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From Apache Wiki <wikidi...@apache.org>
Subject [Hadoop Wiki] Update of "Hbase/UsingBloomFilters" by Misty
Date Thu, 22 Oct 2015 21:07:49 GMT
Dear Wiki user,

You have subscribed to a wiki page or wiki category on "Hadoop Wiki" for change notification.

The "Hbase/UsingBloomFilters" page has been changed by Misty:
https://wiki.apache.org/hadoop/Hbase/UsingBloomFilters?action=diff&rev1=8&rev2=9

- == Current ==
+ The HBase Wiki is in the process of being decommissioned. The info that used to be on this
page has moved to http://hbase.apache.org/book.html#schema.bloom. Please update your bookmarks.
  
- Bloom filters didn't work reliably in 0.19.x and are a noop in 0.20.x.  They should make
a re-appearance in 0.21.x HBase.
- 
- == Historically ==
- 
- Bloom filters can be enabled on a per-column family basis in HBase. By specifying true for
the bloom filter parameter in the constructor for H!ColumnDescriptor or by calling H!ColumnDescriptor.setBloomFilter(true),
a [[http://portal.acm.org/citation.cfm?id=362692&dl=ACM&coll=portal|bloom filter]]
as defined by Bloom in 1970 will be added to the column family.
- 
- This can be done either at table creation time or by disabling the table and modifying the
column through the H!BaseAdmin.modifyColumn API.
- 
- Bloom filters are created using the mechanism specified by [[http://www.eecs.harvard.edu/~michaelm/NEWWORK/postscripts/BloomFilterSurvey.pdf|Broder
and Mitzenmacher]] which computes the vector size using 4 hash functions.
- 
- Junit testing for bloom filters can be found in hbase.regionserver.!TestBloomFilters.
- 

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