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From Clinton Begin <clinton.be...@gmail.com>
Subject Re: n+1 is triggering multiple queries, 3?
Date Tue, 12 Jul 2005 14:08:50 GMT
Kris,

This is the right list (user-java@ibatis.com).

Sorry nobody responded. I had a quick look when you originally sent it, and 
I couldn't see how it was possible that the groupBy or a nested resultMap 
could cause additional queries...

Perhaps someone else has thoughts? If not, you might have to write an 
isolated unit test and submit it through JIRA.

Cheers,
Clinton


On 7/9/05, Kris Rasmussen <kristapestry@yahoo.com> wrote:
> 
> I have an n+1 mapping. When I look at mysql health in the administrator it 
> apears that 3 queries are being executed instead of one. The first query 
> gets executed when I retrieve the intial object via queryForObject. The next 
> two queries are being executed when I attempt to access the List which 
> stores the related objects from the main object. I am very curious what is 
> going on since I don't know how Ibatis could even know what query to execute 
> to get the items later?
>  The following maps are used to retrive a single instance of classB with 
> all of its classA children stored in one of its properties which is of 
> course a list.
>   
> <resultMap id="getClassAResult" class="classA">
> 
> ... some basic properties
> 
> </resultMap>
> 
> <resultMap id="getClassBResult" class="classB">
> 
> <result property="primKey1" column="classB.primKey1"/>
> 
> <result property="primKey2" column="classB.primKey2"/>
> 
> ... some more properties
> 
> </resultMap>
> 
> <resultMap id="getClassBWithClassAsResult" class="classB" 
> extends="getClassBResult" groupBy="primKey1,primKey2">
> 
> <result property="classAs" resultMap="namespace.getClassAResult"/>
> 
> </resultMap>
> 
>  and my select statement...
> 
> <select id="getClassBWithClassAs" parameterClass="keyClass" 
> resultMap="getClassBWithClassAsResult">
> 
> SELECT classB.*,classA.* FROM classB ,classA
> 
> WHERE classB.primKey1=#primKey1# AND classB.primKey2=#primKey2# AND 
> gallery_image.SiteId=#siteId# AND gallery_image.BlockId=#blockId#
> 
> GROUP BY classB.primKey1,classB.primKey2,classA.primKey3
> 
> </select>
> 
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