Class Lucene90CompoundFormat


public final class Lucene90CompoundFormat extends CompoundFormat
Lucene 9.0 compound file format


  • .cfs: An optional "virtual" file consisting of all the other index files for systems that frequently run out of file handles.
  • .cfe: The "virtual" compound file's entry table holding all entries in the corresponding .cfs file.


  • Compound (.cfs) --> Header, FileData FileCount, Footer
  • Compound Entry Table (.cfe) --> Header, FileCount, <FileName, DataOffset, DataLength> FileCount
  • Header --> IndexHeader
  • FileCount --> VInt
  • DataOffset,DataLength,Checksum --> UInt64
  • FileName --> String
  • FileData --> raw file data
  • Footer --> CodecFooter


  • FileCount indicates how many files are contained in this compound file. The entry table that follows has that many entries.
  • Each directory entry contains a long pointer to the start of this file's data section, the files length, and a String with that file's name. The start of file's data section is aligned to 8 bytes to not introduce additional unaligned accesses with mmap.