues for this field, or null if no NumericDocValues were indexed for this field. The returned instance should only be used by a single thread.
        Throws:
        java.io.IOException
      • getBinaryDocValues

        public abstract BinaryDocValues getBinaryDocValues​(java.lang.String field)
                                                    throws java.io.IOException
        Returns BinaryDocValues for this field, or null if no BinaryDocValues were indexed for this field. The returned instance should only be used by a single thread.
        Throws:
        java.io.IOException
      • getSortedDocValues

        public abstract SortedDocValues getSortedDocValues​(java.lang.String field)
                                                    throws java.io.IOException
        Returns SortedDocValues for this field, or null if no SortedDocValues were indexed for this field. The returned instance should only be used by a single thread.
        Throws:
        java.io.IOException
      • getSortedSetDocValues

        public abstract SortedSetDocValues getSortedSetDocValues​(java.lang.String field)
                                                          throws java.io.IOException
        Returns SortedSetDocValues for this field, or null if no SortedSetDocValues were indexed for this field. The returned instance should only be used by a single thread.
        Throws:
        java.io.IOException
      • getDocsWithField

        public abstract Bits getDocsWithField​(java.lang.String field)
                                       throws java.io.IOException
        Returns a Bits at the size of reader.maxDoc(), with turned on bits for each docid that does have a value for this field, or null if no DocValues were indexed for this field. The returned instance should only be used by a single thread
        Throws:
        java.io.IOException
      • getNormValues

        public abstract NumericDocValues getNormValues​(java.lang.String field)
                                                throws java.io.IOException
        Returns NumericDocValues representing norms for this field, or null if no NumericDocValues were indexed. The returned instance should only be used by a single thread.
        Throws:
        java.io.IOException
      • getFieldInfos

        public abstract FieldInfos getFieldInfos()
        Get the FieldInfos describing all fields in this reader.
      • getLiveDocs

        public abstract Bits getLiveDocs()
        Returns the Bits representing live (not deleted) docs. A set bit indicates the doc ID has not been deleted. If this method returns null it means there are no deleted documents (all documents are live). The returned instance has been safely published for use by multiple threads without additional synchronization.