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From "K. Arnold" <akarn...@comcast.net>
Subject Re: ResultHandler - OutOfMemory Exception
Date Tue, 15 Sep 2009 16:44:47 GMT

I have not used iBATIS 2 to do a comparison.  It is very well that the
assumption given to me about how RowHandler works is false.  I am in the
process of trying to figure out a good limit size to pick utilizing an AS400
jdbc driver working on a DB2 database.    

We have decided that utilizing the select statement with the limit is the
better decision choice for us.  Now we need to figure out how to optimize
it.  

Any suggestions would be appreciated :ninja:

Just to make sure I understand your reply for any future work.  I don't
believe I am using a join mapper.  I have a POJO that maps directly to a
custom (yet extremely complicated) sql statement.  The POJO doesn't have any
collections, and is basically stand alone.  It is my understanding from your
code, that my type of POJO isn't going to utilize the join mapper method,
since the next POJO will be unique.

Clinton Begin wrote:
> 
> The difference between RowHandler and ResultHandler is only in name.  They
> did the same thing.
> I'd be interested to know if iBATIS 2.x works for you in this regard. As
> far
> as I can recall, 2.x had the same design if you invoked the join mapper...
> 
> See, as soon as you try to use a JOIN to load a complex object graph, we
> need to cache the results so that iBATIS knows to append to the parent,
> rather than instantiate a new object.
> 
> Clinton
> 
> On Tue, Sep 15, 2009 at 9:04 AM, K. Arnold <akarnold@comcast.net> wrote:
> 
>>
>> Thank you for the reply.  Is it possible to make the join mapping cache a
>> configurable attribute on the mapping file?   This is my first time using
>> Ibatis and I was confidently informed that we could walk row by row over
>> a
>> result set.  I was told to look up the RowHandler interface.  It is my
>> understanding that in Ibatis 3 that the ResultHandler has replaced the
>> RowHandler.  Was there a specific design decision made not to allow a row
>> by
>> row walk through?
>>
>> As a work around I was looking into the Plugin feature.  It looks like I
>> can
>> Intercept the resultSetsHandler method, and write my own code to process
>> it.
>> In theory I could utilize the DefaultResultSetHandler code and remove the
>> cache feature in my implementation.  However I am not sure if I have
>> access
>> to the same constructor parameters at the point of the intercept.
>>
>> There is some concern around the performance of also introducing multiple
>> call backs to the Database for each "set" of data to process.  I need to
>> balance the design choice of writing my own resultSetsHandler with the
>> number of sql calls being made to the database via an offset Select call.
>>
>> I appreciate your replies to this subject.
>>
>> Clinton Begin wrote:
>> >
>> > The nestedResultObjects is necessary for join mapping.  One way to deal
>> > with
>> > this though, is to use batches of reads as well as writes.  Use the
>> > pagination facilities and possibly even the proprietary offset/limit
>> > features of your database to grab subsets of the results.
>> > Incidentally I'm rewriting the DefaultResultSetHandler to be easier to
>> > understand.  But I don't see the need for that cache going away anytime
>> > soon...
>> >
>> > Clinton
>> >
>> > On Mon, Sep 14, 2009 at 1:47 PM, K. Arnold <akarnold@comcast.net>
>> wrote:
>> >
>> >>
>> >> I am trying to iterate over a result set of 2million records, for a
>> large
>> >> bulk load and transformation into a new ODS.  It appears that I am
>> >> getting
>> >> an OutOfMemoryException because the DefaultResultSetHandler is caching
>> >> the
>> >> object in the nestedResultObjects property.  Is there some property I
>> >> should
>> >> set or statement/ method call I should be using that will allow me to
>> >> process one line at a time and not have the nestedResultObjects store
>> >> each
>> >> object?
>> >>
>> >> My goal:
>> >> * Grab a row
>> >> * Send it to be processed
>> >> * Once processed, move on to the next row.
>> >> Note: Once a row is processed I no longer need a tie back to the
>> object.
>> >>
>> >>
>> >>
>> >> I have included the custom ResultHandler, the unit test and the
>> >> configuration file.  Please let me know if you need other information.
>> >>
>> >> package com.primetherapeutics.benplanmgr.entity.rxclaim;
>> >>
>> >> import org.apache.ibatis.executor.result.ResultContext;
>> >> import org.apache.ibatis.executor.result.ResultHandler;
>> >> import org.apache.log4j.Logger;
>> >>
>> >> /**
>> >>  * @author kjarnold
>> >>  *
>> >>  */
>> >> public class GroupEligibilityResultHandler implements ResultHandler {
>> >>        Logger logger =
>> >> Logger.getLogger(GroupEligibilityResultHandler.class);
>> >>
>> >>        int count = 0;
>> >>
>> >>        public void handleResult(ResultContext context) {
>> >>                if(context.getResultObject() != null) {
>> >>                        count++;
>> >>                        logger.debug(count);
>> >>                }
>> >>                //context.stop();
>> >>        }
>> >>
>> >>        public int getCount() {
>> >>                return count;
>> >>        }
>> >>
>> >> }
>> >>
>> >>        @Test
>> >>        public void getGroupElibibilitiesByResultHandler() {
>> >>                Map<String, String> parameterMap = new HashMap<String,
>> >> String>();
>> >>                parameterMap.put("gelThruDate", "1090101");
>> >>                parameterMap.put("addDate", "1090911");
>> >>                parameterMap.put("chgDate", "1090911");
>> >>                parameterMap.put("planDate", "1090101");
>> >>                try {
>> >>                        GroupEligibilityResultHandler handler = new
>> >> GroupEligibilityResultHandler();
>> >>
>> >>
>> >>
>> session.select("com.primetherapeutics.benplanmgr.entity.rxclaim.data.GroupEligibilityMapper.getGroupEligibilities",
>> >>                                        parameterMap, handler);
>> >>                        logger.debug(handler.getCount());
>> >>
>> >>                } finally {
>> >>                        session.close();
>> >>                }
>> >>
>> >>        }
>> >>
>> >>
>> >> Here are my mapping files:
>> >>
>> >> <?xml version="1.0" encoding="UTF-8" ?>
>> >> <!DOCTYPE configuration PUBLIC "-//ibatis.apache.org//DTD Config
>> 3.0//EN"
>> >>        "http://ibatis.apache.org/dtd/ibatis-3-config.dtd">
>> >> <configuration>
>> >> <settings>
>> >>        <setting name="multipleResultSetsEnabled" value="false"/>
>> >>        <setting name="defaultExecutorType" value="BATCH"/>
>> >> </settings>
>> >>        <mappers>
>> >>                <mapper
>> >>
>> >>
>> resource="com/primetherapeutics/benplanmgr/entity/rxclaim/data/BenefitMaxSchedule.xml"/>
>> >>                <mapper
>> >>
>> >>
>> resource="com/primetherapeutics/benplanmgr/entity/rxclaim/data/GroupEligibility.xml"/>
>> >>        </mappers>
>> >> </configuration>
>> >>
>> >>
>> >>
>> >> --
>> >> View this message in context:
>> >>
>> http://www.nabble.com/ResultHandler---OutOfMemory-Exception-tp25442025p25442025.html
>> >> Sent from the iBATIS - User - Java mailing list archive at Nabble.com.
>> >>
>> >>
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>> >>
>> >>
>> >
>> >
>>
>> --
>> View this message in context:
>> http://www.nabble.com/ResultHandler---OutOfMemory-Exception-tp25442025p25455710.html
>> Sent from the iBATIS - User - Java mailing list archive at Nabble.com.
>>
>>
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>>
>>
> 
> 

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