Re: using reiserfs as a DB

[Oleg Drokin <green@namesys.com>]

Hello!

On Sun, Apr 21, 2002 at 03:53:28PM -0500, Phil Howard wrote:
> Given the balanced tree directory structure of reiserfs, it seems it
> could be usable as a DB in place of a DB library (such as Berkeley DB).
> Has anyone done any timing/benchmarks of reiserfs used as a replacement
> for a DB library, as compared to one such as Berkeley DB?  There would
> be an advantage to using conventional file tools to access the data
> instead of having to code some up for a DB library.  The issue would
> certainly involve the open/read/close timings for reiserfs for each
> piece of data accessed.  The uses for which I have an interest in doing
> this would most be small data, usually less than 128 bytes, and almost
> always less than 512 bytes.  For example, one use involves indexing a
> lot of (100s to maybe even 1000000) URLs under special short keywords.

I do not have any numbers, but take in account that while DB database
generally have to updata atime/mtime/ctime on only 3 files (or even 2),
in case of a filesystem each file accessed will change atime and/or mtime/ctime.

(you can turn off atime updates of course). Also directory lookups ain't going
to be free either.
I've not heard of a test like you are describing, so feel free to implement
one that will suit all your needs.

But I remember that squid people decided lookup/open/close operations are
too expensive for them and raw reiserfs access was born, where you was able
directly access filesystems objects by the keys. 

Bye,
    Oleg