Hello.
On Jul 31, 2006, at 17:52, Borut Bolčina wrote:
> I need an advice on using Cayenne in an environment where two
> PostgeSQL databases are configured to replicate from each other
> for failover capability.
Are you using Sequoia[1] or slony[2] or creating your own solution?
> 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?
Cayenne has its own way of syncronizing cache[3] between app
instances. You could also invalidate cache manually.
- Tore.
[1] http://sequoia.continuent.org/HomePage
[2] http://gborg.postgresql.org/project/slony1/
[3] http://cwiki.apache.org/CAYDOC/configuring-caching-behavior.html
This archive was generated by hypermail 2.0.0 : Mon Jul 31 2006 - 14:30:12 EDT