From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lucio De Re To: 9fans@cse.psu.edu Subject: Re: [9fans] silly replica question (repeated m msgs won't go away) Message-ID: <20040210192404.T17981@cackle.proxima.alt.za> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: ; from Charles Forsyth on Tue, Feb 10, 2004 at 04:10:20PM +0000 Date: Tue, 10 Feb 2004 19:24:05 +0200 Topicbox-Message-UUID: dd020a14-eacc-11e9-9e20-41e7f4b1d025 On Tue, Feb 10, 2004 at 04:10:20PM +0000, Charles Forsyth wrote: > > i don't think i'd describe what replica attempts as `heuristic'. > there's a little graph of possibilities and it either chooses the safe > path or requests guidance. > I really hope I don't sound confrontational, there's much I don't know and can only guess at, but there's definitely more than a trivial amount of slipperiness about replica that makes it unsuitable for the type of replication that Microsoft used (or used to use) to propagate changes to the users database between the PDC and BDCs (if you don't know the acronym, you're missing nothing) or what Lotus Notes uses (this is NetNews in disguise or is it on steroids?) or, for that matter, the OpenLDAP replicator. > an SHA1 hash would be helpful; by using mtime+length it can moan about > insignificant changes but then again, with some things it's possible > the mtime matters, and perhaps it should moan. > I think there's a philosophy behind replica that suggests humans are involved therefore there's scope for some fuzzy logic. I'm not even arguing the merits thereof, it's a perfectly good approach. What I prefer, however, is the solidity of the dump and a tool to extract the updates list in a format that makes it possible to revert them and/or apply them elsewhere. I'd better be careful, however, I'm beginning to recognise signs that my attraction for CVS is coming through. > having mentioned SHA1: there might be an interesting variant that uses > venti scores. I won't try to follow your thinking there, it's way beyond my processing powers :-) ++L