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Date:      Tue, 03 Mar 1998 12:31:22 -0800 (PST)
From:      Simon Shapiro <shimon@simon-shapiro.org>
To:        stephen farrell <stephen@farrell.org>
Cc:        freebsd hackers <hackers@FreeBSD.ORG>
Subject:   RE: hook database into filesystem like BeOS?
Message-ID:  <XFMail.980303123122.shimon@simon-shapiro.org>
In-Reply-To: <87pvk3sj07.fsf@phaedrus.uchicago.edu>

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On 03-Mar-98 stephen farrell wrote:
 
...

> so my question is: 1. anyone thinking about this?  2. how difficult do
> you think it would be to get started playing with this--adding hooks
> to the vfs layer to maintain the state in a rdbms (mysql, postgres,
> etc)?  3. do you think it might be possible that such a system could
> be, in principal, integrated with the c library so that applications
> (e.g., find, file managers) would use it while calling the existing
> api (analagous to nis vs. passwd file... perhaps a /etc config file
> telling it whether it should use database, if so what kind, if so
> which hostname is the database on, etc)?

Yes, I am.  Although nice and highly optimized for their own declared
purpose (video streams, if I remember), this structure is not fit for most
RDBMS storage managers.  Database engines tend to view the disk as an array
of blocks and no more.  In Postgres, for example (I would have commented on
Oracle OSD but cannot), you simply cannot do anything to the disk other
than read a block, and write a block. (Well, there are few others). 
Locking cannot and should not be associated with disk blocks, as in an
RDBMS you want to be able to lock abstract objects that may map to vlocks,
may not map to blocks, map to multiple blocks, etc.

If you examine the lock manager in Postgres, you will see what I mean. 
Locking ``one'' object can translate to several hundred lock operations.
Ugly indeed.

Since you opened this can of worms, I'll add that there is a loose group of
us which contemplates the merging of RDBMS storage management and a Unix
O/S.  This is an interesting subject, and FreeBSD is actually a good O/S
for this type of work.


----------


Sincerely Yours, 

Simon Shapiro
Shimon@Simon-Shapiro.ORG                      Voice:   503.799.2313

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