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From Dan Armbrust <daniel.armbrust.l...@gmail.com>
Subject Re: OutOfMemory and IOException Access Denied errors
Date Mon, 22 May 2006 13:48:05 GMT
>> Your out of memory error is likely due to a mysql bug outlined here:
>>
>>   http://bugs.mysql.com/bug.php?id=7698
> Thanks for the article. My query executed in no time without any errors !!!


The MySQL drivers are horrible at dealing with large result sets - that 
article gives you the workaround to tell it to bring the results back as 
they are needed (like it should in the first place) but I have found 
that it isn't reliable - it tends to drop out at random points during 
the query - so you will get a different number of rows each time you 
rerun the query.  In MySQL - the only reliable way I have found to get 
all of the results from a large table is to use their "limit" keyword in 
the query, and only ask it for X (I usually use 10,000, but use whatever 
works best with your system) number of rows as a time, and then keep 
rerunning the query, incrementing up the start position of the "limit" 
keyword.  This issue also varies a lot from version to version of the 
driver - some versions have been completely broken, and others are only 
slightly broken.  To bad we can't get lucene quality code everywhere :)



 >> Exception in thread "main" java.io.IOException: Access is denied

To me, that really seems like you have an issue with the location that 
you are writing the index to.  I would make sure you have full write 
permissions to the location, and make sure there aren't some old / 
invalid files sitting in there.

Dan


-- 
****************************
Daniel Armbrust
Biomedical Informatics
Mayo Clinic Rochester
daniel.armbrust(at)mayo.edu
http://informatics.mayo.edu/

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