You are viewing a plain text version of this content. The canonical link for it is here.
Posted to user@cayenne.apache.org by John Huss <jo...@gmail.com> on 2011/09/23 22:44:12 UTC
Understanding DataNode
I'm trying to understand what DataNodes are for and how they work. I know
they correspond to a specific database (basically) and that you can link one
specific DataNode to a DataMap. So why would you want to define more than
one? Is there a way to switch at runtime? How?
Thanks,
John
Re: Understanding DataNode
Posted by Mike Kienenberger <mk...@gmail.com>.
Can't speak for every situation, but it's really hard to query and
update two databases in the same operation if the schemas aren't in
the same project :-)
On Fri, Sep 23, 2011 at 9:32 PM, John Huss <jo...@gmail.com> wrote:
> Yeah, I'm mainly interested in supporting the same schema on multiple
> databases. But just out of curiosity, when using multiple schemas, what
> advantage is there in defining them in one project instead of two?
>
> John
>
> On Fri, Sep 23, 2011 at 3:54 PM, Mike Kienenberger <mk...@gmail.com>wrote:
>
>> One obvious reason is when you are working with multiple schemas on
>> multiple databases. This is why I have had more than one data node in
>> the past.
>>
>> I think other people have switched them at runtime to support the same
>> schema on multiple databases, but I will let those folks answer to
>> that.
>>
>>
>> On Fri, Sep 23, 2011 at 4:44 PM, John Huss <jo...@gmail.com> wrote:
>> > I'm trying to understand what DataNodes are for and how they work. I
>> know
>> > they correspond to a specific database (basically) and that you can link
>> one
>> > specific DataNode to a DataMap. So why would you want to define more
>> than
>> > one? Is there a way to switch at runtime? How?
>> >
>> > Thanks,
>> > John
>> >
>>
>
Re: Understanding DataNode
Posted by John Huss <jo...@gmail.com>.
Yeah, I'm mainly interested in supporting the same schema on multiple
databases. But just out of curiosity, when using multiple schemas, what
advantage is there in defining them in one project instead of two?
John
On Fri, Sep 23, 2011 at 3:54 PM, Mike Kienenberger <mk...@gmail.com>wrote:
> One obvious reason is when you are working with multiple schemas on
> multiple databases. This is why I have had more than one data node in
> the past.
>
> I think other people have switched them at runtime to support the same
> schema on multiple databases, but I will let those folks answer to
> that.
>
>
> On Fri, Sep 23, 2011 at 4:44 PM, John Huss <jo...@gmail.com> wrote:
> > I'm trying to understand what DataNodes are for and how they work. I
> know
> > they correspond to a specific database (basically) and that you can link
> one
> > specific DataNode to a DataMap. So why would you want to define more
> than
> > one? Is there a way to switch at runtime? How?
> >
> > Thanks,
> > John
> >
>
Re: Understanding DataNode
Posted by Mike Kienenberger <mk...@gmail.com>.
One obvious reason is when you are working with multiple schemas on
multiple databases. This is why I have had more than one data node in
the past.
I think other people have switched them at runtime to support the same
schema on multiple databases, but I will let those folks answer to
that.
On Fri, Sep 23, 2011 at 4:44 PM, John Huss <jo...@gmail.com> wrote:
> I'm trying to understand what DataNodes are for and how they work. I know
> they correspond to a specific database (basically) and that you can link one
> specific DataNode to a DataMap. So why would you want to define more than
> one? Is there a way to switch at runtime? How?
>
> Thanks,
> John
>