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https://issues.apache.org/jira/browse/SOLR-1375?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12745800#action_12745800
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Jason Rutherglen commented on SOLR-1375:
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Lance,
Thanks for the info. BloomFilters can be ORed together. Hadoop
uses BFs for map side joins, which is similar to this use case.
Centralizing will help when performing millions of id membership
tests, though I'm going to benchmark first and see if the
current patch is good enough.
-J
> BloomFilter on a field
> ----------------------
>
> Key: SOLR-1375
> URL: https://issues.apache.org/jira/browse/SOLR-1375
> Project: Solr
> Issue Type: New Feature
> Components: update
> Affects Versions: 1.4
> Reporter: Jason Rutherglen
> Priority: Minor
> Fix For: 1.5
>
> Attachments: SOLR-1375.patch
>
> Original Estimate: 120h
> Remaining Estimate: 120h
>
> * A bloom filter is a read only probabilistic set. Its useful
> for verifying a key exists in a set, though it returns false
> positives. http://en.wikipedia.org/wiki/Bloom_filter
> * The use case is indexing in Hadoop and checking for duplicates
> against a Solr cluster (which when using term dictionary or a
> query) is too slow and exceeds the time consumed for indexing.
> When a match is found, the host, segment, and term are returned.
> If the same term is found on multiple servers, multiple results
> are returned by the distributed process. (We'll need to add in
> the core name I just realized).
> * When new segments are created, and commit is called, a new
> bloom filter is generated from a given field (default:id) by
> iterating over the term dictionary values. There's a bloom
> filter file per segment, which is managed on each Solr shard.
> When segments are merged away, their corresponding .blm files is
> also removed. In a future version we'll have a central server
> for the bloom filters so we're not abusing the thread pool of
> the Solr proxy and the networking of the Solr cluster (this will
> be done sooner than later after testing this version). I held
> off because the central server requires syncing the Solr
> servers' files (which is like reverse replication).
> * The patch uses the BloomFilter from Hadoop 0.20. I want to jar
> up only the necessary classes so we don't have a giant Hadoop
> jar in lib.
> http://hadoop.apache.org/common/docs/current/api/org/apache/hadoop/util/bloom/BloomFilter.html
> * Distributed code is added and seems to work, I extended
> TestDistributedSearch to test over multiple HTTP servers. I
> chose this approach rather than the manual method used by (for
> example) TermVectorComponent.testDistributed because I'm new to
> Solr's distributed search and wanted to learn how it works (the
> stages are confusing). Using this method, I didn't need to setup
> multiple tomcat servers and manually execute tests.
> * We need more of the bloom filter options passable via
> solrconfig
> * I'll add more test cases
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