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From: Vinicius Carvalho <viniciusccarvalho@gmail.com>
Date: Sat, 30 Jan 2010 00:01:29 -0200
Message-ID: <9d2777b61001291801w66fe0b45ldd76e90bab5a28f1@mail.gmail.com>
Subject: Getting Taste to work on 10M dataset
To: mahout-user@lucene.apache.org
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Hello there! I'm trying to get Taste to work on the 10M dataset but, even
following some tips from Sean on Mahout in Action, I can't get it working
using SlopeOneRecommender and JDBC.

The machine I run the examples is a Core 2 Duo 2.8 Ghz with 4GB RAM Ubuntu
9.10 64bit JDK 1.6

The Mysql is set to use up to 512MB of table cache

The JVM is running with Xmx=2048mb


I'm using spring to make things simpler but bottom line I create a slopeone
recommender using the constructor:

DataModel:JDBCDataModel
weighting:Weighted
weighting:Weighted
diffStorage:memory

The memory storage is configured:

DataModel:JDBCDataModel
weighting:Weighted
compact:false
maxEntries:100000


Running the code I get this exception:

Caused by: java.lang.NullPointerException
    at com.mysql.jdbc.ResultSetImpl.getLong(ResultSetImpl.java:2843)
    at com.mysql.jdbc.ResultSetImpl.getLong(ResultSetImpl.java:2830)
    at
org.apache.commons.dbcp.DelegatingResultSet.getLong(DelegatingResultSet.java:190)
    at
org.apache.mahout.cf.taste.impl.model.jdbc.AbstractJDBCDataModel.getLongColumn(AbstractJDBCDataModel.java:602)
    at
org.apache.mahout.cf.taste.impl.model.jdbc.AbstractJDBCDataModel$ResultSetIDIterator.nextLong(AbstractJDBCDataModel.java:677)
    at
org.apache.mahout.cf.taste.impl.recommender.slopeone.MemoryDiffStorage.buildAverageDiffs(MemoryDiffStorage.java:221)
    at
org.apache.mahout.cf.taste.impl.recommender.slopeone.MemoryDiffStorage.<init>(MemoryDiffStorage.java:115)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    at
org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:100)
    ... 57 more

I tried to replace the MemoryDiff by a JDBCDiff. After almost 1 hour running
the code, and 100% CPU usage by my mysql process. I decided to quit, is it
supposed to take so long?

I tried to change the maxEntries to a smaller value but the NullPointer
always happens. My table is not exactly like the one used as sample on the
source code, but I do inform the correct columns and they are of the same
type.

Any ideas?


-- 
The intuitive mind is a sacred gift and the
rational mind is a faithful servant. We have
created a society that honors the servant and
has forgotten the gift.

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