On 20 May 2014 20:53, Julien Danjou <[email protected]> wrote: > On Mon, May 19 2014, Jay Pipes wrote: > >> I think at that point I mentioned that there were a number of places that >> were using the SELECT ... FOR UPDATE construct in Nova (in SQLAlchemy, it's >> the with_lockmode('update') modification of the query object). Peter >> promptly said that was a problem. MySQL Galera does not support SELECT ... >> FOR UPDATE, since it has no concept of cross-node locking of records and >> results are non-deterministic. > > So you send a command that's not supported and the whole software > deadlocks? Is there a bug number about that or something? I cannot > understand how this can be possible and considered as something normal > (that's the feeling I have reading your mail, I may be wrong).
No, Galera keeps right on running, and signals a transaction rollback to the client. > 5) Stop leveling down our development, and rely and leverage a powerful > RDBMS that provides interesting feature, such as PostgreSQL. > > Sorry, had to say it, but it's pissing me off to see the low quality of > the work that is done around SQL in OpenStack. I'm a huge PostgreSQL fan, but last I heard PostgreSQL-XC was still fairly raw (and PostgreSQL replication + failover is a PITA to operate, so please don't suggest that as equivalent :)). I do have huge sympathy for the idea of picking a single specific implementation of common layers and then deriving advantage from, but thats not how our community has grown so far: - we support many RDBMS - we support many MQs - we support many dogpile cache backends If we're going to change this we need to have a fairly broad discussion about the impact - the pros *and cons*. There's a certain amount of hybrid vigour we get from supporting multiple backends - we can scale in ways that a single backend might not; we can deploy in environments that have hard corporate policies about 'the one true $X is $Y'. -Rob -- Robert Collins <[email protected]> Distinguished Technologist HP Converged Cloud _______________________________________________ OpenStack-dev mailing list [email protected] http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
