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
