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https://issues.apache.org/jira/browse/SPARK-18252?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15650676#comment-15650676
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Aleksey Ponkin commented on SPARK-18252:
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[~cloud_fan] Can you, please clear for me some things:
[BloomFilterImpl.java |
https://github.com/apache/spark/blob/39e2bad6a866d27c3ca594d15e574a1da3ee84cc/common/sketch/src/main/java/org/apache/spark/util/sketch/BloomFilterImpl.java#L93-L98]
here you are using int combinedHash , but we can create BloomFilter with
expected insertions that are much larger than Integer.MAX_VALUE. It turns out
for me, that for such filters all changed bits inside BitArray will be in a
range [0.. Integer.MAX_VALUE]. That means that we can not guarantee expected
false positive probability for filters larger than Integer.MAX_VALUE. Is it
correct? Or may be it is a bug? I`ve just checked guava library BloomFilter,
and they use different strategies to translate element instances, to bit
indexes [BloomFilterStrategies |
https://github.com/google/guava/blob/6ded67ff124f1be4f318dbbeae136d0c995faf37/guava/src/com/google/common/hash/BloomFilterStrategies.java].
If it is a bug, do we need another lira for that? Or I can fix it along with
this lira ticket?
Thanks in advance!
> Improve serialized BloomFilter size
> -----------------------------------
>
> Key: SPARK-18252
> URL: https://issues.apache.org/jira/browse/SPARK-18252
> Project: Spark
> Issue Type: Improvement
> Components: Spark Core
> Affects Versions: 2.0.1
> Reporter: Aleksey Ponkin
> Priority: Minor
>
> Since version 2.0 Spark has BloomFilter implementation -
> org.apache.spark.util.sketch.BloomFilterImpl. I have noticed that current
> implementation is using custom class org.apache.spark.util.sketch.BitArray
> for bit vector, which is allocating memory for the whole filter no matter how
> many elements are set. Since BloomFilter can be serialized and sent over
> network in distribution stage may be we need to use some kind of compressed
> bloom filters? For example
> [https://github.com/RoaringBitmap/RoaringBitmap][RoaringBitmap] or
> [javaewah][https://github.com/lemire/javaewah].
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