Re: virtualizing local users

From: Ralf Hildebrandt (no email)
Date: Tue Jul 02 2002 - 05:26:49 EDT


On Tue, Jul 02, 2002 at 04:15:48AM -0500, Phil Howard wrote:

> Accessing one large map is faster than accessing one smaller map? If
> that's true, then I'll add a million dummy entries to make it faster.

I was not talking about adding garbage to the map.

> Actually, the performance of accessing the map isn't the reason I want
> to split by domain. It's a maintenance issue. Suppose there are 1000
> domains with an average of 500 users each. The program that generates
> the maps when there is a change would be exposed to 1000 times more
> updates, and have 1000 times more work to do, each time a change is
> made. That's O(N^2) for N = number of domains. Then there is the
> issue of maintenance permission per domain. I need to leave open the
> possibility that different domains will be managed by different user
> access permissions. That might become part of the design.

Valid point. But why not use a map instead that does NOT require
rebuilding (like LDAP!)

Looking up something in one btree:
O(n) = ln(n) (well, sort of)

Looking up something in x btrees of size (n/x):

O(n) = x*ln(n/x)
which is bigger than ln(n)

-- 
Ralf Hildebrandt (Im Auftrag des Referat V A)   
Charite Campus Virchow-Klinikum                 Tel.  +49 (0)30-450 570-155
Referat V A - Kommunikationsnetze -             Fax.  +49 (0)30-450 570-916
"Real programmers can write assembly code in any language." 
                                              -- Larry Wall
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