Thanks for the help. I am definitely going to do my next project in
Cayenne.
-John
On 9/22/04 11:26 AM, "Gentry, Michael" <michael_gentr..anniemae.com> wrote:
> If you look in the DataNode of your model, you'll see a "Min
> Connections" field and a "Max Connections" field. If both are 1,
> Cayenne will only use 1. Adjust as you need.
>
> Cayenne can do optimistic locking (at least with 1.1, I don't remember
> about 1.0). In the DataMap section of your model, look at the ObjEntity
> configuration. Make sure you check "Optimistic Locking" under the
> "Entity" tab. Then under the "Attributes" tab there is a "Used for
> Locking" column with checkboxes for each attribute. You should check
> all of these fields in general, with the possible exception of BLOBs
> (you'll obviously need to decide what's important for your case). You
> can also select relationships to be optimistically locked, too.
>
> When you modify an existing record and save it back to the database,
> Cayenne will generate SQL something like this:
>
> UPDATE FooBar
> SET x = '123'
> WHERE x = 'foo' AND y = 'bar' AND z = 'baz' AND primaryKey = 547124
>
> In this example, your FooBar entity contained an "x", "y", and "z"
> column and you had them all checked under the "Use for Locking" column.
> Cayenne remembers the previous values of all the columns that are used
> for locking and includes those original values as part of the UPDATE
> statement. Of course, if one of the values got changed (like, you did a
> manual database fix), then the UPDATE will fail and your application can
> catch the error.
>
> /dev/mrg
>
>
> -----Original Message-----
> From: John Martyniak [mailto:jmarty..x.netcom.com]
> Sent: Wednesday, September 22, 2004 10:47 AM
> To: Cayenne User
> Subject: Kind of a simple question
>
>
> Hi,
>
> How many connections to the DB does Cayenne use, when used with
> Servlets?
> Does it maintain a single connection, or does it maintain a pool of
> connections?
>
> Also does Cayenne have any sort of Object Locking mechanism? Or does
> that
> need to be custom developed? Because I will have customers creating and
> updating records.
>
> The reason that I ask is that I currently use another ORM, that uses one
> (I
> think that it is two actually) connection to the DB when used in a
> Servlet
> container.
>
> I am getting ready to start a new project and would like to try it with
> Cayenne, but I have some concerns.
>
> Thanks in advance for the information.
>
> -John
>
>
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