On Sun, Aug 24, 2003 at 02:02:06PM -0400, Eric Frazier wrote: > Sounds very biblical. :)
Yeah, I have it etched on a pair of stone tablets around here somewhere... :-) > Wouldn't there be a way to do this with two copies of mysql that > share a common data dir? Maybe. But that's not what he's asking about. It's a bit tricky to do correctly, doesn't work in all cases, and is often more trouble that it's worth. > I don't know if you could do that with InnoDB, but I wonder if you > could with myisam? You can do it with MyISAM, but not InnoDB or BDB. > At least if you had a system where the two sets of tables came from > a different master, and there was no overlap, or if the slave was > just functioning as a backup, maybe it would be possible and not > lead to too much horror? Wel, that's the trick. What I've found is that in order to understand the possible "horrors", you end up having to bump into numerous problems along the way. In the end you realize that it probably would have been better to look at the problem a bit different, such as "chaining" together the two masters, or running completely separate instances of MySQL on the slave machine rather than trying to mix and match the data. I guess that what it comes down to is this. MySQL's replication was designed for relatively simple master/slave setups with 1 master and 1 or more slaves. By taking advantage of the simplicity of MyISAM tables and really knowing how replication works, MySQL does locking, and so on... you can often use it in ways that were not intended. The problem with doing so is that you *are* using it ways that were not intended. That may cause strange problems down the line. Now I've done more than my fair share of abusing MySQL in strange configurations. Some have worked quite well and others have not. I'm not saying "don't do this" but it's not something to simply dive into either. Jeremy -- Jeremy D. Zawodny | Perl, Web, MySQL, Linux Magazine, Yahoo! <[EMAIL PROTECTED]> | http://jeremy.zawodny.com/ MySQL 4.0.13: up 23 days, processed 1,073,046,344 queries (536/sec. avg) -- MySQL General Mailing List For list archives: http://lists.mysql.com/mysql To unsubscribe: http://lists.mysql.com/[EMAIL PROTECTED]
