Thanks for the suggestion, Aleksey. I'm not very good at writing English, so if someone come up with addition to the doc, I will appreciate. -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese: http://www.sraoss.co.jp
> Dear Tatsuo, > > Thanks, that's a great explanation, very clear. > > Maybe you could add it to the pgpool-II manual, in the > Replication section? Just a suggestion. > > Thank you! > Aleksey > > > On Mon, Jun 7, 2010 at 6:00 PM, Tatsuo Ishii <[email protected]> wrote: > >> Hi. We want to have redundancy for our database; > >> is pgpool-II the right tool, with it's replication mode? > >> > >> We want to have 2 database servers, and if one > >> dies, our application just goes on using the other > >> one, while we repair the broken one. > >> > >> Can pgpool-II replicate writes such that if a write > >> query is submitted, pgpool-II will write it to DB server > >> A and DB server B, and will only return a success > >> to the client if both writes succeeded? otherwise > >> it will return a failure, perform any necessary rollback > >> if the write was replicated only to one server? > > > > Yes, pgpool-II exactly works as you described. Plus, with write query > > pgpool-II start a transaction if it's not already started by user. > > The write order is first A then B (if A is the first one on > > pgpool.conf). Commit order is B then A. > > > > If write query fails, pgpool-II aborts the transaction and start > > a degenration, which will be seen as connection shutdown from > > PostgreSQL server by client. By reconnecting pgpool-II, client can use > > the healthy PostgreSQL. > > > > Please note that "fail" does not mean here a query error (for example, > > violation of constraints). Rather "fail" means network error or > > PostgreSQL server down or some such. > > > >> If that's not how pgpool-II replication works, how does > >> it work? I've looked at the manual but I still don't > >> understand. > >> > >> I'm familiar with replication with Postgres 8 log shipping > >> (warm standby), Postgres 9 streaming replication > >> (hot standby), and Slony (hot standby). How does > >> Pgpool-II replication work and how does it compare to > >> the Postgres/Slony replication? > > > > They are all log(physical or logical one) based asynchronous > > replication systems. Pgpool-II is a query based synchronous > > replication. That's the big difference. In addition, those > > replication systems do not have any automatic failover/load balancing > > functionality while pgpool-II has. > > -- > > Tatsuo Ishii > > SRA OSS, Inc. Japan > > English: http://www.sraoss.co.jp/index_en.php > > Japanese: http://www.sraoss.co.jp > > > _______________________________________________ > Pgpool-general mailing list > [email protected] > http://pgfoundry.org/mailman/listinfo/pgpool-general _______________________________________________ Pgpool-general mailing list [email protected] http://pgfoundry.org/mailman/listinfo/pgpool-general
