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From Michael Gentry <blackn...@gmail.com>
Subject Re: Caching Relationship Objects/Queries - Cayenne 3.1
Date Tue, 17 May 2016 18:48:21 GMT
Hi Frank,

There might still be something more going on here.

When you initially fetch object2 for the first time, the relationship to
object1 is a "fault" (assuming you don't prefetch).  When you say
object2.getObject1(), Cayenne will trigger the fault resulting in a SELECT
statement sent to the DB, which gets populated into object1, which replaces
the fault.  The next time you say object2.getObject1(), it should return
object1 since the fault is no longer there.  I glossed over a few things
there, but I hope you understood my gist.  I'm assuming something has
happened to your object2 between the first and second calls to getObject1()
which is causing the fault to be re-established and therefore re-tripped.

mrg



On Tue, May 17, 2016 at 2:29 PM, Frank Herrmann <
frank.herrmann@modernizingmedicine.com> wrote:

> I believe your first example. Here is some clarification.
>
> object2 = // something that fetches object2 -- object2 is now in the object
> cache
> object1 = object2.getObject1(); // makes a call to the database and fetches
> object1 -- does not put object1 in the object cache
> object1 = object2.getObject1(); // makes another call to the database to
> fetch object1, since object1 is not in the object cache
>
> -Frank
>
> On Tue, May 17, 2016 at 2:21 PM, Michael Gentry <blacknext@gmail.com>
> wrote:
>
> > Hi Frank,
> >
> > I'm a little confused by this part:
> >
> > "If we retrieve Object2 from the database, it is placed in the object
> > cache. Afterwards, if we retrieve Object1 via the getter in Object2,
> > Object1 is not cached. So, every time we make the request for Object1 via
> > the getter, another call is made to the database."
> >
> > Are you saying:
> >
> > object2 = // something that fetches object2
> > object1 = object2.getObject1(); // trips fault, fetches object1
> > object1 = object2.getObject1(); // trips fault, fetches object1
> >
> > Or:
> >
> > object2 = // something that fetches object2
> > object1 = object2.getObject1(); // trips fault, fetches object1
> > object2 = // refetch object2 from cache
> > object1 = object2.getObject1(); // trips fault, fetches object1
> >
> > Thanks,
> >
> > mrg
> >
> >
> > On Tue, May 17, 2016 at 9:32 AM, Frank Herrmann <
> > frank.herrmann@modernizingmedicine.com> wrote:
> >
> > > Hello all,
> > >
> > > I have a question regarding how Cayenne does caching. Right now, if we
> > > retrieve an object from the database via Cayenne, it is placed in the
> > > object cache. However, in our experience, if we then retrieve another
> > > object via the relationship on the first object, it is not cached.
> > >
> > > A rough example:
> > >
> > > public class Object1 {
> > >     ... misc attributes ...
> > > }
> > >
> > > public class Object2 {
> > >     ... misc attributes...
> > >     private Object1 object1;
> > >
> > >     public Object1 getObject1() {
> > >         return object1;
> > >     }
> > > }
> > >
> > > If we retrieve Object2 from the database, it is placed in the object
> > cache.
> > > Afterwards, if we retrieve Object1 via the getter in Object2, Object1
> is
> > > not cached. So, every time we make the request for Object1 via the
> > getter,
> > > another call is made to the database. I have fixed this for individual
> > > instances by using prefetches. However, our application is quite large,
> > and
> > > I don't like the idea of tracking down case.
> > >
> > > Is there some way for Cayenne to place the relationship objects into
> the
> > > object cache the first time they are retrieved? We are using EhCache
> for
> > > our query caching, so if the object cache is not an options, is there a
> > way
> > > to store these relationships in a short lived query cache?
> > >
> > > Thanks for the help.
> > >
> > > -Frank
> > >
> > > --
> > > FRANK HERRMANN
> > > SOFTWARE ENGINEER
> > >
> > > T: 561-880-2998 x1563
> > >
> > > E: frank.herrmann@modmed.com
> > >
> > >
> > >
> > > [image: [ Modernizing Medicine ]] <http://www.modmed.com/>
> > > [image: [ Facebook ]] <http://www.facebook.com/modernizingmedicine>
> > > [image:
> > > [ LinkedIn ]] <http://www.linkedin.com/company/modernizing-medicine/>
> > > [image:
> > > [ YouTube ]] <http://www.youtube.com/user/modernizingmedicine>
> [image: [
> > > Twitter ]] <https://twitter.com/modmed_EMA> [image: [ Blog ]]
> > > <http://www.modmed.com/BlogBeyondEMR> [image: [ Instagram ]]
> > > <http://instagram.com/modernizing_medicine>
> > >
> >
>
>
>
> --
> FRANK HERRMANN
> SOFTWARE ENGINEER
>
> T: 561-880-2998 x1563
>
> E: frank.herrmann@modmed.com
>
>
>
> [image: [ Modernizing Medicine ]] <http://www.modmed.com/>
> [image: [ Facebook ]] <http://www.facebook.com/modernizingmedicine>
> [image:
> [ LinkedIn ]] <http://www.linkedin.com/company/modernizing-medicine/>
> [image:
> [ YouTube ]] <http://www.youtube.com/user/modernizingmedicine> [image: [
> Twitter ]] <https://twitter.com/modmed_EMA> [image: [ Blog ]]
> <http://www.modmed.com/BlogBeyondEMR> [image: [ Instagram ]]
> <http://instagram.com/modernizing_medicine>
>

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