ibatis-user-java mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Mike Fagan <mfa...@tde.com>
Subject Re: N+1 with a twist?
Date Fri, 11 Feb 2005 21:14:07 GMT
Nathan, are you using oracle version 4?
If you are using a newer version then the limit on outer joins is about 256.


Nathan Maves wrote:

> This was all looking great but I hit a show stopper.
>
> I have one parent table with 3 child tables.  The problem is that the 
> child rows might or might not be there.  This means that I have to use 
> an outer join to these tables.  Oracle only allows a table to have one 
> outer join.  Suck!
>
> Nathan
>
> On Feb 11, 2005, at 1:37 PM, Clinton Begin wrote:
>
>> Doesn't matter.  In series, or in parallel, any number of levels, any
>> time any place.  It will work.
>>
>> Each resultMap="" mapping is treated separately.
>>
>> The coolest thing is that to do all of this it still only iterates
>> over the result set a single time...  ;-)
>>
>> Cheers,
>> Clinton
>>
>>
>> On Fri, 11 Feb 2005 12:50:05 -0700, Nathan Maves 
>> <Nathan.Maves@sun.com> wrote:
>>
>>> How about 3 levels deep?
>>>
>>> A from request
>>>         List of B from products
>>>         List of C from approvals
>>>                 User object from users (where user's id maps to a 
>>> column in the
>>> approvals table)
>>>
>>>
>>> Nathan
>>>
>>> On Feb 9, 2005, at 10:30 AM, Clinton Begin wrote:
>>>
>>>> If you can join the data into a single resultset with repeating
>>>> groups, the N+1 solution will work, no matter how the collections are
>>>> arranged.
>>>>
>>>> As long as you group by some column in table_a, you can separately map
>>>> 2 collections on the same class.
>>>>
>>>> This will work.
>>>>
>>>> Try it out!
>>>>
>>>> Clinton
>>>>
>>>> On Wed, 09 Feb 2005 10:21:54 -0700, Nathan Maves
>>>> <Nathan.Maves@sun.com> wrote:
>>>>
>>>>> I dont think that the current implementation will work for this but I
>>>>> was looking for some best practices on how to do it.
>>>>>
>>>>> Parent Class A has n number of List properties that all come for 
>>>>> their
>>>>> own tables.
>>>>>
>>>>> A from table_a
>>>>>         List of B from table_b
>>>>>         List of C from table_c
>>>>>         .
>>>>>         .
>>>>>         .
>>>>>
>>>>>
>>>>> Nathan
>>>>>
>>>>>
>>>
>>>
>
>



Mime
View raw message