Subject: Re: Question regarding to store file system metadata in database
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Xin Zhao <uszhaoxin@gmail.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org
In-Reply-To: <4ae3c140603182048k55d06d87ufc0b9f0548574090@mail.gmail.com>
References: <4ae3c140603182048k55d06d87ufc0b9f0548574090@mail.gmail.com>
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Date: Sun, 19 Mar 2006 23:06:25 +0000
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On Sad, 2006-03-18 at 23:48 -0500, Xin Zhao wrote:
> database system. I ran a test on a mysql database: I inserted about
> 1.2 million such kind of records into an initially empty mysql
> database. Average insertion rate is about 300 entries per second,

Thats extremely slow for a file system. 

> Then I am a little curious why only few people use database to store
> file system metadata, although I know WinFS plans to use database to
> manage metadata. 

The one well known example of a database as file system (or was well
known) was the Pick OS (now defunct although the database system lives
on). They did manage to build an OS which had a database as a file
system.

The thing is a database and a file system are the same thing anyway.
You'll find the same structures like B trees used in some for example.
They are just optimised for different kinds of queries. If you want to
know whether a db as fs works , build a prototype and see - you've
already taken the first step and with FUSE you can prototype the rest in
user space.

Alan

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