...and that's sometimes a good thing.
We use SA here with two databases (MSSQL + Sqlite) using exactly the
type of single session + multiple-bound-metadata scheme that Mike
describes above. Works fine (just don't try to join across
databases...)
On 1/28/07, Michael Bayer <[EMAIL PROTECTED]> wrote:
>
>
>
> On Jan 23, 10:36 am, "Max Ischenko" <[EMAIL PROTECTED]> wrote:
> > As far as I understand, I need a session per database. In Pylons, I get
> > it "for free" via session_context binding. In other words, I have setup
> > a session_context object for each of the database I need to work with.
>
> youd need a separate engine for each database. since different
> connection strings and all that. A single Session can in fact talk to
> multiple databases at once, so im not sure if multiple sessions/
> sessioncontexts are really required (however, i can see how it may be
> the most intuitive approach to just use separate sessions).
>
> >
> > Do I need to use separate DynamicMetaData() for each db conn? Do I need
> > to connect single metadata to the correct session? SA docs shows how to
> > connect metadata to a engine but all I have is a session.
> >
>
> OK i think talking to multiple DB's is a little involved and there is
> currently no official "pattern" to this. it also depends on how your
> multiple DB's relate to your classes. for example, if you have
> certain classes that are stored in certain DB's, you can map quite
> easily using just regular BoundMetaData instances:
>
> metadata1 = BoundMetaData('foo://database1')
> metadata2 = BoundMetaData('foo://database2')
>
> table1 = Table('table1', metadata1, autoload=True)
> table2 = Table('table2', metadata2, autoload=True)
>
> mapper(ClassA, table1)
> mapper(ClassB, table2)
>
> ...and youre done. You can use just one Session that has ClassA and
> ClassB in it at the same time. So, we have a lot of possibilities
> here, but app configs and database configs can vary greatly so it may
> be a little bit overwhelmingly open ended.
>
>
> >
>
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