Streaming File System

摘要

An indexing system and method for a filesystem, such as a database using the POSIX application programming interface, uses two fractal tree indices, a metadata index mapping the full pathname of files to file metadata, preferably data such as returned with a struct stat call, and a data index mapping pathname and block number to a datablock of a predetermined size, optionally a fixed size. The data index has keys ordered lexicographically, and the system and method allows for modifying existing keys, and creating new keys if there is no existing key, for writes smaller than the predetermined block size and for unaligned writes. The invention provides at least about an order of magnitude improvement in microdata operations (such as creating and scanning files smaller than a predetermined size, such as 512-byte files), and has write times comparable with existing file systems.

主权项

1. An index structure for a filesystem, comprising:
a metadata index in the form of a fractal tree comprising a mapping of the full pathname of a file in the filesystem to the metadata of the file; a data index in the form of a fractal tree comprising a mapping of the pathname and block number of a file in the filesystem to a data block of a predetermined size, said data index having keys, each key specifying a pathname and block number, said keys ordered lexicographically; and an application programming interface for said filesystem including a dictionary and a specification therefor, and a message in the dictionary specification, that, in the case that a filesystem command requires writing fewer bytes than said predetermined size, and in the case that a filesystem command comprises executing an unaligned disk write, modifies the key in the data index for such written data and, when such key is absent, creates the key.