SymmetricDS looks like the best alternative so far for the application I am working on. The application they developed for is a close match to the kind of data sync I need. Thanks for the link to the article. I will run a test implementation.
On Nov 11, 11:56 pm, shem p <[email protected]> wrote: > Maybe any of this would > help:http://www.haroonidrees.com/2009/04/open-sour.html > > On Nov 12, 2:07 pm, ron_m <[email protected]> wrote: > > > Thanks for the pointers from both of you, I appreciate that. It would > > be best to have multiple master but that will be very difficult. > > Bucardo has multiple master but only for 2 masters once you get into > > the docs for it. The MySQL scheme I mentioned used primary key > > skipping on autonumbers so if the pool of replicas could reach 10 the > > autonumber increment was set to 10 then each machine got an offset to > > start with. It looks like PostgreSQL can do this as well with the > > sequences but appears to be a DDL setting and not a DB server config > > setting. I am new to PostgreSQL so I may not have found that aspect > > yet. By being careful with the app design I think I can get it down to > > one master which is more manageable and avoid key conflicts. > > > Ron > > > On Nov 11, 1:00 pm, Michele Comitini <[email protected]> > > wrote: > > > > There are some good news for postgresql 9.0: > > > >http://www.postgresql.org/docs/9.0/interactive/warm-standby.html > > > > some of those features above are possible on 8.4 with some difficult > > > configuration tricks, see wiki.postgresql.org. > > > > mic > > > > 2010/11/11 mdipierro <[email protected]>: > > > > > Hi Ron, > > > > I do not much about this topic. Will single master be enough? > > > > You may want to look into these tools as well. > > > > >http://www.slony.info/ > > > >http://www.sistemasagiles.com.ar/trac/wiki/PyReplicaEn > > > >https://public.commandprompt.com/projects/replicator > > > > > On Nov 11, 1:51 pm, ron_m <[email protected]> wrote: > > > >> Any of you have experience with Bucardo or pgpool-II as a replication > > > >> add-on? > > > > >> Some background: > > > >> I switched from MySQL to PostgreSQL very cleanly using web2py as the > > > >> vehicle. Sort description to document the process: Made a copy of the > > > >> app, removed the content of the databases directory, added the > > > >> prerequisite components (database and driver) to the system, created > > > >> an empty DB, changed the connection string in the model, started MySQL > > > >> verison of app in shell mode and ran all the data out to one CSV file > > > >> and finally started the PostgreSQL version up in shell mode and did an > > > >> import of the same CSV file followed by a db.commit(). After all that > > > >> the application worked except for one group by orderby query > > > >> PostgreSQL didn't like which was easy to fix and the change worked in > > > >> MySQL as well. This was a database with 28 tables linked with lots of > > > >> relations. > > > > >> My compliments to this great application server and infrastructure > > > >> surrounding it. Of the available migration tools I found out on the > > > >> net, most failed to work and would require extensive manual editing. > > > > >> The application will be installed in 10 locations scattered all over > > > >> Alaska. All the locations are connected by a WAN with IPSEC to form a > > > >> VPN so it looks like it is all in the same room except for network > > > >> performance. > > > > >> Each location must survive a network outage and continue to work, The > > > >> weather can be a problem up there. > > > > >> Any data tables that change rapidly are to remain local to each > > > >> location. > > > > >> About 2/3 of the database is configuration information which changes > > > >> very slowly. One table if this were running would have changed once in > > > >> 5 years. Some tables change more often as employees come and go or > > > >> equipment is added to a location. Config changes can be delayed by > > > >> downed connections so eventual consistency is okay. > > > > >> I need something automatic since the people using the system are not > > > >> technical and cannot be depended on to to a task. > > > > >> By restricting the application I could get the updates to one database > > > >> instance but then there is a time delay until the local copy is in > > > >> sync. > > > > >> I looked at MySQL Replication as described in the Linux Journal > > > >> article July 2010 where they do a ring which has each server to the > > > >> left in the ring is master to the slave to the right but I could see > > > >> with intermittent networks down due to bad weather this could be a > > > >> headache waiting to happen. Also the MySQL licensing has a degree of > > > >> uncertainty to it so I would rather stay away. > > > > >> I am aware of PostgreSQL-R which is in beta, The uuid and timestamps > > > >> available in web2py model help but then needs to be driven by cron in > > > >> a batch oriented update. > > > > >> Sometimes I look at the NoSQL databases like CouchDB or MongoDB but > > > >> then the foreign keys from the rapidly changing data is a problem. I > > > >> could bridge it using equipment hostname or something like that but > > > >> still I would rather stay inside one database. > > > > >> Hard problem to solve completely I think. > > > > >> Comments? > > > > >> Thanks > > > > >> Ron > >
