Path: utzoo!attcan!uunet!virtech!cpcahil
From: cpcahil@virtech.uucp (Conor P. Cahill)
Newsgroups: comp.unix.questions
Subject: Re: unix file structure (or lack of same)
Keywords: unix, file, database
Message-ID: <1990Nov05.113344.21474@virtech.uucp>
Date: 5 Nov 90 11:33:44 GMT
References: <125379@linus.mitre.org>
Reply-To: cpcahil@virtech.UUCP (Conor P. Cahill)
Organization: Virtual Technologies Inc., Sterling VA
Lines: 28

In article <125379@linus.mitre.org> duncant@mbunix.mitre.org (Thomson) writes:
>I understand that, on unix, the file system is designed so that a file always
>looks like a sequence of bytes, with no record structure at all.

No *system imposed* record structure.

>If so, how does one implement an efficient database manager on unix in
>a standard, portable, way?  To be efficient, a database manager needs to

By having an application imposed record structure.

>have random access into files on a record-oriented basis.  It seems to me
>that fseek() wouldn't do the job.  

Most UNIX DBMSs will use read/write/lseek as opposed to the stdio functions
to ensure that the stdio buffering does not get in the way.

>provide a record-oriented view of files, then any database implementation 
>would have to go below unix, and access the mass storage devices directly.
>Is this right?

Nope.  It would only have to impose its own record structure on the file.


-- 
Conor P. Cahill            (703)430-9247        Virtual Technologies, Inc.,
uunet!virtech!cpcahil                           46030 Manekin Plaza, Suite 160
                                                Sterling, VA 22170