Path: utzoo!utgpu!jarvis.csri.toronto.edu!cs.utexas.edu!uunet!dev!dgis!jkrueger
From: jkrueger@dgis.dtic.dla.mil (Jon)
Newsgroups: comp.arch
Subject: Re: the Multics from the black lagoon :-)
Message-ID: <756@dgis.dtic.dla.mil>
Date: 12 Feb 90 05:04:31 GMT
References: <8859@portia.Stanford.EDU> <20571@watdragon.waterloo.edu> <PCG.90Feb11213549@rupert.cs.aber.ac.uk>
Organization: Defense Technical Information Center (DTIC), Alexandria VA
Lines: 31

pcg@rupert.cs.aber.ac.uk (Piercarlo Grandi) writes:

>(use Multics RDMS, and then read what Stonebraker
>has to say about how suitable is Unix for Ingres).

A reading from the book of Stonebraker, The INGRES Papers: Anatomy of a
Relational Database System, Chapter 8, Operating System Support for
Database Management, (originally CACM 24:7, July 1981):

	"A DBMS would prefer a small efficient operating system
	 with only desired services provided ... most general
	 purpose operating systems provide all things to all
	 people at much higher overhead.  Hopefully, future
	 operating systems will be able to provide both sets
	 of services in one environment."

The paper is a nice overview of alternatives which lead to this
conclusion.  One section deals with how DBMS might use mapping files
into address spaces.  One tradeoff examined is the overhead of page
tables, the time cost of faulting the tables or the space cost of
keeping them resident.  The alternate of mapping "chunks" of the file
into the space (as discussed here) has its own tradeoff: increased
complexity and the overhead of each mapping operation.  Mapping
each chunk into a separate space isn't mentioned, or using sparse
spaces.

-- Jon
-- 
Jonathan Krueger    jkrueger@dtic.dla.mil   uunet!dgis!jkrueger
The Philip Morris Companies, Inc: without question the strongest
and best argument for an anti-flag-waving amendment.