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https://issues.apache.org/jira/browse/HADOOP-2654?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Stu Hood updated HADOOP-2654:
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Status: Open (was: Patch Available)
Also, I just noticed that this patch does not fully resolve the issue. The
Filter.and(Filter) and Filter.or(Filter) perform AND and OR on the bytes
respectively, which can result in negative values in the resulting
CountingBloomFilter.
I think I'll write a patch to replace the byte storage with 4bit so that we can
use the full range of the buckets.
> CountingBloomFilter can overflow its storage
> --------------------------------------------
>
> Key: HADOOP-2654
> URL: https://issues.apache.org/jira/browse/HADOOP-2654
> Project: Hadoop
> Issue Type: Bug
> Components: contrib/hbase
> Reporter: Stu Hood
> Attachments: counting-overflow.patch
>
>
> The org.onelab.filter.CountingBloomFilter implementation does not check the
> value of a bucket before incrementing/decrementing it. The buckets in a
> Counting Bloom filter must not be allowed to overflow, and if they reach
> their maximum value, they must not be allowed to decrement. This is the only
> way to preserve the assumptions of the filter (without larger buckets). See:
> http://en.wikipedia.org/wiki/Bloom_filter#Counting_filters
> Currently, if enough values hash to a bucket, the CountingBloomFilter may
> begin reporting false negatives when it wraps back around to 0.
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