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https://issues.apache.org/jira/browse/HADOOP-2654?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12565449#action_12565449
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stack commented on HADOOP-2654:
-------------------------------
Lets apply the patch. It fixes the broken counting bloom filter implementation
(though this filter type doesn't look to be directly useful in hbase going
forward).
> CountingBloomFilter can overflow its storage
> --------------------------------------------
>
> Key: HADOOP-2654
> URL: https://issues.apache.org/jira/browse/HADOOP-2654
> Project: Hadoop Core
> Issue Type: Bug
> Components: contrib/hbase
> Reporter: Stu Hood
> Attachments: counting-overflow-fourbit.patch,
> counting-overflow-fourbit.patch, 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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