What is a database file system?

I have a very little idea about what database file system is.

Can somebody out here explain to me what actually a database file system is, and what its applications are? How is it different from a conventional file s开发者_StackOverflow社区ystem?

How I can build it?

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Typical file systems (*nix, ms-dos, etc) organize files hierarchically. For example,

c:\ represents the top of a hierarchy c:\foo is the next level in the hierarchy c:\foo\bar is a sub-node of \foo etc..

Each file exists in one and only one location in this hierarchy.

By contrast, a database file system organizes files by metadata attributes. For example, topic, type, author, etc.. Rather than existing in one particular place in a hierarchy, the file exists in multiple "places" depending on its attributes.

The last question you ask is unanswerable.

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Found some good links

• DBFS (This one is really good)
• Towards A Single Folder Filesystem

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It's a file system where files have significant amounts of metadata. For example, the iTunes library might count as a database file system; not only do you have files on disk and know where they are, but you have tags (genres) and other metadata like author (artist).

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It's a file system that stores files as blobs in a database, rather than in a hierarchy of directories. Imagine a web-site with no "directory-like" hierarchy in the URL - just loads of tags and categories and a big "search" field - something like that, only on your hard-drive.

Pros & cons? Ask yourself, how many database filesystems have I ever seen? Do you need to ask more?