Hello, ---- Original Message ---- From: Aaron Stone <dbmail-dev@dbmail.org> To: dbmail-dev@dbmail.org Subject: Re: [Dbmail-dev] RE: unique_id discussion/problem Sent: Thu, 12 Jun 2003 07:21:42 -0700 (PDT)
> In fact, I would highly recommend that a database is used. I envision a > table that has a row for each server in the cluster and a "uuid prefix" or > something to the like. Synchronization information might also be stored in > this table, such as the IP address of each server as it links up with a > row in the database and the timestamp of when it last attached. > > Naturally this table will have to be replicated, and so it should not have > an auto_increment column, but something else more unique. Hostnames or IP > addresses are an obvious answer, if not a good one ;-) I don't think ip addresses would be unique enough - some cluster implimentations have multiple machines with the same address (eg. via load-balancing hardware switches). Nor hostname (eg. we have multiple machines for mail.kci.net - while they do have unique hostnames also, there's no reason they would necessarily have to). The mac addr seems like the best almost-always-unique identifier that's readily available cross-platform. > I'm not sure what the "non-volatile" storage is needed for in your > proposal beyond what I see as a unique prefix for each dbmail in the > cluster as it writes to a replicated database server... Saved state info is basically for rollbacks in time (eg. machine reboots) and to make multiple uuids generated w/in the same clock tick be unique (because they're based largely upon time). > Aaron > -- End Original Message -- -- Jesse Norell jesse (at) kci.net
