On Tue, Sep 26, 2006 at 08:21:44AM +0200, Bo Lorentsen wrote: > seems like they have some kind of statement queue (no trigger setup) and > a transfer protocol all integrated in the server, and that makes it > "simpel". There is no understanding regarding transactions, as far as I > have seen. Note that, the last time I looked at it, there was no interlock to ensure that your statement queue (which is basically just a log of statements as executed on the "master") was not accidentally blown away by your cleanup process before your target replicas were up to date. This might have improved recently, but when I looked at it MySQL's async replication was high on the "ease of use" and low on the "works in sticky situations". As I say, they may have fixed it; but I advise people to look very carefully at how it works before deciding it is adequate. The important thing to remember about database replicas is that you're _already_ planning for the small percentage of cases where things break. Therefore, an 80/20 solution is not good enough: the thing has to work when most things have broken, or it's no use to you. > That makes sense ... then the only thing to worry about is where these > "baches" are written. On the same disk as the master database or on the > client side, or will it be advisable to use a NFS mount between these to > machines to balance the disk writing ? No. I suggest you have a look at the docs, and take these questions to the (again functioning) Slony list, where people can advise about that. The short answer is that the things to write are stored in the origin for the table (don't think of it as a database replica, because you can have different tables originating in different nodes). You can _also_ write sets out to disk, if you like. Someone (my colleagues, in fact) appear to have a nasty bug in that functionality that they can't nail down; nobody else has reproduced it. A -- Andrew Sullivan | ajs@xxxxxxxxxxxxxxx Unfortunately reformatting the Internet is a little more painful than reformatting your hard drive when it gets out of whack. --Scott Morris
