On Tue, 23 Mar 2010 13:03:34 +0200, Henrik Ingo <henrik.i...@avoinelama.fi> wrote: > On Tue, Mar 23, 2010 at 10:40 AM, <seppo.jaak...@codership.com> wrote: >>> At least the application of replicated transactions certainly should >>> not be part of each storage engine. From the engine point of view, >>> applying a set of replicated transactions should be "just another >>> transaction". For the engine it should not matter if a transaction >>> comes from the application, mysqldump, or a redundancy service. (There >>> may be small details: when the application does a transaction, we need >>> a new global txn id, but when applying a replicated transaction, the >>> id is already there.) >>> >> >> yes, but no. .e.g. Galera replication has this strange need to use >> prioritized transactions for applying. DBMS should have the >> responsibility >> to provide high priority sessions for replication appliers. > > So Galera only works with the engines you have hacked to support it? > (Which I fear is InnoDB only?) > > Like I said, we can still list a set of details the engine needs to > support, but in general of course we should be able to replicate from > any table/engine into any table/engine without having "replication > support" in each engine separately. > > But on the face of it, your requirement does make sense for > synchronous replication. (And for the traditional asynchronous > replication, users generally want the lag to be a small as possible > too.) > > henrik
High-priority here means that this transaction can abort any other that stands in its way. Actually this is a requirement only to have Galera working in multi-master mode. And it does not look like an engine requirement, rather a lock manager feature (rather useful though - on slave it guarantees that transactions received from master will never deadlock with local transactions). So I think the server may or may not provide such a feature, it should not really affect the redundancy API. I'd say that it belongs to the integration layer. Alex _______________________________________________ Mailing list: https://launchpad.net/~maria-developers Post to : maria-developers@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-developers More help : https://help.launchpad.net/ListHelp
