Re: strange EO inheritance issue
Re: strange EO inheritance issue
- Subject: Re: strange EO inheritance issue
- From: Patrick Robinson <email@hidden>
- Date: Thu, 03 Aug 2006 22:32:07 -0400
Ken,
I'm having a little trouble figuring out what the performance
problems might be. Wouldn't it depend on the access patterns? In
this app, each A object belongs to a different user, and they create
shared C objects, which are associated with the A's via B. Just
because one type of C corresponds to an association via a type of B
which happens to be stored in a separate B table... I dunno, it
doesn't seem like a problem to me. What am I not considering?
But.... that said, I think your suggestion of putting the extra
columns in a separate table with a relationship to it from the 8th
subclass is an excellent one. I should've thought of that!
Thanks,
- Patrick
On Aug 3, 2006, at 5:15 PM, Ken Anderson wrote:
Patrick,
Not to rain on your parade, but this is probably going to be a
performance nightmare (even if you get it to work right).
I would suggest putting those extra columns in a separate table,
putting a relationship to it in the 8th subclass, and setting a
nice batch fault number on it. I bet you it will perform WAY better.
Ken
On Aug 3, 2006, at 5:05 PM, Patrick Robinson wrote:
I've got a rather strange EO inheritance question. I've got a
situation where I've set up single-table inheritance (with a
subclass "type" column) for 7 out of 8 of my subclasses; and a
separate table (with the same "type" column) that has a bunch more
columns for the 8th, just because I didn't want all those columns
sitting there empty for most of the rows (i.e. for the other 7
subclasses). Probably false economy, but be that as it may....
My structure looks like this:
A <-->> B <<--> C
C is modeled as an inheritance hierarchy using horizontal mapping,
and B is modeled as the inheritance hierarchy described above,
using mostly single-table mapping. There is a different subclass
of B for each corresponding subclass of C.
It all built just fine, but when it came time to save an object of
my new C subclass (the one that corresponds to the B subclass with
its own table), the primary key of the C subclass object did not
propagate to the B subclass object -- it was left as null. This
is done with Oracle, so there's an Oracle sequence C_SEQ that's
used to obtain C's primary key, and C_ID is the primary key of all
C subclasses. Normally, this propagates to the B subclass objects
just fine (with all the other B subclasses, that is), but it isn't
working with the B subclass that is set in EOModeler to use its
own table.
Has anyone else tried to do this kind of thing, or am I just
trying to do something idiotic? :-)
--
Patrick Robinson
AHNR Info Technology, Virginia Tech
email@hidden
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