org.apache.lucene.codecs.lucene90.Lucene90CompoundFormat

Lucene 9.0 compound file format

Files:

• .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.

Description:

• 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

Notes:

• 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 64 bytes to not introduce additional unaligned accesses with mmap.