Class Lucene40SegmentInfoFormat

Lucene 4.0 Segment info format.

Files:

• .si: Header, SegVersion, SegSize, IsCompoundFile, Diagnostics, Attributes, Files

• Header --> CodecHeader (WriteHeader(DataOutput, String, Int32))
• SegSize --> Int32 (WriteInt32(Int32))
• SegVersion --> String (WriteString(String))
• Files --> ISet<String> ()
• Diagnostics, Attributes --> IDictionary<String,String> ()
• IsCompoundFile --> Int8 (WriteByte(Byte))

• SegVersion is the code version that created the segment.
• SegSize is the number of documents contained in the segment index.
• IsCompoundFile records whether the segment is written as a compound file or not. If this is -1, the segment is not a compound file. If it is 1, the segment is a compound file.
• Checksum contains the CRC32 checksum of all bytes in the segments_N file up until the checksum. This is used to verify integrity of the file on opening the index.
• The Diagnostics Map is privately written by IndexWriter, as a debugging aid, for each segment it creates. It includes metadata like the current Lucene version, OS, .NET/Java version, why the segment was created (merge, flush, addIndexes), etc.
• Attributes: a key-value map of codec-private attributes.
• Files is a list of files referred to by this segment.