The file extension .metadata_never_index is a command file used for forestalling metadata indexing of designated files, folders or partitions on the hard drive. Metadata consists of resource pointers for data, which documents origin, attributes and other file characteristics. At times, the metadata indexing is redundant and only slows down memory and fills up disk space unnecessarily.
Used by the Apple Macintosh operating system as a settings file, the .metadata_never_index file extension is one of the only ways to prevent certain indexing programs like Apple Spotlight from automatically indexing the metadata. Apple Spotlight is a program for searching, indexing and launching data and applications in the Apple Macintosh system. It has advanced searching options using names and metadata. It allows for using sophisticated questions for searches. It also launches applications faster and provides for a Web history search.