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From nino martinez wael <nino.martinez.w...@gmail.com>
Subject Re: Re: no cache, direct reads from db each time..
Date Fri, 11 Jun 2010 11:24:06 GMT
Thanks for the input..

regards Nino

2010/6/8 Miłosz <mtylenda@o2.pl>

> Hi Nino,
>
> Roughly speaking, the idea is that you implement some database-specific
> listener. The listener is invoked when the data you are interested in
> changes. Until the listener is invoked, you can use data from the cache.
> When the listener is invoked, you refresh the entities or execute your query
> against the database.
>
> As Pinaki has mentioned, one can imagine implementing a
> RemoteCommitProvider [1] which will invalidate OpenJPA's cache when the data
> in database changes.
>
> As for SQL Server, I remember reading about a change notification facility
> but it migth be available only for .NET.
>
> Cheers,
> Milosz
>
> [1]
> http://openjpa.apache.org/builds/2.0.0/apache-openjpa-2.0.0/docs/manual/manual.html#ref_guide_event
>
>
> > Hmm it's either mysql or microsoft sql server... However if they
> > supported that feature, how would you suggest I procedede.. Calling
> > em.flush or? Anyhow I guess I could call em.flush, instead of
> > refreshing every object retrieved from the em.
> >
> > However calling it when it's only relevant would be a lot more
> performant..
> >
> > 2010/6/7 Miłosz <mtylenda@o2.pl>:
> > > Hi Nino,
> > >
> > > If you can stick to database-specific API, check whether your database
> supports some sort of change propagation mechanism.
> > >
> > > Examples:
> > > Oracle - Data Change Notification [1]
> > > PostgreSQL - LISTEN/NOTIFY [2]
> > >
> > > Regards,
> > > Milosz
> > >
> > > [1] http://www.oracle.com/technology/obe/11gr1_db/appdev/dcn/dcn.htm
> > > [2] http://jdbc.postgresql.org/documentation/83/listennotify.html
> > >
> > >
> > >
> > >
> > >> Hi
> > >>
> > >> I have a case where I need to check the database on each query,
> > >> because there can be modifications to the data from a 3rd party non
> > >> java application. Currently I have to refresh each object, otherwise
> > >> it could be stale data however this approach are really slow and feels
> > >> very wrong..
> > >>
> > >> Any ideas on what I could do?
> > >>
> > >> regards Nino
> > >
> > >
>
>

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