Re: Delete cascade?
Re: Delete cascade?
- Subject: Re: Delete cascade?
- From: Chuck Hill <email@hidden>
- Date: Mon, 19 Mar 2007 08:57:12 -0700
On Mar 18, 2007, at 10:11 PM, Ian Joyner wrote:
Hi Peter,
What you say makes sense. Maybe, because my dependent entity does
not have any further cascades, I'm not seeing anything else being
brought into memory (maybe it's already there).
I think what I would expect is to see is:
SELECT * FROM <owned_table> WHERE OWNER_KEY = <PRIMARY_KEY of owner>
<processing of any cascades from those records>
DELETE FROM <owned_table> WHERE OWNER_KEY = <PRIMARY_KEY of owner>
That is not safe. What if records were added to <owned_table> with
an OWNER_KEY = <PRIMARY_KEY of owner> while you were processing the
cascades? I suspect that is why the designers of EOF elected to not
use this "optimization". Generally, they seem to have chosen safe
over fast in implementing EOF.
Chuck
However, all I see is the DELETEs a single one at a time. Maybe I
just have an simple case?
Thanks
Ian
On 19/03/2007, at 2:08 PM, Peter Vandoros wrote:
Hi Ian,
WebObjects does this because it needs to bring all the EO's into
memory to process the delete rules specified in your EOModel.
Regards
Peter
Ian Joyner wrote:
I just noticed in my system that if I have the cascade delete
rule set on a to-many relationship in EOModeler that the deletes
happen one by one.
That is if I have a master record with three detail records, WO
issues three SQL DELETEs.
The setup is, each record has a primary key PRIMARY_KEY, which
relates to the owned records which have OWNER_KEY. To do the
delete cascade, I would think that DELETE FROM <owned table>
WHERE OWNER_KEY = <PRIMARY_KEY of owner> would suffice.
Have I got something set up wrong here, or am I missing something?
Thanks
Ian Joyner
Sportstec
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