regarding this " The fault is that almost nobody does it right: they neglect to keep an 'unaltered central copy' and think they can cross-apply journals each time two databases talk to one-another. That does not work for various reasons."
Would a central repository of journals that can be applied to local repositories be sufficient? I suppose I assume that running the same program on N workstations with the same set of journals should produce N identical results. On Wed, Oct 7, 2009 at 12:16 PM, Simon Slavin <slav...@hearsay.demon.co.uk>wrote: > > On 7 Oct 2009, at 1:47pm, Jean-Denis Muys wrote: > > > On 10/7/09 11:50 , "Simon Slavin" <slav...@hearsay.demon.co.uk> wrote: > > > >> Try really really hard just to have all sites access your MySQL > >> database remotely. > > > > Unfortunately this approach is not possible in the short term. The > > client > > applications are legacy applications, porting them to that scheme is > > a major > > undertaking. [snip] > > I completely understand. The recommendation is valuable in the > general case, but useless in yours. Still, that's why they pay you > the big bucks: to write the complicated program. > > >> Keep a journal. Keep an unaltered central copy of the data. As each > >> site contacts the central site, play that sites journal back against > >> the unaltered central copy. The post-journal central copy of the > >> database becomes the new copy for distribution. > > > > Interesting idea, that makes a lot of sense in the "offline" scenario. > > Standard solution to the synchronisation problem. The fault is that > almost nobody does it right: they neglect to keep an 'unaltered > central copy' and think they can cross-apply journals each time two > databases talk to one-another. That does not work for various reasons. > > The synchronisation service built into Mac OS X (e.g. synchronising > with online services or an iPhone/iPod) implements it in the correct > manner. It takes extra data space and fussy programming but it does > at least work right ! > > > [snip] In any case, any book reference on this topic? > > Since I joined this list and noticed repeated questions on the subject > I have been trying hard to find any book with anything significant to > say on the issue. I failed: everything I found was lacking in some > way. Some were flat-out wrong. I work at a university and I think > I'm going to ask the Computing people to find me someone who knows > this stuff. I'm just paid to do it in real life, not read or write > books about it. If I find something good I'll read it and post here > about it. > > Simon. > _______________________________________________ > sqlite-users mailing list > sqlite-users@sqlite.org > http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users > -- VerifEye Technologies Inc. 905-948-0015x245 7100 Warden Ave, Unit 3 Markham ON, L3R 8B5 Canada _______________________________________________ sqlite-users mailing list sqlite-users@sqlite.org http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
