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From Clinton Begin <clinton.be...@gmail.com>
Subject Re: regresssion (?) in beta 9: No automapping if some properties are explicitly mapped
Date Tue, 02 Feb 2010 21:18:38 GMT
The primary reason automapping is slower is that it does not cache the
mappings.  Doing so creates concurrency challenges and also introduced the
notorious "remapResults" configuration switch in iBATIS 2.

I figure, if you want performance, map all of your results explicitly, and
turn of auto mapping (NONE).  If you want simplicity, set it to PARTIAL.  If
you have a pain fetish, set it to FULL.

Cheers,
Clinton

On Tue, Feb 2, 2010 at 1:28 PM, Stephen Friedrich <
stephen.friedrich@fortis-it.eu> wrote:

>  Thanks for the quick response. Yes, I was looking for release notes
> somewhere close to the download link, but haven’t found any.
>
> Setting FULL did the trick.
>
>
>
> I had just started to evaluate performance anyway because first results on
> the integration server were not so great:
>
> A simple web service method (JAX-RS) that reads a thousand rows, then
> serializes that to JSON (no collections involved) takes two seconds.
>
> Now looking at some profiling results in YourKit I see that
> FastResulSetHandler.applyAutomaticMappings() alone takes up more than half
> of the total web service time:
>
>
>
> [I tried to send a screenshot here, but the mail was rejected due to
> suspected spam]
>
> 56% FastResultSetHandler.applyAutomaticMappings()
>
> 18%    MetaObject.findProperty()
>
> 16%       MetaClass.buildProperty()
>
> 13%           Reflector.findPropertyName()
>
> 10%              String.toUpperCase()
>
> …
>
>
>
> I already patched Reflector.findPropertyName() so that the calls to
> toUpperCase() are avoided, using an additional map:
>
>   public String findPropertyName(String name) {
>
>       //  return caseInsensitivePropertyMap.get(name.toUpperCase());
>
>       String propName = propertyMap.get(name);
>
>       if (propName == null) {
>
>           propName = caseInsensitivePropertyMap.get(name.toUpperCase());
>
>           if (propName != null) {
>
>               propertyMap.put(name, propName);
>
>           }
>
>       }
>
>       return propName;
>
>   }
>
> That is noticeably better - most of all on the real web server, which is a
> quite dated Sparc T2000 with horrible single-thread performance.
>
> However I feel that much better performance gains should be reachable on a
> higher abstraction level.
>
>
>
> Is there a conceptual reason why automatic mapping should be noticeably
> slower than explicit mapping?
>
> That should only make a difference for the first request, shoudn’t it?
>
>
>
> Stephen
>
>
>
> *Von:* Clinton Begin [mailto:clinton.begin@gmail.com]
> *Gesendet:* Dienstag, 2. Februar 2010 16:47
> *An:* user-java@ibatis.apache.org
> *Betreff:* Re: regresssion (?) in beta 9: No automapping if some
> properties are explicitly mapped
>
>
>
> Sorry, this was a change. See the documentation for <settings> in the user
> guide. Unfortunately I poorly advertised the change.
>
> You can now configure the setting autoMappingBehavior="NONE|PARTIAL|FULL"
>
> NONE and FULL are pretty self explanatory.  FULL is how it worked in
> previous betas.  However, the new default is PARTIAL, which means that
> automapping only happens on simple, flat queries.  If you use associations
> or collections, PARTIAL mode will not automap fields.
>
> The primary reason was that I found when doing complex joins, it was hard
> to tell where the value would end up, especially in cases where the column
> matched multiple property names in parent and child objects.  So I chose
> PARTIAL to be a happy medium between simplicity and expressiveness.  But if
> you're confident that your unit testing will deal with any uncertainty, then
> feel free to set it to FULL.  Otherwise, I suggest sticking with PARTIAL.
> There is also an obvious performance benefit to setting it to PARTIAL or
> NONE.
>
> Cheers,
> Clinton
>
> On Tue, Feb 2, 2010 at 7:26 AM, Stephen Friedrich <
> stephen.friedrich@fortis-it.eu> wrote:
>
> I wonder if this was an intentional change:
>
> My mapping config looks like this:
>
>
>
>     <resultMap id="partSetMap" type="PartSetDto">
>
>         <id property="id" column="id"/>
>
>         <collection property="parts" ofType=" PartDto">
>
>             <result column="part_id" property="id" javaType="Long"/>
>
>             <result column="serial_no" property="serialNo"
> javaType="String"/>
>
>             <result column="is_reserved" property="isReserved"
> javaType="boolean"/>
>
>         </collection>
>
>     </resultMap>
>
>
>
>     <select id="selectPage" resultMap="partSetMap">
>
>         …
>
>
>
> PartSetDto has lots of other properties than “id”.
>
> In beta 8 those were automatically filled by naming convention.
>
> In beta 9 all other fields are empty.
>
>
>
>
>

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