On Thu, Feb 13, 2014 at 02:09:30PM -0800, tiger peng wrote: > Hello All, > I am trying to using bucardo (b5) to replicate tables from multiple > database on multiple hosts. So I plan to install bucardo on Slave host. > My questions are: > if there is network glitch, while the replication catch up later when > the connection is restored? If so where the change buffered? Is there > performance impact on masters?
The short answer is "yes, bucardo will (try to) catch up later". When a sync is created, bucardo creates a new schema in each master database, containing several tables. When a change occurs in a database, it gets recorded in those tables. If Bucardo can't, or doesn't, replicate the change immediately for whatever reason, the change sits in those tables until conditions allow it to be replicated. If there get to be lots of changes buffered, it can take a lot of work for bucardo to catch up, and sometimes it's effectively impossible, such as when transaction serialization or other locking problems get in the way. Just how much downtime you can support without that sort of problem depends very much on your setup and what other stuff is using your database. It's a good idea to monitor bucardo to make sure it's replicating properly, because otherwise you might go for months buffering these changes, and not know about it. You might use check_postgres to do that (http://bucardo.org/wiki/Check_postgres), or some other tool of your choice. -- Josh Tolley [email protected] 801-987-0252 End Point Corporation http://www.endpoint.com
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