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Article #2767Re: parttionned database
From: Henry J. Cobb
Date: Fri, 22 Apr 1994 16:43
Date: Fri, 22 Apr 1994 16:43
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2013 bytes
Sorry, but you're trying to beat the system programmers at their own job and it's not going to work. The overhead the system has in vnodes is more than offset by efficiencies in caching and device management. The raw disk system will be slower than Ace is now with a single reader, and much slower with multiple readers (as they page out each other's read buffers, because the pages have been dirtied with the data read from disk). There are certain gains you could make in writes, but mostly the database just reads. It would be much better to do Read In Place(RIP?), where the database file is mmap()ed in, object references are given as offsets from the base of the file and the data is referenced in place. The system manages your buffer, and it's exactly as big as it can afford, plus all of the readers share the same buffer and normally don't need to duplicate the data in the database into their private pools, as they can refer to it directly. The effect is that zero copies in memory are made, as you're drinking from the system's own buffers and it can simply drop your pages at will, because you haven't changed what it's read. -- Henry J. Cobb hcobb@fly2.berkeley.edu, SFB Tyrant-for-life "Battleships cannot be used as escorts" -SVC (quite a shock for the crew of the Iowa, I'd wager)
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X-Google-Language: ENGLISH,ASCII-7-bit X-Google-Thread: f6d40,d3f400bd2ff90c48 X-Google-Attributes: gidf6d40,public X-Google-ArrivalTime: 1994-04-22 09:43:40 PST Path: arc1-ca.pugleaf.net!gmd.de!nntp.gmd.de!xlink.net!howland.reston.ans.net!agate!agate!hcobb From: hcobb@fly2.berkeley.edu (Henry J. Cobb) Newsgroups: bionet.software.acedb Subject: Re: parttionned database Date: 22 Apr 1994 16:43:40 GMT Organization: University of California, Berkeley Lines: 30 Message-ID: <HCOBB.94Apr22094340@fly2.berkeley.edu> References: <2p0gi6$898@mserv1.dl.ac.uk> NNTP-Posting-Host: fly2.berkeley.edu In-reply-to: mieg@kaa.crbm.cnrs-mop.fr's message of 19 Apr 1994 12:50:30 +0100