RE: [OJB-developers] multiple classes mapped to single table requ est for comments

[Matthew B. <ma...@so...>]

Damn oracle.

That's about... average 50 characters per fully qualified class name,
meaning a max of 5 classes in an IN statement.

Well, the code is easy enough to change, if it becomes an issue.


-----Original Message-----
From: Jakob Braeuchi [mailto:jbr...@ho...] 
Sent: Sunday, June 09, 2002 10:40 PM
To: Matthew Baird; 'Oleg Nitz';
obj...@li...
Subject: Re: [OJB-developers] multiple classes mapped to single table
request for comments

hi matthew,

> I thought about using IN, but doesn't that have a length limit? Maybe
that's
> not important for extents (people should inherit THAT much :))

afaik IN has (or at least had in previous versions) a length limit of 254 in
Oracle.

jakob

----- Original Message -----
From: "Matthew Baird" <ma...@so...>
To: "'Oleg Nitz'" <on...@uk...>;
<obj...@li...>
Sent: Sunday, June 09, 2002 9:57 PM
Subject: RE: [OJB-developers] multiple classes mapped to single table
request for comments


> Yah I figured #2 was the better was of doing it, I'm mostly done the
> implementation now.
>
> I assume for joined tables we don't need to add the class discriminator
> since that relationship shouldn't have been able to be created in the
first
> place if the class type was wrong.
>
> I thought about using IN, but doesn't that have a length limit? Maybe
that's
> not important for extents (people should inherit THAT much :))
>
> m
>
> -----Original Message-----
> From: Oleg Nitz [mailto:on...@uk...]
> Sent: Sunday, June 09, 2002 12:43 PM
> To: obj...@li...
> Subject: Re: [OJB-developers] multiple classes mapped to single table
> request for comments
>
> On Sunday 09 June 2002 19:27, Matthew Baird wrote:
> > 2. Change the select queries for classes that have the
'ojbConcreteClass'
> > column mapped to append a where discriminator based on classtype. So a
> > query for all D in the above example would include the following WHERE
> > clause
> >
> > WHERE MultiTable.CLASS_TYPE='D' OR MultiTable.CLASS_TYPE='B'
> >
> > PROS: Most efficient. No checking necessary to see if the
> > materialized object is an instance of what was requested. Iterators
Would
> > only contain valid candidates and thus size and other methods would work
> as
> > expected.
> > CONS: Bigger change, more change to SQL generation code; where
> > clause would be slower?
> +1 for #2
>
> BTW you might use the shorter syntax
>     WHERE MultiTable.CLASS_TYPE IN ('B','D')
>
> Oleg
>
>
>
>
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