On Thu, Mar 10, 2016 at 12:52:43PM -0500, Russell Bryant wrote: > On Thu, Mar 10, 2016 at 2:11 AM, Ben Pfaff <b...@ovn.org> wrote: > > > Database txn ACID consist trk HA OS C Py format > > ------------- --- ---- ------- --- --- --- --- --- ------ > > ActorDB yes ACID strong NO yes yes yes yes sql > > Aerospike yes ACID strong NO yes yes yes yes db/KV > > Cassandra NO -C-D tunable NO yes yes NO yes table > > Cockroach DB yes ACID strong NO yes yes ? ? sql > > Couchbase NO ???? ???? NO yes NO? yes yes JSON > > CrateIO NO ???? EVNTUAL NO yes yes NO yes sql > > etcd NO ACID strong yes? yes yes yes yes KV > > Gigaspaces XAP yes ACID strong yes yes NO NO NO multi > > HBase NO ACID strong NO yes yes NO yes table > > Hyperdex yes ACID strong NO yes NO yes yes KV > > Hypertable NO ???? ???? NO yes yes NO yes table > > MongoDB NO ACID strong ?? yes yes yes yes JSON > > RAMCloud yes ???? strong NO yes yes NO yes KV > > Redis yes -C?D ???? NO yes yes yes yes KV > > Riak NO ---D EVNTUAL NO yes yes yes yes KV > > Scalaris yes ACI- strong NO yes yes NO yes KV > > ScyllaDB NO -C-D tunable NO yes yes NO yes table > > Voldemort NO ???? EVNTUAL NO yes yes NO yes KV > > Zookeeper yes AC-D strong yes yes yes yes yes KV > > > > OVSDB yes ACID strong yes NO yes yes yes table > > > > I've shared this message with a few people that I work with that have more > experience evaluating these things than I do to gather some feedback. > > Julien Danjou offered the following alternative that I felt was worth > adding to the conversation: > > > Database txn ACID consist trk HA OS C Py format > > ------------- --- ---- ------- --- --- --- --- --- ------ > > PostgreSQL yes ACID strong yes yes yes yes yes sql
I've been a fan of Postgres since I used in the 1990s for a web-based application. It didn't occur to me that it was appropriate here. Julien, thanks so much for joining the discussion. > > So yes, it has everything OVN needs. It can push notifications to > > clients via the NOTIFY¹ command (that you can use in any > > procedure/trigger). For example, you could imagine creating a trigger > > that sends a JSON payload for each new update/insert in the database. > > That's literally 10 lines of PL/SQL. That's good to know. I hadn't figured out how to do this kind of thing with SQL-based systems. > > ¹ http://www.postgresql.org/docs/9.5/static/sql-notify.html > > > > I think that PostgreSQL would be the safer bet in this move, as: > > - building something on top of etcd would seem weak w.r.t your > > schema/table requirements > > - investing in OVSDB (though keep in mind I don't know it :-) would > > probably end up in redoing a job PostgreSQL people already have done > > better than you would ;-) > > > > The only questions that this raises to me are: > > - whether PostgreSQL is too large/complex to deploy for OVN. Seeing the > > list of candidates that were evaluated, I wouldn't think so, but there > > can be a lot of different opinions on that based on different > > perception of PostgreSQL. And since you're targeting a network DB, you > > definitely need a daemon configured and set-up so I'm only partially > > worried here. :) > > I wouldn't think so, but it sounds like I need to study the HA model. OK, I added the entry and this note: - PostgreSQL. Julien Danjou writes: HA can be done, though it requires probably a bit more manual work to be put in place. This can automated in some way, but it's easy to do stream replication with a hot stand by server to recover. Recent versions of PostgreSQL offer tools for that. (Looking at the PostgreSQL 9.4 manual, transaction log shipping with asynchronous transaction log streaming seems appropriate.) Julien continues: It can push notifications to clients via the NOTIFY¹ command (that you can use in any procedure/trigger). For example, you could imagine creating a trigger that sends a JSON payload for each new update/insert in the database. That's literally 10 lines of PL/SQL. > Specific to the OVN+OpenStack use case, I imagine a frequent question would > be, "why do I have to use MariaDB+Galera AND PostgreSQL in the same > environment?!" I suppose OpenStack works with PostgreSQL, too, and it's > just a deployment choice that most people seem to be using MariaDB+Galera. > > Further on that note, I take it MariaDB+Galera is lacking against these > requirements? Or should it be on this list? MariaDB doesn't seem to have NOTIFY and related functionality, based on documentation and web searches. It does tick all the other boxes. I added: Database txn ACID consist trk HA OS C Py format ------------- --- ---- ------- --- --- --- --- --- ------ MariaDB yes ACID strong NO yes yes yes yes sql _______________________________________________ dev mailing list dev@openvswitch.org http://openvswitch.org/mailman/listinfo/dev
