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From Borut BolĨina <>
Subject Database replication and caching
Date Mon, 31 Jul 2006 15:52:21 GMT

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 

Is there any other (caching) problem you see in this architecture?


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