public FileKeyIndex(AbstractBufferedReader reader, Guid? guid, bool withCommitUlong, bool modern)
{
_guid = guid;
_generation = reader.ReadVInt64();
_trLogFileId = reader.ReadVUInt32();
_trLogOffset = reader.ReadVUInt32();
_keyValueCount = (long)reader.ReadVUInt64();
_commitUlong = withCommitUlong ? reader.ReadVUInt64() : 0;
_compressionType = modern ? (KeyIndexCompression)reader.ReadUInt8() : KeyIndexCompression.Old;
}