Path: utzoo!utstat!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!newstop!sun!amdcad!dgcad!gary
From: gary@dgcad.sv.dg.com (Gary Bridgewater)
Newsgroups: news.software.b
Subject: Re: Bnews and dbz
Message-ID: <656844007.10844@proa.sv.dg.com>
Date: 25 Oct 90 08:40:07 GMT
References: <27155@mimsy.umd.edu>
Organization: Data General SDD, Sunnyvale, CA
Lines: 31

In article <27155@mimsy.umd.edu> pete@mimsy.umd.edu (Pete Cottrell) writes:
>
>	I'm sure this has been discussed before, but I wasn't interested
>then so didn't retain it. The question is: can I use the dbz routines
>to make my Bnews expire run faster? Does it require a certain patch level?
>Is it is easy or hard to do? Any horror stories?

Yes you can.  I run it on patch level 17.  It does go much faster - especially
if you have enough menory to use INCORE for expire (memory use ~= size
of history file + code).   If you use INCORE then you must wade through
expire.c and find the places where it exits and issue a dbmclose to flush
the dbm data back out.
You need to understand how the INDEX_SIZE value works - if it is too small
the hash table overflows and duplicates occur a lot (this is the *horror* part).
It is a function of your history file size, e.g. I use 3000017 for a 40 day
history (about 12 Mbytes). (Actually it is a function of the number of entries
in the history file but who has time to count them).  Your history.pag file
will appear to be 4x this (4 bytes per entry) but won't really take that
much space if your system does sparse file allocation.
There is no point in building inews with the INCORE value set so I keep
a libdbzi.a and a libdbz.a.  I don't think there is much point in using
INCORE without sufficient memory to keep it all there either although
paging may be cheaper than doing the i/o in the program (WAG).
The preceeding is based on the dbz before the one recently announced for
C-News which was advertised to handle INCORE on the fly among other features.
P.s. If you run nntp it must be built with the same dbz.
And, of course, when you switch - and anytime you change INDEX_SIZE you must
rebuild (inews -r) the history database.
-- 
Gary Bridgewater, Data General Corporation, Sunnyvale California
gary@sv.dg.com or {amdahl,aeras,amdcad}!dgcad!gary
C++ - it's the right thing to do.