I'm not familiar with PostgreSQL's replication capabilities, but I'd be concerned about primary key duplication and possible data loss (this would be outside of Cayenne's control). For example, what would happen if both applications ran the sequence to generate PKs at the same time?
-----Original Message----- From: Borut Bolcina [mailto:[EMAIL PROTECTED] Sent: Monday, July 31, 2006 11:52 AM To: cayenne-user Subject: Database replication and caching Hello, I need an advice on using Cayenne in an environment where two PostgeSQL databases are configured to replicate from each other for failover capability. I am thinking of two Cayenne enabled applications (load distribution) which insert records in one of those two databases. Application one (A1) inserts in database one (DB1) and application two (A2) inserts in database two (DB2). The insertion, deletion or update will cause Java triggers in PostgreSQL to call appropriate Java method in the application. If for any reason one of the databases is down for some time, the replication mechanism will bring the second database up-to date which will trigger invocations of the Java methods, so the second application will be in the correct state also. As long as triggers do not modify records, everything should be ok with Cayenne. In case, which I don't foresee now, the records will be modified on database level, all DataContexts should be invalidated, am I right? Is there any other (caching) problem you see in this architecture? Regards, Borut
