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From "Anupam Singh" <avsi...@gmail.com>
Subject Re: Bloom Filter analogy in SQL
Date Mon, 15 Apr 2013 19:43:34 GMT
Many join implementations use bloom filters built on the smaller to eliminate rows on the larger
tables in SQL queries. Many industrial RDBMS engines will show the use of bloom filters in
SQL explain plans.


For instance, oracle explain plans call these joins bloom filters as SYS_OP_BLOOM_FILTER :-


https://forums.oracle.com/forums/thread.jspa?threadID=2470938


It could be useful for performance tuning. Hope this helps.


-Anupam

—
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On Fri, Mar 29, 2013 at 11:32 PM, Ted Dunning <tdunning@maprtech.com>
wrote:

> This isn't a very Hadoop question.
> A Bloom filter is a very low level data structure that doesn't really any
> correlate in SQL.  It allows you to find duplicates quickly and
> probabilistically.  In return for a small probability of a false positive,
> it uses less memory.
> On Fri, Mar 29, 2013 at 5:36 PM, Sai Sai <saigraph@yahoo.in> wrote:
>> Can some one give a simple analogy of Bloom Filter in SQL.
>> I am trying to understand and always get confused.
>> Thanks
>>
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