Package org.apache.lucene.index

Class SegmentReader

  • All Implemented Interfaces:
    Closeable, AutoCloseable
    public final class SegmentReader
extends CodecReader
    IndexReader implementation over a single segment.

    Instances pointing to the same segment (but with different deletes, etc) may share the same core data.

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

    • Method Detail

      • getLiveDocs

        public Bits getLiveDocs()
        Description copied from class: LeafReader
        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.

        Specified by:
        getLiveDocs in class LeafReader

      • getFieldInfos

        public FieldInfos getFieldInfos()
        Description copied from class: LeafReader
        Get the FieldInfos describing all fields in this reader.

        Note: Implementations should cache the FieldInfos instance returned by this method such that subsequent calls to this method return the same instance.

        Specified by:
        getFieldInfos in class LeafReader

      • numDocs

        public int numDocs()
        Description copied from class: IndexReader
        Returns the number of documents in this index.

        NOTE: This operation may run in O(maxDoc). Implementations that can't return this number in constant-time should cache it.

        Specified by:
        numDocs in class IndexReader

      • maxDoc

        public int maxDoc()
        Description copied from class: IndexReader
        Returns one greater than the largest possible document number. This may be used to, e.g., determine how big to allocate an array which will have an element for every document number in an index.
        Specified by:
        maxDoc in class IndexReader

      • getTermVectors

        public final Fields getTermVectors​(int docID)
                            throws IOException
        Description copied from class: IndexReader
        Retrieve term vectors for this document, or null if term vectors were not indexed. The returned Fields instance acts like a single-document inverted index (the docID will be 0).
        Overrides:
        getTermVectors in class CodecReader
        Throws:
        IOException

      • getSegmentName

        public String getSegmentName()
        Return the name of the segment this reader is reading.

      • getSegmentInfo

        public SegmentCommitInfo getSegmentInfo()
        Return the SegmentInfoPerCommit of the segment this reader is reading.

      • directory

        public Directory directory()
        Returns the directory this index resides in.

      • getReaderCacheHelper

        public IndexReader.CacheHelper getReaderCacheHelper()
        Description copied from class: IndexReader
        Optional method: Return a IndexReader.CacheHelper that can be used to cache based on the content of this reader. Two readers that have different data or different sets of deleted documents will be considered different.

        A return value of null indicates that this reader is not suited for caching, which is typically the case for short-lived wrappers that alter the content of the wrapped reader.

        Specified by:
        getReaderCacheHelper in class IndexReader

      • getCoreCacheHelper

        public IndexReader.CacheHelper getCoreCacheHelper()
        Description copied from class: LeafReader
        Optional method: Return a IndexReader.CacheHelper that can be used to cache based on the content of this leaf regardless of deletions. Two readers that have the same data but different sets of deleted documents or doc values updates may be considered equal. Consider using IndexReader.getReaderCacheHelper() if you need deletions or dv updates to be taken into account.

        A return value of null indicates that this reader is not suited for caching, which is typically the case for short-lived wrappers that alter the content of the wrapped leaf reader.

        Specified by:
        getCoreCacheHelper in class LeafReader

      • getHardLiveDocs

        public Bits getHardLiveDocs()
        Returns the live docs that are not hard-deleted. This is an expert API to be used with soft-deletes to filter out document that hard deleted for instance due to aborted documents or to distinguish soft and hard deleted documents ie. a rolled back tombstone.
        WARNING: This API is experimental and might change in incompatible ways in the next release.

      • checkIntegrity

        public void checkIntegrity()
                    throws IOException
        Description copied from class: LeafReader
        Checks consistency of this reader.

        Note that this may be costly in terms of I/O, e.g. may involve computing a checksum value against large data files.

        Overrides:
        checkIntegrity in class CodecReader
        Throws:
        IOException